RAW image format

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RAW image format

A raw image file contains minimally processed data from the image sensor of either a digital camera

Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording digital image via an electronics .Many compact digital still cameras can record sound and moving video as well as still photographs....
, image

Image scanner

In computing, a scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass window for scanning....
or motion picture film scanner

Motion picture film scanner

A motion picture film scanner is a device used in digital filmmaking to scan original Photographic film for storage as high-resolution digital intermediate files....
. Raw files are so named because they are not yet processed and therefore are not ready to be used with a bitmap graphics editor or printed

Printing

Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
. Normally, the image is processed by a raw converter in a wide-gamut

Gamut

In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors....
internal colorspace where precise adjustments can be made before conversion to a "positive" file format such as TIFF or JPEG

JPEG

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A raw image file contains minimally processed data from the image sensor of either a digital camera

Digital camera

Image scanner

Motion picture film scanner

Printing

Gamut

JPEG

In computing, JPEG is a commonly used method of for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality....
for storage, printing, or further manipulation, which often encodes the image in a device-dependent colorspace. These images are often described as "RAW image files" based on the erroneous belief that they represent a single file format. In fact there are dozens if not hundreds of raw image formats in use by different models of digital equipment (like cameras or film scanners).

Raw image files are sometimes called digital negatives, as they fulfill the same role as negatives

Negative (photography)

In photography, a negative may refer to three different things, although they are all related....
in film photography: that is, the negative is not directly usable as an image, but has all of the information needed to create an image. Likewise, the process of converting a raw image file into a viewable format is sometimes called developing a raw image, by analogy with the film development process used to convert photographic film

Photographic film

Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and of the film....
into viewable prints. The selection of the final choice of image rendering is part of the process of white balancing and color grading

Color grading

Color grading is the process of altering and enhancing the color of a film or television image, either electronically, photo-chemically or digitally....
.

Like a photographic negative, a raw digital image may have a wider dynamic range

Dynamic range

Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity, such as in sound and light....
or color gamut than the eventual final image format, and is usually the one "closest" to the real picture in the sense that it preserves most of its details. Raw image formats' purpose is to faithfully record both 100% of exactly what the sensor "saw" or "sensed" (the data), and the conditions surrounding the recording of the image (the metadata

Metadata

Metadata is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema....
).

Rationale

Providing a detailed and concise description of the content of raw files is highly problematic. There is no single raw format; formats can be similar or radically different. Different manufacturers use their own proprietary and typically undocumented formats, which are collectively known as raw format. Often they also change the format from one camera model to the next. Several major camera manufacturers, including Nikon

Nikon

, also known as Nikon or Nikon Corp., is a multinational corporation headquartered in Tokyo, Japan specializing in optics and imaging....
, Canon and Sony

Sony

is a multinational corporation list of conglomerates corporation headquartered in Minato, Tokyo, Japan, and one of the world's largest media conglomerates with revenue exceeding US$99.1 billion ....
, encrypt

Encryption

In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key ....
portions of the file in an attempt to prevent third-party tools from accessing them.

This industry-wide situation of inconsistent formatting has concerned many photographers who worry that their valuable raw photos may someday become inaccessible, as operating systems and applications become obsolete and abandoned raw formats are dropped from new software. The availability of high-quality open source

Open source

Open source is an approach to design, development, and distribution offering practical accessibility to a product's source . Some consider open source as one of various possible design approaches, while others consider it a critical Strategy element of their business operations....
software which decodes raw image formats, particularly dcraw

Dcraw

dcraw is an open source computer program which is able to read numerous raw image formats, typically produced by high-end digital cameras. dcraw converts these images into the standard portable pixmap and Tagged Image File Format image formats....
, has helped to alleviate these concerns.

There are several would-be standards competing for digital camera industry buy-in. (See the "Standardization section, below.)

Raw image formats are intended to reproduce as closely as possible (i.e. at the best of the specific sensor's performance) the sensitometry

Sensitometry

Sensitometry is the scientific study of light-sensitive materials, especially photographic film. The study has its origins in the work by Ferdinand Hurter and Vero Charles Driffield with early black-and-white emulsions....
of the image, that is, physical information about the light intensity and color of the scene.

Most raw image file formats store information sensed according to the geometry of the sensor's individual photo-receptive elements (sometimes called pixels), rather than points in the expected final image: sensors with hexagonal element displacement, for example, record information for each of their hexagonally-displaced cells, which a decoding software will eventually transform into the rectangular geometry during "digital developing".

