ColorSync
Encyclopedia
ColorSync is Apple Inc's color management
API for the Mac OS
and Mac OS X
.
to develop a cross-platform
profile format which became part of ColorSync 2.0. The system Color Management Module (CMM) was "LinoColorCMM", which was developed by Linotype-Hell AG (now part of Heidelberger Druckmaschinen
AG). The same CMM was used in Microsoft Windows 2000 and XP under the rubric of "Image Color Management" (ICM). Apple, with the help of Adobe
had ported ColorSync 2.0 and its SDK to Microsoft Windows
. With ColorSync 3.0, the Windows version which was initially planned was discontinued. ColorSync 4.0 is the latest version, introduced in Mac OS X
10.1.
is a very complex and subtle process, and different devices have widely different color gamut
s or ranges of color they can display. To deal with these issues, ColorSync provides several different methods of doing color matching. For instance, perceptual matching tries to preserve as closely as possible the relative relationships between colors, even if all the colors must be systematically distorted in order to get them to fit within the gamut of the destination device. Because the human eye is more sensitive to color difference
s rather than absolute color
s, this method tends to produce the best-looking results, subjectively speaking, for many common uses, but there are other methods that work better in some cases.
. All image input and output devices (scanners, printers, displays) have to be characterized by providing an ICC profile
that defines how their color information is to be interpreted relative to this reference color space. This profile might be provided by the device manufacturer, but for better quality results, it might be generated by performing actual measurements on the device with a colorimeter
. Thus, when an image is scanned on a scanner, the image file will include a copy of the scanner's profile to characterize the meaning of its color information. Then, before the image is sent to an output device, a matching process converts the color information at the time of rendering from the source profile (that attached to the image) to the destination profile (that attached to the output device) so that the resulting colors print or display as closely as possible to the original image.
. It is used for management of color profiles and filters used in Apple's PDF workflow
, or applying filters to PDF documents.
The interface is composed of two parts: the document browser and the utility window. The document browser lets you zoom in and out of an image or apply a Filter to it. The utility window has several options: Profile First Aid, Profiles, Devices, Filters and Calculator.
Profile First Aid allows you to repair ColorSync color profiles so they conform to the International Color Consortium
specification.
Profiles allows you to browse the profiles installed on your system, grouped by location, class or space, and graphically compare any two profiles.
The profile map is displayed as a rotatable, scalable 3D object and can be plotted in CIELAB, CIELUV, Yxy
, Yuv
and CIEXYZ
.
The Devices section allows you to see a list of all registered ColorSync devices such as your displays and printers, and see what ColorSync profile is applied to each one. You can also override the default setting.
The Filters section allows you to build and modify PDF filters that are available to the rest of the operating system. Each filter can be set to appear in one of three domains: Application, PDF Workflows, and Printing.
Filters set to Printing will appear in the drop-down menu under the "Save as PDF..." button in the standard Mac OS X print dialog box. Filters set to PDF Workflow will appear in the Quartz
Filters drop-down menu in the ColorSync section of a print dialog box.
The default filters that ship with Mac OS X are:
User-created filters can have color management, image effects, PDF retouch, domain selection and comments.
The Color Management section allows assigning a profile, choosing a default profile, rendering intent, converting to a profile or intermediate transform.
The Intermediate Transform section allows adjustment of brightness, tint, hue, saturation, bilevel (high pass filter) or profile assignment, to either grayscale
, RGB or CMYK, or all data in the file. This can be applied to either text, graphics, images or shading.
Complex filters can be created by stacking multiple effects. Any changes made to the PDF file can then be saved as a new PDF file.
Calculator can convert between RGB, CMYK and other color value schemes, and features an interactive color-picker for identifying a color on the screen, duplicating a feature of another bundled utility, DigitalColor Meter
.
Color management
In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media.The primary goal of color...
API for the Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
and Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
.
Version history
Apple developed the original 1.0 version of ColorSync as a Mac-only architecture, which made it into an operating system release in 1993. In the same year, Apple co-founded the International Color ConsortiumInternational Color Consortium
The International Color Consortium was formed in 1993 by eight industry vendors in order to create a universal color management system that would function transparently across all operating systems and software packages....
to develop a cross-platform
Cross-platform
In computing, cross-platform, or multi-platform, is an attribute conferred to computer software or computing methods and concepts that are implemented and inter-operate on multiple computer platforms...
profile format which became part of ColorSync 2.0. The system Color Management Module (CMM) was "LinoColorCMM", which was developed by Linotype-Hell AG (now part of Heidelberger Druckmaschinen
Heidelberger Druckmaschinen
Heidelberger Druckmaschinen AG is a German precision mechanical engineering company with head offices in Heidelberg . It is a manufacturer of offset printing presses sold globally. The company has a worldwide market share of more than 47% in this area and is the largest global manufacturer of...
AG). The same CMM was used in Microsoft Windows 2000 and XP under the rubric of "Image Color Management" (ICM). Apple, with the help of Adobe
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
had ported ColorSync 2.0 and its SDK to Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
. With ColorSync 3.0, the Windows version which was initially planned was discontinued. ColorSync 4.0 is the latest version, introduced in Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
10.1.
