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Standard working spaces were introduced in the late 1990s with Photoshop 5. A "standard" working space, Apple RGB, was used in Photoshop 4, but it could not be changed by the user.

Standard working spaces are defined by ICC profiles. Standard spaces common in the graphic arts (in order of increasing size) are sRGB, ColorMatch RGB, and Adobe RGB. Each standard RGB working space profile has a gamma (contrast), color temperature (white point), and color gamut size.

Standard RGB working spaces diagrammed in the CIE xyY system enable comparison with the color gamut of the human eye (black horseshoe).

Standard working spaces provide a common ground, or place to store image data until you know what you want to do with it.

When Photoshop 5 was introduced, a big hullabaloo ensued because the default standard RGB working space was sRGB (standard RGB). sRGB was introduced by HP and Microsoft to represent the "least common denominator" of home PCs. Many users felt that sRGB had too small a color gamut to represent CMYK printing on offset presses, much less more colorful large-format printers. At that time, many users favored the ColorMatch RGB profile that was introduced by Radius for its ColorMatch line of professional graphics monitors. ColorMatch RGB has a larger gamut than sRGB. Now most users prefer Adobe RGB, which has a very large gamut and can encompass the color gamut of most large-format printers.

For most work, however, you won't see a difference if you print an image from sRGB, ColorMatch RGB, or Adobe RGB.

Many image-capture devices, such as the HP Scanjet 8200 scanner, can capture images to a standard working space.

Workflow with Standard Working Spaces
The idea behind standard working spaces is to convert images captured from digital cameras or scanners, or work created on the computer (for example, in an illustration program) to a standard RGB working space. This workflow avoids possible confusion by keeping all images in the same working space. It also keeps you from having to convert images from multiple working spaces at the time of output.

Working with devices. Many input devices, including scanners and digital cameras, can capture images to standard RGB working spaces. Likewise, many output devices, including inkjet and electrostatic printers, are set up to receive RGB images in standard working spaces.

Photoshop's Print with Preview dialog box provides a way of applying an ICC profile to convert the image from standard working space to the printer profile.

If you have captured images using a custom scanner or camera profile, you may be able to convert them to a standard working space using your capture application or with a desktop application like Photoshop. Likewise, if you have a custom printer profile, you can convert to that profile in Photoshop or similar application before printing, or upon printing, images.

Photoshop's Save As dialog box enables the standard working space profile to be embedded with the image so that, when transferred from one computer to another the color will remain the same.

Embedding profiles. Standard working space profiles can be embedded into saved images, so that when the images are transferred from one computer to another, or from a content creator to a service provider, the color stays the same. Embedding the profile increases the file size slightly. If you have settled on a standard working space and capture, edit, and output color entirely in-house, you can save some disk space by not embedding the profiles. However, if anyone else might open your images with an application that can read profiles, embedding the profile ensures that they'll get the same color as the creator, so it's generally recommended.

Photoshop's Save As dialog box provides three options for handling files without an embedded profile. If you're given an image without a profile, you may have to try different standard profiles to see which looks best, but it's probably a good idea to show the customer a proof before going into production.

Missing profiles. If you open an image that has no embedded profile (Fig. 7), you can (1) ignore the missing profile, (2) assign the current working space, or (3) assign a selected profile. If you don't know what the image looked like when captured, your best bet is to assign a profile that makes the image look good. In production, of course, there is no guarantee that the profile you like is the one that the customer will like, so it's a good idea to show the customer a proof. If possible, contact the file's creator and find out the correct color space.