File contents

Raw files contain, by necessity, the information required to produce a viewable image from the camera's sensor data. Although there is no standard raw file format, the structure of raw files often follow a common pattern, that is:

A short file header which typically contains an indicator of the byte-ordering
Endianness

In computing, endianness is the byte ordering used to represent some kind of data. Typical cases are the order in which integer values are stored as bytes in computer memory and the transmission order over a network or other medium....
of the file, a file identifier and an offset into the main file data
Camera sensor metadata
Metadata

Metadata is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema....
which is required to interpret the sensor image data. This includes the size of the sensor, the attributes of the CFA
Color filter array

In photography, a color filter array , or color filter mosaic , is a mosaic of tiny color filters placed over the pixel sensors of an to capture color information....
and its color profile
ICC profile

In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium ....
Image metadata
Metadata

Metadata is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema....
which is required for inclusion in any CMS
Content management system

A content management system is a computer application used to create, edit, manage, search and publish various kinds of Content . CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures....
environment or database
Database

A database is a structured collection of records or data that is stored in a computer system. The structure is achieved by organizing the data according to a database model....
. These include the exposure settings, camera/scanner/lens model, date (and, optionally, place) of shoot/scan, authoring information and other. Some raw files contain a standardized metadata section with data in EXIF
Exchangeable image file format

Exchangeable image file format is a specification for the file format used by digital cameras. The specification uses the existing JPEG, TIFF Rev....
format.
An image thumbnail
Thumbnail

Thumbnails are reduced-size versions of pictures, used to help in recognizing and organizing them, serving the same role for images as a normal text index does for words....
Optionally a reduced-size image in JPEG format, which can be used for a quick and less computing-intensive preview.
In the case of motion picture film scans, either the timecode, keycode
Keycode

Keycode may refer to:* keycode, the parcel of data generated when pressing a computer keyboard key ;* Eastman Kodak's Keykode , a bar coding placed at regular intervals on negative films to aid in identifying and counting frames....
or frame number in the file sequence
File sequence

In computing, as well as in non-computing contexts, a file sequence is a well-ordered, collection of files, usually supposed to be someway related to each other....
which represents the frame sequence in a scanned reel; this is a most important metadata item, because it allows the file to be ordered in a frame sequence
File sequence

In computing, as well as in non-computing contexts, a file sequence is a well-ordered, collection of files, usually supposed to be someway related to each other....
(without relying on its filename).
The sensor image data

Many raw file formats (including 3FR (Hasselblad), DCR, K25, KDC(Kodak), CR2 (Canon), ERF (Epson), MEF (Mamiya), MOS (Leaf), NEF (Nikon), ORF (Olympus), PEF (Pentax), RAW, RW2 (Panasonic) and ARW, SRF, SR2 (Sony)) are based on the TIFF file format. These files may deviate from the TIFF standard in a number of ways, including: the use of a non-standard file header, the inclusion of additional image tags and the encryption of some of the tagged data.

Panasonic's RAW files also contain information about necessary geometric distortion and chromatic aberration

Chromatic aberration

In optics, chromatic aberration is the failure of a lens to Focus all colors to the same point. It occurs because lenses have a different refractive index for different wavelengths of light ....
characteristics that should be made to the image.

The Adobe digital negative

Digital Negative (file format)

Sensor image data

Digital camera raw files contain the pixel

Pixel

In digital imaging, a pixel is the smallest item of information in an image. Pixels are normally arranged in a 2-dimensional grid, and are often represented using dots, squares, or rectangles....
data from a rectangular image sensor

Image sensor

An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices....
, the digital equivalent of photographic film

Photographic film

Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and of the film....
, usually at 12 or 14 bits per pixel. The sensor is almost invariably overlaid with a color filter array

Color filter array

In photography, a color filter array , or color filter mosaic , is a mosaic of tiny color filters placed over the pixel sensors of an to capture color information....
, usually a Bayer filter

Bayer filter

A Bayer filter mosaic is a color filter array for arranging RGB color model color filters on a square grid of photosensors. Its particular arrangement of color filters is used in most single-chip digital s used in digital cameras, camcorders, and scanners to create a color image....
, consisting of a mosaic of red, blue and green filters. Given that three colors fit uncomfortably in a rectangular grid, green was chosen to be doubly present, since the human eye is more sensitive to it. Green also often serves as the luminance channel, and as the dominant channel for in-camera black-and-white

Black-and-white

Black-and-white is a number of monochrome forms in visual arts. Most forms of visual technology start out in black and white, then slowly evolve into color as technology progresses....
conversions. To retrieve an image from a raw file, this mosaic of data must be converted into a full RGB image. This is often referred to as digital development.

