|Color Management in Photoshop 5.x
The RGB Setup dialog box has a pop-up menu from where you choose your working color space for RGB files.
The RGB Setup dialog box also has pop-up menus for choosing White Point (indicated by the color temperature) and Primaries (the RGB values that describe a given color space). These are automatically set when you make your color space selection:
|Note: Monitor RGB always displays White Point and Primaries values that are identical to the ones you set in Adobe Gamma.
Photoshop 5.x includes the widest possible variety of RGB industry standards so that files can be color-managed regardless of their final destinationbe it print, video, film, television, or the Web. Even if color management is not yet implemented in some of these fields, files from Photoshop will be ready for them when it is.
Your choice of working space should be determined by the type of environment you work in. If you are working in a fully ICC-aware workflow (where files will be placed into ICC-aware applications such as Adobe PageMaker 6.5, Illustrator 8.0, and InDesign), you can edit and save RGB files with embedded profiles. If you are working with non ICC-aware applications, you will usually need to convert your files to CMYK in Photoshop if you intend to print separations.
sRGB is a standard promoted primarily by Hewlett-Packard and Microsoft. It reflects the standards for HDTV broadcast (Gamma=2.2, Primaries=HDTV, White Point=6500K).
One of the reasons to use sRGB is that Hewlett-Packard is promoting a workflow in which hardware devices such as scanners, non-PostScript printers, and Web browsers will be optimized for RGB data in the sRGB space. If you are using such devices, sRGB will provide the simplest workflow.
sRGB reflects the characteristics of the average PC monitor. If you are producing graphics to be viewed on the Web, sRGB will reflect what most viewers see. The downside to sRGB is that it has a limited color gamut and cannot represent as many colors as other color spaces. It is not a good choice for professional prepress users since too much of the CMYK gamut lies outside of it.
Apple RGB is based on the classic Apple 13" Trinitron monitor (Gamma=1.8, Primaries=Trinitron, White Point=6500K). This space represents many legacy files in the desktop publishing world simply because applications such as Adobe Illustrator and Adobe Photoshop used it as their default for RGB in the past. Its gamut isn't much larger than that of sRGB.
SMPTE-C is the current standard for broadcast television in the United States. If you are doing work targeted at US broadcast, SMPTE-C is a good choice.
PAL/SECAM is the European broadcast standard. If you are doing work targeted at European broadcast, PAL/SECAM is a good choice.
ColorMatch RGB represents an idealized version of the Radius PressView monitor. This monitor is common in the prepress world and the space has a reasonably broad gamut. If you are working in a PressView based workflow, using ColorMatch RGB will provide a reasonably large gamut while also providing a fair amount of color consistency, even with ICC-unaware applications.
Adobe RGB (1998) provides a larger gamut than ColorMatch RGB and is potentially a better space for prepress work if you want to access a broader range of colors. The downside is that it also includes more unprintable colors (that is, colors that are outside the CMYK gamut).
|Note: In Photoshop 5.x, Adobe RGB (1998) was called SMPTE-240M. Any references to SMPTE-240M you may encounter in other Photoshop 5.x documents apply to Adobe RGB (1998).
Wide Gamut RGB provides a very wide range of colors by using spectrally pure primaries. The downside is that most of the colors in this gamut cannot be displayed on standard computer monitors or printed. When editing a file, colors are often forced into the display space (clipped) and, consequently, your color adjustments may not appear as visible changes on the screen.
Monitor RGB/Simplified Monitor RGB Photoshop 5.x includes an option to set the working RGB space to a version of the current monitor space. This option makes Photoshop 5.x behave like older versions with regard to color management, though it now writes color tags into files and reads those tags when opening files. This is useful if the other applications in your workflow are ICC-unaware.
Whether Monitor RGB or Simplified Monitor RGB is available to you depends on the complexity of your actual monitor profile. For example, profiles with three gamma curves (one each for red, green, and blue) will be simplified to a single gamma.
CIE RGB is an outdated standard that Photoshop 5.x includes since it is still, though rarely, referenced in color work.
NTSC (1953) is another outdated standard, in this case for video production. Like CIE RGB, it may be still be used in some cases, but is rare.
To convey the relationship between the various types of RGB, the illustration below shows three representative gamuts: Wide Gamut RGB, sRGB, and Adobe RGB (1998). These are seen against the backdrop of the CIE XYZ Chromaticity diagram (which represents the whole gamut of color visible to the human eye):
When the Display Using Monitor Compensation check box is selected, Photoshop displays your image using the active monitor profile. If you deselect this option, Photoshop sends RGB data unaltered to the screenthe way that a non ICC-savvy application would display the image. Note that deselecting it will also affect the display of non-RGB imagesyou won't be able to "soft proof" CMYK files with this turned off. For good color management, leave it on.