python使用PIL模块实现给图片打水印的方法


            本文实例讲述了python使用PIL模块实现给图片打水印的方法。分享给大家供大家参考。具体实现方法如下：





import Image, ImageEnhance

def reduce_opacity(im, opacity):

  """Returns an image with reduced opacity."""

  assert opacity >= 0 and opacity <= 1

  if im.mode != 'RGBA':

    im = im.convert('RGBA')

  else:

    im = im.copy()

  alpha = im.split()[3]

  alpha = ImageEnhance.Brightness(alpha).enhance(opacity)

  im.putalpha(alpha)

  return im

def watermark(im, mark, position, opacity=1):

  """Adds a watermark to an image."""

  if opacity < 1:

    mark = reduce_opacity(mark, opacity)

  if im.mode != 'RGBA':

    im = im.convert('RGBA')

  # create a transparent layer the size of the image and draw the

  # watermark in that layer.

  layer = Image.new('RGBA', im.size, (0,0,0,0))

  if position == 'tile':

    for y in range(0, im.size[1], mark.size[1]):

      for x in range(0, im.size[0], mark.size[0]):

        layer.paste(mark, (x, y))

  elif position == 'scale':

    # scale, but preserve the aspect ratio

    ratio = min(

      float(im.size[0]) / mark.size[0], float(im.size[1]) / mark.size[1])

    w = int(mark.size[0] * ratio)

    h = int(mark.size[1] * ratio)

    mark = mark.resize((w, h))

    layer.paste(mark, ((im.size[0] - w) / 2, (im.size[1] - h) / 2))

  else:

    layer.paste(mark, position)

  # composite the watermark with the layer

  return Image.composite(layer, im, layer)

def test():

  im = Image.open('test.png')

  mark = Image.open('overlay.png')

  watermark(im, mark, 'tile', 0.5).show()

  watermark(im, mark, 'scale', 1.0).show()

  watermark(im, mark, (100, 100), 0.5).show()

if __name__ == '__main__':

  test()



希望本文所述对大家的Python程序设计有所帮助。