Modify the color balance: 第 5.2 节 “Color Balance”

Adjust hue, saturation and lightness levels: 第 5.3 节 “Hue-Saturation”

Render into a greyscale image seen through a colored glass: 第 5.4 节 “Colorize”

Adjust brightness and contrast levels: 第 5.5 节 “Brightness-Contrast”

Transform into a black and white image depending on pixel value: 第 5.6 节 “Threshold”

Change the intensity range in a channel: 第 5.7 节 “Levels”

Change color, brightness, contrast or transparency in a sophisticated way: 第 5.8 节 “Curves”

Reduce the number of colors: 第 5.9 节 “Posterize”

Convert all colors to corresponding shades of gray: 第 5.10 节 “Desaturate”