利用PIL生成水印图片或文字

//转载自：http://blog.struct.cn/2008/7/6/use-pil-create-watermark/

最近在做一个图片网站，要处理很多图片，处理图片少不了加水印了，呵呵。PIL用得不熟，在网上找了一圈，加上自己稍微修改了一下，用起来也算方便，生成效果也不错，呵呵，支持透明的png水印图片,透明度和水印位置都可以很方便的调整。

上几张测试图：








代码：

import Image, ImageEnhance POSITION = ('LEFTTOP','RIGHTTOP','CENTER','LEFTBOTTOM','RIGHTBOTTOM')PADDING = 10MARKIMAGE = '16.png' 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(imagefile, markfile, position=POSITION[4], opacity=1):    """Adds a watermark to an image."""       im = Image.open(imagefile)    mark = Image.open(markfile)       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 == 'title':        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))    elif position == POSITION[0]:        #lefttop        position = (PADDING,PADDING)        layer.paste(mark, position)    elif position == POSITION[1]:        #righttop        position = (im.size[0] - mark.size[0]-PADDING, PADDING)        layer.paste(mark, position)    elif position == POSITION[2]:        #center        position = ((im.size[0] - mark.size[0])/2,(im.size[1] - mark.size[1])/2)        layer.paste(mark, position)    elif position == POSITION[3]:        #left bottom        position = (PADDING,im.size[1] - mark.size[1]-PADDING,)        layer.paste(mark, position)    else:        #right bottom (default)        position = (im.size[0] - mark.size[0]-PADDING, im.size[1] - mark.size[1]-PADDING,)        layer.paste(mark, position)             # composite the watermark with the layer    return Image.composite(layer, im, layer) def test():    watermark('1.jpg',MARKIMAGE,POSITION[0],opacity=0.7).save("watermarked_lt.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,POSITION[1],opacity=0.7).save("watermarked_rt.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,POSITION[2],opacity=0.7).save("watermarked_center.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,POSITION[3],opacity=0.7).save("watermarked_lb.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,POSITION[4],opacity=0.7).save("watermarked_rb.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,'title',opacity=0.7).save("watermarked_title.jpg",quality=90)    watermark('1.jpg',MARKIMAGE,'scale',opacity=0.7).save("watermarked_scale.jpg",quality=90)if __name__ == '__main__':    test()