One variation on the Bayer filter

Bayer filter

RGBE filter

In digital photography, the RGBE filter is an alternative color filter array to the Bayer filter . It similarly uses a mosaic of pixel filters, of red, green, blue and "emerald" , and so also requires demosaicing to produce a full-color image....
of the Sony Cyber-shot

Cyber-shot

Cyber-shot is a line of digital cameras made by Sony. The Cyber-shot range is well known for its proprietary InfoLithium battery pack, the trademark Carl_Zeiss_AG lenses and overall design....
DSC-F828, which exchanged the green in the RG rows with "emerald" (a blue-green

Blue-green

Blue-green is a name for a color with a mixture of blue and green. Some names used for different shades of this color are:* Teal for a dark shade of the color....
or cyan

Cyan

Cyan may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. In reference to the visible spectrum cyan is used to refer to the color obtained by mixing equal amounts of green and blue light or the removal of red from white light....
color). Other sensors, such as the Foveon X3 sensor

Foveon X3 sensor

The Foveon X3 sensor is a CMOS for digital cameras, designed by Foveon and manufactured by National Semiconductor and Dongbu Electronics. It uses an array of photosites, each of which consists of three vertically stacked photodiodes, that are organized in a two-dimensional grid....
capture information directly in RGB form, having three pixel sensors

Active pixel sensor

An active-pixel sensor , also commonly written active pixel sensor, is an consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier....
in each location, one for each color component; these camera RGB raw data still need to be processed to make an image file.

Flatbed

Image scanner

Film scanner

A film scanner is a device made for scanning photographic film directly into a computer without the use of any intermediate printmaking. They provide several benefits over using a flatbed scanner to scan in a print of any size — the photographer has direct control over cropping and aspect ratio from the original unmolested image on fi...
sensors are typically straight narrow RGB or RGBI (where "I" is infrared

Infrared

Infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves ....
) strips that are swept across an image; other than that, the remainder of the discussion about raw files applies to them as well. (Some scanners do not allow the host system access to the raw data at all, as a speed compromise. The raw data are processed very rapidly inside the scanner to select out the best part of the available dynamic range so only the result is passed to the computer for permanent storage, reducing the amount of data transferred and therefore the bandwidth requirement for any given speed of image throughput.)

Benefits

Nearly all digital cameras can process the image from the sensor

Charge-coupled device

A charge-coupled device is an analog signal shift register that enables the transportation of analog signals through successive stages , controlled by a clock signal....
into a JPEG file using settings for white balance, color saturation

Saturation (color theory)

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color....
, contrast

Contrast (vision)

Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view....
, and sharpness

Unsharp masking

Unsharp masking is an image manipulation technique now familiar to many users of digital image processing software, but it seems to have been first used in Germany in the 1930s as a way of increasing the acutance, or apparent sharpness, of photographic images....
that are either selected automatically or entered by the photographer before taking the picture. Cameras that support raw files save these settings in the file, but defer the processing. This results in an extra step for the photographer, so raw is normally only used when additional computer processing is intended. However, raw has numerous advantages over JPEG such as:

Higher image quality. Because all the calculations (such as applying the gamma curve, demosaicing, white balance, brightness
Brightness

Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target....
, contrast, etc...) used to generate pixel values (in RGB format for most images) are performed in one step on the base data, the resultant pixel values will be more accurate and exhibit less posterization.
Bypassing of undesired steps in the camera's processing, including sharpening
Sharpening

Sharpening is the process of creating or refining a sharp edge of appropriate shape on a tool or implement designed for cutting. Sharpening is done by grinding away material on the implement with an abrasive substance harder than the material of the implement, followed sometimes by processes to polish the sharp surface to increase smoothnes...
and noise reduction
Noise reduction

Noise reduction is the process of removing noise from a signal . Noise reduction techniques are conceptually very similar regardless of the signal being processed, however A priori and a posteriori knowledge of the characteristics of an expected signal can mean the implementations of these techniques vary greatly depending on the type of si...
JPEG images are typically saved using a lossy compression format (though a lossless JPEG compression is now available). Raw formats are typically either uncompressed or use lossless compression, so the maximum amount of image detail is always kept within the raw file.
Finer control. Raw conversion software allows users to manipulate more parameters (such as lightness
Lightness (color)

Lightness is a property of a color, or a dimension of a color space, that is defined in a way to reflect the subjective brightness perception of a color for humans....
, white balance, hue
Hue

Hue is one of the main properties of a color described with names such as "red", "yellow", etc. The two other main properties are lightness and colorfulness....
, saturation, etc...) and do so with greater variability. For example, the white point can be set to any value, not just discrete preset values like "daylight" or "incandescent".
Camera raw files have 12 or 14 bits of intensity information, not the gamma-compressed
Gamma correction

Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance or tristimulus values in video or still image systems....
8 bits stored in JPEG files (and typically stored in processed TIFF files); since the data is not yet rendered and clipped to a color space
Color space

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components ....
gamut
Gamut

In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors....
, more precision may be available in highlights, shadows, and saturated colors.
The color space
Color space

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components ....
can be set to whatever is desired.
Different demosaicing algorithms can be used, not just the one coded into the camera.
The contents of raw files include more information, and potentially higher quality, than the converted results, in which the rendering parameters are fixed, the color gamut is clipped, and there may be quantization
Quantization (image processing)

Quantization, involved in , is a lossy compression technique achieved by compressing a range of values to a single quantum value. When the number of discrete symbols in a given stream is reduced, the stream becomes more compressible....
and compression
Compression artifact

A compression artifact is the result of an aggressive data compression scheme applied to an , Sound recording, or video that discards some data that may be too complex to store in the available data-rate, or may have been incorrectly determined by an algorithm to be of little subjective importance, but is in fact objectionable to the view...
artifacts.
Large transformations of the data, such as increasing the exposure of a dramatically under-exposed photo, result in less visible artifacts when done from raw data than when done from already rendered image files. Raw data leave more scope for both corrections and artistic manipulations, without resulting in images with visible flaws such as posterization
Posterization

Posterization of an image occurs when a region of an image with a continuous gradation of tone is replaced with several regions of fewer tones, resulting in an abrupt change from one tone to another....
.

Drawbacks

Camera raw files are typically 2–6 times larger than JPEG files. Some raw formats do not use compression, some implement lossless data compression

Lossless data compression

Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data....
to reduce the size of the files without affecting image quality and others use lossy data compression

Lossy data compression

A lossy compression method is one where data compression and then decompressing it retrieves data that may well be different from the original, but is close enough to be useful in some way....
where quantization and filtering is performed on the image data. While use of raw formats avoids the compression artifacts inherent in JPEG, fewer images can fit on a given memory card

Memory card

A memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, Personal Digital Assistant and Mobile computers, telephones, music players, video game consoles, and other electronics....
. It also takes longer for the camera to write raw image files to the card, since they are larger, so fewer pictures can be taken in quick succession (affecting the ability to shoot, for example, a sports sequence).

There is still no widely accepted standard raw format. Three potential candidates for a standard format have been put forward, but none has been adopted by many major camera companies. Numerous different raw formats are currently in use and new raw formats keep appearing, while others are abandoned.

Because of the lack of a standard raw format, more specialized software may be required to open raw files than for standardized formats like JPEG or TIFF. Software developers have to frequently update their products to support the raw formats of the latest cameras.

The time taken in the image workflow is an important factor when choosing between raw and ready-to-use image formats.

Software support

Cameras that support raw files typically come with proprietary software

Proprietary software

Proprietary software is a term coined by advocates of the free software movement to describe computer software which is the legal property of one party....
for conversion of their raw image data into standard RGB images. Other processing and conversion programs

Computer program

Computer programs are Instruction for a computer. A computer requires programs to function. Moreover, a computer program does not run unless its instructions are executed by a Central processing unit; however, a program may communicate an Algorithm#Formalization of algorithms to people without running....
and plugin

Plugin

In computing, a plug-in consists of a computer program that interacts with a host application software to provide a certain, usually very specific, function "on demand"....
s are available from vendors that have either licensed the technology from the camera manufacturer or reverse-engineered

Reverse engineering

Reverse engineering is the process of discovering the technological principles of a device, object or system through analysis of its structure, function and operation....
the particular raw format and provided their own processing algorithms.

Raw file formats are proprietary, and differ greatly from one manufacturer to another, and sometimes between cameras made by one manufacturer. Adobe Photoshop

Adobe Photoshop

Adobe Photoshop, or simply Photoshop, is a Graphics software developed and published by Adobe Systems. It is the current and primary Market dominance for commercial Raster graphics and manipulation, and is the flagship product of Adobe Systems....
CS2 and CS3 (and most recently, CS4) contain extensive support of raw formats as does Adobe Photoshop Lightroom. In addition, Adobe has proposed its own Digital Negative file format

Digital Negative (file format)

In digital photography, the Digital Negative file format is a royalty free RAW image format designed by Adobe Systems. Its specification was announced on September 27, 2004....
(DNG). As of 2006, several camera manufacturers have started to announce support for DNG in newer camera models, including Leica

Leica

Leica is a camera produced by a Germany company of the same name. The company, formerly Ernst Leitz Gmbh, is now three companies: Leica Camera AG, Leica Geosystems AG, and Leica Microsystems AG, each producing cameras, geosurvey equipment and microscopes, respectively....
, Samsung, Ricoh