Overview
Human color perceptionColor vision
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit...
is a very complex and subtle process, and different devices have widely different color gamut
Gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...
s or ranges of color they can display. To deal with these issues, ColorSync provides several different methods of doing color matching. For instance, perceptual matching tries to preserve as closely as possible the relative relationships between colors, even if all the colors must be systematically distorted in order to get them to fit within the gamut of the destination device. Because the human eye is more sensitive to color difference
Color difference
The difference or distance between two colors is a metric of interest in color science. It allows people to quantify a notion that would otherwise be described with adjectives, to the detriment of anyone whose work is color critical...
s rather than absolute color
Absolute color space
In color science, there are two meanings of the term absolute color space:* A color space in which the perceptual difference between colors is directly related to distances between colors as represented by points in the color space....
s, this method tends to produce the best-looking results, subjectively speaking, for many common uses, but there are other methods that work better in some cases.
Profiles and color spaces
As dictated by the ICC system, the profile connection space in ColorSync is the CIE XYZ color spaceCIE 1931 color space
In the study of color perception, one of the first mathematically defined color spaces is the CIE 1931 XYZ color space, created by the International Commission on Illumination in 1931....
. All image input and output devices (scanners, printers, displays) have to be characterized by providing an 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...
that defines how their color information is to be interpreted relative to this reference color space. This profile might be provided by the device manufacturer, but for better quality results, it might be generated by performing actual measurements on the device with a colorimeter
Colorimeter
For articles on Colorimeter see:* Colorimeter * Tristimulus colorimeter...
. Thus, when an image is scanned on a scanner, the image file will include a copy of the scanner's profile to characterize the meaning of its color information. Then, before the image is sent to an output device, a matching process converts the color information at the time of rendering from the source profile (that attached to the image) to the destination profile (that attached to the output device) so that the resulting colors print or display as closely as possible to the original image.
ColorSync Utility
ColorSync Utility is software that ships with Mac OS XMac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
. It is used for management of color profiles and filters used in Apple's PDF workflow
Workflow
A workflow consists of a sequence of connected steps. It is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work...
, or applying filters to PDF documents.
The interface is composed of two parts: the document browser and the utility window. The document browser lets you zoom in and out of an image or apply a Filter to it. The utility window has several options: Profile First Aid, Profiles, Devices, Filters and Calculator.
Profile First Aid allows you to repair ColorSync color profiles so they conform to the International Color Consortium
International Color Consortium
The International Color Consortium was formed in 1993 by eight industry vendors in order to create a universal color management system that would function transparently across all operating systems and software packages....
specification.
Profiles allows you to browse the profiles installed on your system, grouped by location, class or space, and graphically compare any two profiles.
The profile map is displayed as a rotatable, scalable 3D object and can be plotted in CIELAB, CIELUV, Yxy
CIE 1931 color space
In the study of color perception, one of the first mathematically defined color spaces is the CIE 1931 XYZ color space, created by the International Commission on Illumination in 1931....
, Yuv
YUV
YUV is a color space typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, thereby typically enabling transmission errors or compression artifacts to be more efficiently...
and CIEXYZ
CIE 1931 color space
In the study of color perception, one of the first mathematically defined color spaces is the CIE 1931 XYZ color space, created by the International Commission on Illumination in 1931....
.
The Devices section allows you to see a list of all registered ColorSync devices such as your displays and printers, and see what ColorSync profile is applied to each one. You can also override the default setting.
The Filters section allows you to build and modify PDF filters that are available to the rest of the operating system. Each filter can be set to appear in one of three domains: Application, PDF Workflows, and Printing.
Filters set to Printing will appear in the drop-down menu under the "Save as PDF..." button in the standard Mac OS X print dialog box. Filters set to PDF Workflow will appear in the Quartz
Quartz (graphics layer)
Quartz specifically refers to a pair of Mac OS X technologies, each part of the Core Graphics framework: Quartz 2D and Quartz Compositor. It includes both a 2D renderer in Core Graphics and the composition engine that sends instructions to the graphics card...
Filters drop-down menu in the ColorSync section of a print dialog box.
The default filters that ship with Mac OS X are:
- Black & White
- Blue Tone
- Create Generic PDFX-3 Document
- Gray Tone
- Lightness Decrease
- Lightness Increase
- Reduce File Size
- Sepia Tone.
User-created filters can have color management, image effects, PDF retouch, domain selection and comments.
The Color Management section allows assigning a profile, choosing a default profile, rendering intent, converting to a profile or intermediate transform.
The Intermediate Transform section allows adjustment of brightness, tint, hue, saturation, bilevel (high pass filter) or profile assignment, to either grayscale
Grayscale
In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information...
, RGB or CMYK, or all data in the file. This can be applied to either text, graphics, images or shading.
Complex filters can be created by stacking multiple effects. Any changes made to the PDF file can then be saved as a new PDF file.
Calculator can convert between RGB, CMYK and other color value schemes, and features an interactive color-picker for identifying a color on the screen, duplicating a feature of another bundled utility, DigitalColor Meter
DigitalColor Meter
DigitalColor Meter is a utility for measuring and displaying the colour values of pixels displayed on the screen of a Macintosh computer.The utility presents a "window" onto the screen which includes a cursor which by default is 1 × 1 pixel in size...
.