Indexed Color mode uses a small color palette to create a file that looks good onscreen and has a significantly smaller file size . Therefore, any onscreen images (used in PowerPoint presentations or multimedia, for example) look good in this mode. However, indexed color does not print well and restricts many Photoshop operations, so in general, keep a copy of your file in RGB mode and create a copy that is in Indexed Color mode. Make sure all operations such as filters are done before changing to indexed color.
Q2:
What is Lab color?
A2:
Lab color is a mode that is used by Photoshop to aid in the conversion between color modes. It is used for specific purposes, such as sharpening, or to convert a color file into a grayscale image.
Q3:
When should I use RGB mode versus CMYK mode?
A3:
In general, CMYK mode is used when printing to a printing press in full color (Cyan Magenta Yellow Black is also referred to as process color or four-color printing). RGB is typically used when capturing images from scanners and digital cameras , and is also used for monitor output such as video, multimedia, presentations, and the Web. Typically, people tend to work in RGB mode because it creates smaller file sizes, plus all Photoshop operations work in RGB mode. Toward the end of a project, you might convert an image to CMYK for printing or to some other mode (such as Indexed Color) for onscreen presentations.
Q4:
Is it possible to view CMYK when working in RGB? I am working in RGB mode, but I'd like to get an idea of what my image will look like in CMYK. Do I have to change the mode?
A4:
There is a way to "preview" a good approximation of what your image will look like in CMYK. From the View menu, choose Proof Setup and make sure that Working CMYK is selected. Then choose Proof Colors or press Command-Y (PC: Control-Y).