Ricoh

or Ricoh, is a Japanese company that was established on February 6, 1936 as , a company in the RIKEN zaibatsu. It is headquartered in the Ricoh Building in Chuo, Tokyo, Tokyo....
, Pentax

Pentax

is a wholly owned division and brand name of Hoya Corporation. It succeeds to the business operations of , which was merged with and into Hoya on March 31, 2008....
(native camera support) and Hasselblad

Hasselblad

Victor Hasselblad AB is a Sweden manufacturer of medium-format cameras and photographic equipment based in Gothenburg, Sweden.The company is best known for the product of medium-format cameras it has produced since World War II....
(export). The Leica Digital-Modul-R (DMR) was first to use DNG as its native format.

Microsoft's Digital Image 2006 recognizes and organizes raw image formats such as .crw, .cr2, and .nef, which are file formats produced by Canon and Nikon, but that product was discontinued in 2007.

For Windows XP

Windows XP

Windows XP is a line of operating systems produced by Microsoft for use on personal computers, including home and business desktops, laptop, and media centers....
, there is a free download available that integrates viewing and printing into other included photo tools, but it is not supported by Microsoft.

Windows XP and Vista both support the WIC

Windows Imaging Component

The Windows Imaging Component is a Component Object Model based imaging codec framework introduced in Windows Vista and Windows XP#Service Pack 3 for working with and processing digital images and image metadata....
codec standard. Products such as Windows Photo Gallery

Windows Photo Gallery

Windows Photo Gallery is a photo management, tagging, and editing tool development by Microsoft, and is included with all editions of Windows Vista....
, Windows Live Photo Gallery

Windows Live Photo Gallery

Windows Live Photo Gallery is a photo management and sharing application released as a part of Microsoft Windows Live initiative. It is an upgraded version of Windows Photo Gallery, which is a part of Windows Vista....
and FastPictureViewer Professional

Fast Picture Viewer

FastPictureViewer is a commercial for Windows 7, Windows Vista and Windows XP. Its aim is to facilitate quick review and rating of large quantities of digital images in the early steps of the digital workflow, with an emphasis on simplicity and speed....
can view raw formats for which the necessary WIC

Windows Imaging Component

Nikon

, also known as Nikon or Nikon Corp., is a multinational corporation headquartered in Tokyo, Japan specializing in optics and imaging....
, Sony

Sony

Olympus Corporation

is a Japanese company specializing in optics and imaging. Olympus was established on October 12, 1919, initially specialized in microscope and thermometer businesses....
and Pentax

Pentax

is a wholly owned division and brand name of Hoya Corporation. It succeeds to the business operations of , which was merged with and into Hoya on March 31, 2008....
have released WIC codecs although some manufactures are only providing codec support for the 32bit versions of Vista. A commercial DNG

Digital Negative (file format)

In digital photography, the Digital Negative file format is a royalty free RAW image format designed by Adobe Systems. Its specification was announced on September 27, 2004....
codec is also available from Ardfry Imaging.

In 2005, Apple Computer

Apple Computer

Apple Inc., formerly Apple Computer Inc., is an United States multinational corporation which designs and manufactures consumer electronics and software products....
introduced several products which offered raw file support. In January, Apple released iPhoto

IPhoto

iPhoto is a Application software made by Apple Inc. exclusively for their Mac OS X operating system. The first version of iPhoto was released in 2002....
5, which offered basic support for viewing and editing many raw file formats. In April, Apple introduced a new version of its operating system, Mac OS X v10.4

Mac OS X v10.4

Mac OS X version 10.4 ?Tiger? was the fifth Software version of Mac OS X, Apple Inc. desktop and server operating system for Macintosh computers....
, which added raw support directly to the operating system, as part of the ImageIO framework, which adds raw support automatically to the majority of Mac OS X applications both from Apple (such as Preview, Mac OS X's PDF and image viewing application and Aperture, a photo post-production software package for professionals) as well as all third party applications which make use of the ImageIO frameworks. Semi-regular updates to OS X generally include updated support for new raw file formats introduced in the intervening months by camera makers.

