ABSTRACT
This chapter covers the color modes in Adobe Photoshop, tools and functions available to blend channels, and provides some exercises demonstrating the multiple strategies that can be successfully applied to a single image. Green filters were useful to enhance the purple tones of a fingerprint developed with ninhydrin, or an orange filter might be used to photograph a manila envelope to create contrast between the friction ridge detail and the substrate. RGB colors are additive colors, created by mixing spectral light in various intensities; monitors for example, create color by emitting light through red, green, and blue phosphors. CMYK colors are subtractive colors, and the information is separated into four channels: cyan, magenta, yellow, and black. Standard grayscale and color images use an 8-bit mode tonal range. The values of the blend channel are subtracted from the base channel. The channel mixer is another way of blending color channels within the same image using color channel sliders.
