python生成指定尺寸的缩略图

def MakeThumb(path,sizes=(75,32,16)):
    """
    缩略图生成程序 by Neil Chen
    sizes 参数传递要生成的尺寸，可以生成多种尺寸
    """
    base,ext = os.path.splitext(path)
    try:
        im = Image.open(path)
    except IOError:
        return
    mode = im.mode
    if mode not in ('L','RGB'):
        if mode == 'RGBA':
            # 透明图片需要加白色底
            alpha = im.split()[3]
            bgmask = alpha.point(lambda x: 255-x)
            im = im.convert('RGB')
            # paste(color,box,mask)
            im.paste((255,255,255),None,bgmask)
        else:
            im = im.convert('RGB')
 
    width,height = im.size
    if width == height:
        region = im
    else:
        if width > height:
            delta = (width - height)/2
            box = (delta,delta+height,height)
        else:
            delta = (height - width)/2
            box = (0,delta,width,delta+width)
        region = im.crop(box)
 
    for size in sizes:
        filename = base + "_" + "%sx%s" % (str(size),str(size)) + ".jpg"
        thumb = region.resize((size,size),Image.ANTIALIAS)
        thumb.save(filename,quality=100) # 默认 JPEG 保存质量是 75,不太清楚。可选值(0~100)