Although you can perform all color and tonal corrections in RGB mode and most adjustments in CMYK mode, you should choose a mode carefully. Avoid multiple conversions between modes, because color values are rounded and lost with each conversion. RGB images to be used on‑screen do not need to be converted to CMYK mode. CMYK images that will be separated and printed, do not need to have color corrections made in RGB mode.

If you must convert your image from one mode to another, perform most of your tonal and color corrections in RGB mode and use CMYK mode for fine-tuning. The advantages of working in RGB mode are:

• You can save memory and improve performance because there are fewer channels.

• RGB has a wider range of colors than CMYK, and more colors are likely to be preserved after adjustments.

  You can preview composite CMYK colors and separation plates using the CMYK working space in the Color Settings dialog box. Or, you can preview colors using a custom CMYK color profile.

  You can edit an image in RGB mode in one window and view the same image in CMYK colors in another window. Choose Window > Arrange > New Window For (Filename) to open a second window. Select the Working CMYK option for Proof Setup, then choose the Proof Color command to turn on the CMYK preview in one of the windows.