JPEG-HDR
Encyclopedia
JPEG-HDR is an extension to the standard JPEG image file format
allowing it to store high dynamic range images
.
inside a standard JPEG
file. This reduces the file size required to store HDR images compared to other HDR formats such as floating point
TIFF
and RGBE
. It does this by first converting the image into a tone mapped
version and storing a reconstructive multiplier image in APP11 markers in the same JPEG file. Ordinary viewing software will ignore the multiplier image allowing anyone to see the tone mapped version of the image.
in 2007).
JPEG File Interchange Format
The JPEG File Interchange Format is an image file format standard. It is a format for exchanging JPEG encoded files compliant with the JPEG Interchange Format standard. It solves some of JIFs limitations in regard to simple JPEG encoded file interchange...
allowing it to store high dynamic range images
High dynamic range imaging
In image processing, computer graphics, and photography, high dynamic range imaging is a set of techniques that allows a greater dynamic range between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods...
.
Overview
JPEG-HDR was created by Greg Ward and Maryann Simmons as a way to store high dynamic range imagesHigh dynamic range imaging
In image processing, computer graphics, and photography, high dynamic range imaging is a set of techniques that allows a greater dynamic range between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods...
inside a standard JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
file. This reduces the file size required to store HDR images compared to other HDR formats such as floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
TIFF
Tagged Image File Format
TIFF is a file format for storing images, popular among graphic artists, the publishing industry, and both amateur and professional photographers in general. As of 2009, it is under the control of Adobe Systems...
and RGBE
RGBE image format
RGBE is an image format invented by Gregory Ward Larson. It stores pixels as one byte each for RGB values with a one byte shared exponent. Thus it stores four bytes per pixel....
. It does this by first converting the image into a tone mapped
Tone mapping
Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another in order to approximate the appearance of high dynamic range images in a medium that has a more limited dynamic range...
version and storing a reconstructive multiplier image in APP11 markers in the same JPEG file. Ordinary viewing software will ignore the multiplier image allowing anyone to see the tone mapped version of the image.
Support
Software programs that support JPEG-HDR's include Photosphere (by Greg Ward) and pfstools. A Software Encoder was available from BrightSide Technologies (formerly Sunnybrook Technologies, acquired by Dolby LaboratoriesDolby Laboratories
Dolby Laboratories, Inc. , often shortened to Dolby Labs, is an American company specializing in audio noise reduction and audio encoding/compression.-History:...
in 2007).