The Color Type option is used when user wants to save an image without colors. Grayscale pictures have smaller size and higher load speed.
Use the Color Depth to set the pixel format of the JPEG image to 8-bit for video drivers that cannot display 24-bit. The native format of a JPEG image is 24-bit.
Use the Quality to set the compression quality of the JPEG image. Higher compression results in a poorer picture quality, but a smaller file size.
Set the Progressive option on to compress an image, so that it can be progressively displayed when it is decompressed.