Predicting final display in the Save for Web dialog box (Photoshop)
- Uncompensated Color preview makes no adjustments to image gamma. Uncompensated Color is the default setting.
- Standard Windows Color displays an adjustment based on the default Windows gamma.
- Standard Macintosh Color displays an adjustment based on the default Macintosh gamma.
- Use Document Color Profile will adjust the gamma to match any attached document color profile in a color managed document. (For more information about document color profiles, see Embedding a profile in a document and Changing the color profile of a document.)
You can set the Save for Web dialog box to approximate color dithering and gamma in the viewer's Web browser and monitor.
Previewing browser dither
If an image contains more colors than the monitor can display, the browser will dither, or approximate, the colors that it cannot display by blending colors that it can.
To show or hide preview of browser dither, choose Browser Dither from the Preview pop-up menu 
. A check mark indicates that browser dithering is active. Activating Browser Dither will not affect final image output.
Previewing gamma shifts
The default gamma, or the brightness of midtone values produced by a display device, varies between operating systems. A graphic that appears properly on a Mac OS system may appear much darker on a Windows OS system. (See Adjusting color display for cross-platform variations and Adjusting the gamma value of an image (ImageReady) for cross-platform color discussions.)
To preview the shifts in gamma within the Save For Web dialog box, choose one of the options below from the Preview pop-up menu. (A check mark indicates that option is active. Activating a preview option will not affect final image output.)