python(PIL)图像处理(等比例压缩、裁剪压缩) 缩略(水印)图

#coding:utf-8
'''
    python图片处理
    @author:fc_lamp
    @blog:http://fc-lamp.blog.163.com/
'''
import Image as image

#等比例压缩图片
def resizeImg(**args):
    args_key = {'ori_img':'','dst_img':'','dst_w':'','dst_h':'','save_q':75}
    arg = {}
    for key in args_key:
        if key in args:
            arg[key] = args[key]
        
    im = image.open(arg['ori_img'])
    ori_w,ori_h = im.size
    widthRatio = heightRatio = None
    ratio = 1
    if (ori_w and ori_w > arg['dst_w']) or (ori_h and ori_h > arg['dst_h']):
        if arg['dst_w'] and ori_w > arg['dst_w']:
            widthRatio = float(arg['dst_w']) / ori_w #正确获取小数的方式
        if arg['dst_h'] and ori_h > arg['dst_h']:
            heightRatio = float(arg['dst_h']) / ori_h

        if widthRatio and heightRatio:
            if widthRatio < heightRatio:
                ratio = widthRatio
            else:
                ratio = heightRatio

        if widthRatio and not heightRatio:
            ratio = widthRatio
        if heightRatio and not widthRatio:
            ratio = heightRatio
            
        newWidth = int(ori_w * ratio)
        newHeight = int(ori_h * ratio)
    else:
        newWidth = ori_w
        newHeight = ori_h
        
    im.resize((newWidth,newHeight),image.ANTIALIAS).save(arg['dst_img'],quality=arg['save_q'])

    '''
    image.ANTIALIAS还有如下值：
    NEAREST: use nearest neighbour
    BILINEAR: linear interpolation in a 2x2 environment
    BICUBIC:cubic spline interpolation in a 4x4 environment
    ANTIALIAS:best down-sizing filter
    '''

#裁剪压缩图片
def clipResizeImg(**args):
    
    args_key = {'ori_img':'',ori_h = im.size

    dst_scale = float(arg['dst_h']) / arg['dst_w'] #目标高宽比
    ori_scale = float(ori_h) / ori_w #原高宽比

    if ori_scale >= dst_scale:
        #过高
        width = ori_w
        height = int(width*dst_scale)

        x = 0
        y = (ori_h - height) / 3
        
    else:
        #过宽
        height = ori_h
        width = int(height*dst_scale)

        x = (ori_w - width) / 2
        y = 0

    #裁剪
    box = (x,y,width+x,height+y)
    #这里的参数可以这么认为：从某图的(x,y)坐标开始截，截到(width+x,height+y)坐标
    #所包围的图像，crop方法与php中的imagecopy方法大为不一样
    newIm = im.crop(box)
    im = None

    #压缩
    ratio = float(arg['dst_w']) / width
    newWidth = int(width * ratio)
    newHeight = int(height * ratio)
    newIm.resize((newWidth,quality=arg['save_q'])
    

#水印(这里仅为图片水印)
def waterMark(**args):
    args_key = {'ori_img':'','mark_img':'','water_opt':''}
    arg = {}
    for key in args_key:
        if key in args:
            arg[key] = args[key]
        
    im = image.open(arg['ori_img'])
    ori_w,ori_h = im.size

    mark_im = image.open(arg['mark_img'])
    mark_w,mark_h = mark_im.size
    option ={'leftup':(0,0),'rightup':(ori_w-mark_w,'leftlow':(0,ori_h-mark_h),'rightlow':(ori_w-mark_w,ori_h-mark_h)
             }
    

    im.paste(mark_im,option[arg['water_opt']],mark_im.convert('RGBA'))
    im.save(arg['dst_img'])
    

        
#Demon
#源图片
ori_img = 'D:/tt.jpg'
#水印标
mark_img = 'D:/mark.png'
#水印位置(右下)
water_opt = 'rightlow'
#目标图片
dst_img = 'D:/python_2.jpg'
#目标图片大小
dst_w = 94
dst_h = 94
#保存的图片质量
save_q = 35
#裁剪压缩
clipResizeImg(ori_img=ori_img,dst_img=dst_img,dst_w=dst_w,dst_h=dst_h,save_q = save_q)
#等比例压缩
#resizeImg(ori_img=ori_img,save_q=save_q)
#水印
#waterMark(ori_img=ori_img,mark_img=mark_img,water_opt=water_opt)