There are many other "raw workflow applications" designed to provide efficient processing and post-processing of raw images, including Helicon Filter

Helicon Filter

Helicon Filter, also referred to as Helicon, Filter, or as HF, is a proprietary software Commerce and freeware raster graphics editor for Microsoft Windows, similar to such programs as Adobe Photoshop and the open source GIMP, developed and published by Helicon Soft Ltd....
, Phase One's

Phase One

Phase One is a Denmark company specializing in high-end digital photography equipment. It manufactures digital backs for Medium format and large format cameras, highly popular among fashion and still life photographers....
Capture One and Bibble Labs' Bibble Pro

Bibble (software)

Bibble is a digital imaging program for multiple platforms by Bibble Labs, designed to assist photographers in post-production work and efficient optimization of images created in the RAW image format....
. Like Apple Aperture, Adobe Photoshop and Lightroom, LaserSoft Imaging's SilverFast

SilverFast

SilverFast is software for and , developed by LaserSoft Imaging....
, and PhotoLine, these programs provide sophisticated controls for processing the information stored in the raw file and converting raw files to JPEG or TIFF. Picasa

Picasa

Picasa is a software application for organizing and editing digital photographys, originally created by Idealab and owned by Google since 2004. "Picasa" is a blend of the name of Spanish painter Pablo Picasso, the phrase mi casa for "my house" and "pic" for pictures . In July 2004, Google acquired Picasa and began offering...
, a free image editing and cataloguing program from Google

Google

Google Inc. is an United States public company, earning revenue from AdWords related to its Google search, Gmail, Google Maps, Google Apps, Orkut, and YouTube services as well as selling advertising-free versions of the Google Search Appliance....
, can read and display many raw formats, but like iPhoto, Picasa provides only limited tools for processing the data in a raw file.

A portable open source

Open source

Dcraw

Unix

Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
).

UFRaw

UFRaw

UFRaw is an application which can read and manipulate photographs in raw image formats, as created by many digital cameras. UFRaw is available both as a stand-alone utility and as a GIMP plugin....
is free software based on dcraw. It can be used as a GIMP

GIMP

The GIMP is a free software, raster graphics editor used to process digital graphics and photographs. Typical uses include creating graphics and logos, resizing and cropping photos, altering colors, combining multiple images, removing unwanted image components, and converting between different image formats....
plugin and is available for most operating systems.

is a raw converter for Mac OS X (10.4 or 10.5 only), supporting almost all available digital waw formats. RPP is not a full featured photo processing package, rather it supports some carefully chosen photographic operations.

ExifTool

ExifTool

ExifTool is free software used for reading, writing, and manipulating image, audio and video metadata. It is platform independent and is both a Perl library and command-line application....
supports the reading, writing and editing of metadata in raw image files. ExifTool supports many different types of metadata including EXIF, GPS, IPTC

IPTC Information Interchange Model

The Information Interchange Model is a file structure and set of metadata attributes that can be applied to text, s and other media types. It was developed in the early 1990s by the International Press Telecommunications Council to expedite the international exchange of news among newspapers and news agencies....
, XMP

Extensible Metadata Platform

The Adobe Extensible Metadata Platform is a standard for processing and storing standardized and proprietary metadata, created by ADBE.XMP standardizes the definition, creation, and processing of extensible metadata....
, JFIF

JPEG File Interchange Format

The JPEG File Interchange Format is an standard. It is a format for exchanging JPEG encoded files compliant with the JPEG standard. It solves some of JIFs limitations in regard to simple JPEG encoded file interchange....
, GeoTIFF

GeoTIFF

GeoTIFF is a public domain Metadata standard which allows Georeference information to be embedded within a TIFF file. The potential additional information includes projections, coordinate systems, ellipsoids, datum s, and everything else necessary to establish the exact spatial reference for the file....
, ICC Profile

ICC profile

In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium ....
, Photoshop IRB, FlashPix

FlashPix

FlashPix is a Bitmap Computer graphics file format where the image is saved in more than one Display resolution. Though this makes it larger even than a TIFF file, when a request is sent for the file by a Web browser only the resolution required for the current screen resolution is sent to the browser; this therefore saves on Bandwidth and d...
, AFCP and ID3, as well as the maker notes of many digital cameras.

RawShooter Essentials 2005/6 was freeware software developed by Pixmantec. In 2006 Adobe acquired the assets of Pixmantec. RawShooter Essentials is no longer being updated (The last update added support for the Canon 5D and the Nikon D200

Nikon D200

The Nikon D200 is a 10.2 megapixel digital single-lens reflex camera that falls between entry-level and midrange DSLR cameras such as the Nikon D40, Nikon D40x, and Nikon D80 and high-end models such as the Nikon D2Hs and Nikon D2Xs....
). It could still be downloaded for free until Adobe's Lightroom 1.0 was released in March 2007. The software was fully featured, including wide support for various raw formats, file priority sorting and batch processing. Light Crafts' LightZone

LightZone

LightZone is a digital photo editor software application from Light Crafts. Its main purpose is to handle the workflow when handling images in various RAW image format formats....
photo editing software provides the ability to edit many raw formats natively. Most tools are raw converters, but LightZone allows a user to edit a raw file as if it were TIFF or JPEG.

