iIndex

The index into the array of grayscale bitmaps that are the color separations. The separations follow the color order of the image data. In most cases, this is the same as the abbreviation of the color-plane model. For example, in a CMYK separation, ColorPlanes(0) is the cyan plane. The only exception is RGB, where the image data is usually stored as blue-green-red, and ColorPlanes(0) is the blue plane.