本文实例讲述了Python图像处理之gif动态图的解析与合成操作。分享给大家供大家参考，具体如下：

gif动态图是在现在已经司空见惯，朋友圈里也经常是一言不合就斗图。这里，就介绍下如何使用python来解析和生成gif图像。

一、gif动态图的合成

如下图，是一个gif动态图。

gif动态图的解析可以使用PIL图像模块即可，具体代码如下：

#-*- coding: UTF-8 -*-
import os
from PIL import Image
def analyseImage(path):
 '''
 Pre-process pass over the image to determine the mode (full or additive).
 Necessary as assessing single frames isn't reliable. Need to know the mode
 before processing all frames.
 '''
 im = Image.open(path)
 results = {
 'size': im.size,
 'mode': 'full',
 }
 try:
 while True:
 if im.tile:
 tile = im.tile[0]
 update_region = tile[1]
 update_region_dimensions = update_region[2:]
 if update_region_dimensions != im.size:
 results['mode'] = 'partial'
 break
 im.seek(im.tell() + 1)
 except EOFError:
 pass
 return results
def processImage(path):
 '''
 Iterate the GIF, extracting each frame.
 '''
 mode = analyseImage(path)['mode']
 im = Image.open(path)
 i = 0
 p = im.getpalette()
 last_frame = im.convert('RGBA')
 try:
 while True:
 print "saving %s (%s) frame %d, %s %s" % (path, mode, i, im.size, im.tile)
 '''
 If the GIF uses local colour tables, each frame will have its own palette.
 If not, we need to apply the global palette to the new frame.
 '''
 if not im.getpalette():
 im.putpalette(p)
 new_frame = Image.new('RGBA', im.size)
 '''
 Is this file a "partial"-mode GIF where frames update a region of a different size to the entire image?
 If so, we need to construct the new frame by pasting it on top of the preceding frames.
 '''
 if mode == 'partial':
 new_frame.paste(last_frame)
 new_frame.paste(im, (0,0), im.convert('RGBA'))
 new_frame.save('%s-%d.png' % (''.join(os.path.basename(path).split('.')[:-1]), i), 'PNG')
 i += 1
 last_frame = new_frame
 im.seek(im.tell() + 1)
 except EOFError:
 pass
def main():
 processImage('test_gif.gif')
if __name__ == "__main__":
 main()

解析结果如下，由此可见改动态图实际上是由14张相同分辨率的静态图组合而成

二、gif动态图的合成

gif图像的合成，使用imageio库（https://pypi.python.org/pypi/imageio）

代码如下：

#-*- coding: UTF-8 -*-
import imageio
def create_gif(image_list, gif_name):
 frames = []
 for image_name in image_list:
 frames.append(imageio.imread(image_name))
 # Save them as frames into a gif
 imageio.mimsave(gif_name, frames, 'GIF', duration = 0.1)
 return
def main():
 image_list = ['test_gif-0.png', 'test_gif-2.png', 'test_gif-4.png',
 'test_gif-6.png', 'test_gif-8.png', 'test_gif-10.png']
 gif_name = 'created_gif.gif'
 create_gif(image_list, gif_name)
if __name__ == "__main__":
 main()

这里，使用第一步解析出来的图像中的8幅图，间副的间隔时间为0.1s，合成新的gif动态图如下：