Adobe Photoshop CS5 for Photographers - Martin Evening [283]
If the person you are supplying the file to is in the same building or you are in regular contact with them, then you probably have a clear idea of how their system is set up. If they have Photoshop color management switched on, they can read any file you send them in any color space and it will be color managed successfully. However, you cannot always make too many assumptions about who you are sending image files to and it is for this reason that you should sometimes adopt a more cautious approach. I am often asked to supply RGB files as large JPEGs for initial approval by the client before making a finished print. In these situations I find it safer to supply a profiled sRGB image. I do this by choosing Edit Convert to Profile… and select sRGB as the destination space. If the recipient is color management savvy, then the version of Photoshop they are working with should be able to read the sRGB profile and handle the colors correctly. If the recipient has not bothered to configure their color management settings then one can be almost certain that they are using sRGB as their default RGB workspace. So in these instances, converting to sRGB means they stand a better chance of seeing the colors correctly regardless of whether they have the color management on or off.
Figure 12.30 shows a comparison of how a photo that was edited using different RGB workspaces would look on a Photoshop system configured using a Color Management ‘Off’ setting and where the person receiving the file ignores the embedded profile. If the photo was delivered as an Adobe RGB file, the gamma would match, but because Adobe RGB has a larger gamut than sRGB the colors would appear slightly desaturated. If supplied as a ColorMatch RGB file, sRGB would interpret this as a darker image because ColorMatch has a lower gamma of 1.8. If supplied using ProPhoto RGB, the colors would appear even more muted when brought into sRGB without any color management. This is because ProPhoto RGB has a much larger color gamut. The bottom right example shows how the photo would look if the supplied image was in sRGB and opened in Photoshop with color management switched off, but with sRGB as the default RGB workspace. In this instance this is the most correct version. Of course, I am certainly not advocating you use sRGB as your standard RGB workspace, because it is still a poor space to use for photographic work, but it can be a useful ‘dumbed down’ space to convert to when communicating with unknown users.
Figure 12.30 The purpose of this illustration is to show what happens if you submit an RGB file originating in different RGB spaces to a Photoshop user who has their Photoshop system configured using sRGB as their RGB workspace and with the color management policies set to ‘Off’ (ignoring incoming profiles).
Matching grayscale gamma
If you are using the Epson Advanced B&W options to print grayscale images, it is best to make sure that the Gray working space matches the gamma of the RGB working space. If this is the case, use the following Gray gamma settings:
Colormatch RGB: 1.8 gamma
Adobe RGB: 2.2 gamma
sRGB: 2.2 gamma
ProPhoto RGB: 1.8 gamma
Grayscale for screen display
If you intend creating grayscale images to be seen on the Internet or in multimedia presentations, I suggest you choose the ‘Default Web Graphics’ color setting. The Grayscale workspace will then be set to a 2.2 gamma space, which is the same gamma that's used by the majority of PC and Mac computer displays. The truth is, you can never be 100% sure how anybody who views your work will have their display calibrated, but you can at least assume that the majority of Internet users will have a display set to a 2.2 gamma. The Macintosh 1.8 gamma setting should really be relegated to ancient history. The reason it exists at all is because in the very early days