Standardization

In 2004, Adobe Systems

Adobe Systems

Adobe Systems Incorporated is an United States computer Computer software company headquartered in San Jose, California, USA. The company has historically focused upon the creation of multimedia and creativity software products, with a more-recent foray into rich Internet application software development....
developed and promoted a standardized raw image format called DNG

Digital Negative (file format)

In digital photography, the Digital Negative file format is a royalty free RAW image format designed by Adobe Systems. Its specification was announced on September 27, 2004....
(Digital Negative); this has been received enthusiastically by open-source developers but has received little support from major camera makers other than Pentax

Pentax

is a wholly owned division and brand name of Hoya Corporation. It succeeds to the business operations of , which was merged with and into Hoya on March 31, 2008....
and Samsung; their Pentax K20D

Pentax K20D

The Pentax K20D and similar Samsung GX-20 are 14.6 megapixel digital single-lens reflex cameras, announced on January 24, 2008. The K20D is available from US retailers ....
/Samsung GX-20 and Pentax K200D

Pentax K200D

The Pentax K200D is a 10.2 megapixel digital single-lens reflex camera, announced on January 24, 2008 along with the higher-end Pentax K20D.The K200D is the successor to the well-reviewed K100D, K110D, and K100D Super 6-megapixel DSLRs from Pentax....
digital single-lens reflex cameras can shoot directly into DNG format, as could the now-discontinued Pentax K10D

Pentax K10D

The Pentax K10D and similar Samsung GX-10 are 10.2 megapixel digital single-lens reflex cameras launched in late 2006. They were developed in a collaboration between Pentax of Japan and Samsung of Korea....
/Samsung GX-10.

Two other would-be standards for digital negatives in the digital cinema industry are the OpenEXR

OpenEXR

DPX

Digital Picture Exchange is a common file format for digital intermediate and visual effects work and is an American National Standards Institute/SMPTE standard ....
formats. The much newer OpenEXR format has good metadata support and offers more effective compression

OpenEXR

OpenEXR is a high dynamic range imaging , released as an open standard along with a set of software tools created by Industrial Light and Magic , released under a free software license similar to the BSD license....
(both lossless as well as lossy) than the DNG format. Using OpenEXR to store RAW camera data has been discussed on the OpenEXR mailing list.

Microsoft

Microsoft

Microsoft Corporation is a multinational corporation computer technology corporation that develops, manufactures, licenses, and supports a wide range of computer software products for computing devices....
has submitted its HD Photo specification for ratification as JPEG XR for use as a raw format.

Processing

To be viewed or printed, the output from a camera's image sensor

Image sensor

An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices....
has to be processed, that is, converted to a photographic rendering of the scene, and then stored in a standard raster graphics

Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
format such as JPEG

JPEG

In computing, JPEG is a commonly used method of for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality....
. This processing, whether done in-camera or later in a raw file converter, involves a number of operations, typically including:

defective pixel
Defective pixel

Defective pixels are pixels on a liquid crystal display not performing as expected. ISO 13406-2 distinguishes between three different types of defective pixels:...
removal – replacing data in known bad locations with interpolations from nearby locations
demosaicing
Demosaicing

A demosaicing algorithm is a digital image processing used to reconstruct a full color image from the incomplete color samples output from an overlaid with a a color filter array ....
– interpolating the partial raw data received from the color-filtered
Color filter array

In photography, a color filter array , or color filter mosaic , is a mosaic of tiny color filters placed over the pixel sensors of an to capture color information....
image sensor into a matrix of colored pixels.
noise reduction
Noise reduction

Noise reduction is the process of removing noise from a signal . Noise reduction techniques are conceptually very similar regardless of the signal being processed, however A priori and a posteriori knowledge of the characteristics of an expected signal can mean the implementations of these techniques vary greatly depending on the type of si...
– trading off detail for smoothness by removing small fluctuations
color translation – converting from the color space
Color space

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components ....
defined by the spectral sensitivities
Spectral sensitivity

Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal....
of the image sensor to an internal working color space such as CIE XYZ
white balancing – accounting for color temperature
Color temperature

Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, and other fields....
of the light that was used to take the photograph
color space
Color space

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components ....
transformation – conversion from the internal working color space to the output color space (typically sRGB for JPEG)
bit-depth
Color depth

Color depth or bit depth, is a computer graphics term describing the number of bits used to represent the color of a single pixel in a Raster graphicsped image or video frame buffer....
reduction and gamma compression
Gamma correction

Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance or tristimulus values in video or still image systems....
– for example for JPEG files the 10 or more bits per pixel of color data are nonlinearly reduced to 8 bits per pixel.
compression
Image compression

Image compression is the application of Data compression on digital images. In effect, the objective is to reduce redundancy of the image data in order to be able to store or data transmission data in an efficient form....
– for example JPEG compression
JPEG

In computing, JPEG is a commonly used method of for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality....

