Image or color mode defines how colors combine depending on the channel number in the color mode. Multiple color modes offer detail and file sizes of different color levels. In Photoshop, there are 5 types of color modes 1. RGB mode (millions of colors) 2. CMYK mode (four-printed colors) 3. Index mode (256 colors) 4. Grayscale mode (256 grays) 5. Bitmap mode (2 colors)