image mode

参见
http://effbot.org/imagingbook/concepts.htm#mode

另：
本地保留查询页面
http://www.pythonware.com/library/pil/handbook/
http://effbot.org/zone/pil-index.htm

Mode #

The mode of an image defines the type and depth of a pixel in the image. The current release supports the following standard modes:

• 1 (1-bit pixels, black and white, stored with one pixel per byte)

• L (8-bit pixels, black and white)

• P (8-bit pixels, mapped to any other mode using a colour palette)

• RGB (3x8-bit pixels, true colour)

• RGBA (4x8-bit pixels, true colour with transparency mask)

• CMYK (4x8-bit pixels, colour separation)

• YCbCr (3x8-bit pixels, colour video format)

• I (32-bit signed integer pixels)

• F (32-bit floating point pixels)

PIL also provides limited support for a few special modes, including LA (L with alpha), RGBX (true colour with padding) and RGBa (true colour with premultiplied alpha). However, PIL doesn’t support user-defined modes; if you to handle band combinations that are not listed above, use a sequence of Image objects.

You can read the mode of an image through the mode attribute. This is a string containing one of the above values.