Note that demosaicing

Demosaicing

A demosaicing algorithm is a digital image processing used to reconstruct a full color image from the incomplete color samples output from an overlaid with a a color filter array ....
is only performed for CFA

Color filter array

In photography, a color filter array , or color filter mosaic , is a mosaic of tiny color filters placed over the pixel sensors of an to capture color information....
sensors; it is not required for 3CCD or Foveon X3

Foveon X3 sensor

The Foveon X3 sensor is a CMOS for digital cameras, designed by Foveon and manufactured by National Semiconductor and Dongbu Electronics. It uses an array of photosites, each of which consists of three vertically stacked photodiodes, that are organized in a two-dimensional grid....
sensors.

Cameras and image processing software may also perform additional processing to improve image quality, for example:

removal of systematic noise – bias frame
Bias frame

Much like a dark frame, a bias frame is an image obtained from an optical Charge-coupled device or Active pixel sensor sensor, with no actual exposure time....
subtraction and flat-field correction
Flat-field correction

Flat-field correction is a technique used to improve quality in digital imaging. The goal is to remove artifacts from 2-D images that are caused by variations in the pixel-to-pixel sensitivity of the detector and/or by distortions in the optical path....
dark frame
Dark frame

A dark frame is a photography technique to identify in a Charge-coupled device. This is done by recording without exposing the CCD, usually by leaving the Shutter closed and putting the CCD in a dark room....
subtraction
optical correction – lens distortion correction, vignetting
Vignetting

In photography and optics, vignetting is a reduction of an image's brightness or saturation at the periphery compared to the image center. A similar effect occurs when filming projected images or movies off a projection screen, the so-called hotspot, defining a cheap home-movie look where no proper telecine is used....
correction, and color fringing
Purple fringing

In photography, and particularly in digital photography, purple fringing is the term for an out-of-focus purple ghost image on a photograph. Images taken with high-contrast boundary areas involving daylight or gas discharge lamps are particularly susceptible, since chromatic aberration is worst for the shortest wavelengths that a camera i...
correction
contrast enhancement
Display contrast

Contrast in visual perception is the difference in appearance of two or more parts of a field seen simultaneously or successively .Contrast in physics is a quantity intended to correlate with the perceived brightness contrast, usually defined by one of a number of formulae which involve e.g....
increasing visual acuity
Visual acuity

Visual acuity is acuteness or clearness of visual perception, especially form vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
by unsharp masking
Unsharp masking

Unsharp masking is an image manipulation technique now familiar to many users of digital image processing software, but it seems to have been first used in Germany in the 1930s as a way of increasing the acutance, or apparent sharpness, of photographic images....
dynamic range compression
High dynamic range imaging

In , computer graphics, and photography, high dynamic range imaging is a set of techniques that allows a greater dynamic range#Photography of luminances between light and dark areas of a scene than normal digital imaging techniques....
– lighten shadow regions without blowing out highlight regions

When a camera saves a raw file it defers most of this processing; typically the only processing performed is the removal of defective pixels (the DNG specification requires that defective pixels are removed before creating the file). Some camera manufacturers do additional processing before saving raw file; for example, Nikon has been criticized by astrophotographers

Astrophotography

Astrophotography is a specialized type of photography that entails making photographs of astronomical objects in the sky such as the Moon, Sun, planets, stars, and deep sky objects such as star clusters and galaxies....
for applying noise reduction before saving the raw file.

Some raw formats also allow nonlinear quantization

Quantization (image processing)

Quantization, involved in , is a lossy compression technique achieved by compressing a range of values to a single quantum value. When the number of discrete symbols in a given stream is reduced, the stream becomes more compressible....
. This nonlinearity allows the compression of the raw data without visible degradation of the image by removing invisible and irrelevant information from the image. Although noise is discarded this has nothing to do with (visible) noise reduction.

External links

Adobe: "; background on how camera sensors treat raw files
: a working group
Working Group

Working Group can mean:*Working group, an interdisciplinary group of researchers; or*Working Group , kennel club designation for certain purebred dog breeds; or...
of photographers, software engineers and other people interested in advocating the open documentation of digital camera raw files
Atkins, Bob: ""; common file formats compared.
Roling, John: ""; explanation of and arguments for raw formats.
Goldstein, Jim M.: ""; an editorial.
Clevy, Laurent: ""

RAW image format

Rationale

File contents

Sensor image data

Benefits

Drawbacks

Software support

Standardization

Processing

See also

External links