图片处理代码

models.py

# -*- encoding=utf-8 -*-
import os
from time import time
from tempfile import NamedTemporaryFile
try:
    from PIL import Image
except ImportError:
    import Image

from settings import MEDIA_ROOT
from django.db import models
from django.core.files import File
from django.contrib.auth.models import User

'''
对图片进行处理之后再保存的原始方法，集成在django中
'''

def generate_food(instance, filename):
    ext = filename.split('.')[-1]
    nname = str(int(time())) + '.' + ext
    return os.path.join("food", nname)


class Activity(models.Model):
    user = models.ForeignKey(User)
    content = models.CharField(max_length=40, default='')

    def __unicode__(self):
        return self.content

class Food(models.Model):
    user = models.ForeignKey(User)
    name = models.CharField(max_length=20, default='')
    image = models.ImageField(max_length=255, default='', upload_to=generate_food)
    small = models.ImageField(max_length=255, default='', upload_to="food")  #small 为空的时候报错！！
    price = models.IntegerField()
    discount = models.IntegerField()
    note = models.CharField(max_length=50, default='')

    def __unicode__(self):
        return self.name

    def save(self, *args, **kwargs):
        #windows 下会有问题，linxu可以正常运行

        super(Food, self).save(*args, **kwargs)
        im = Image.open(os.path.join(MEDIA_ROOT, self.image.name))
        self.width, self.height = im.size


        #im.thumbnail((200,100), Image.ANTIALIAS)    #这种方式质量损坏很大
        fn, ext = os.path.splitext(self.image.name)
        x, y, w, h = resize_image(self.width, self.height)
        box = (x,y,w+x,h+y)
        ratio = float(300) / w
        newWidth = int(w * ratio)
        newHeight = int(h * ratio)

        newIm = im.crop(box)
        im = None
        #newIm.resize((newWidth,newHeight),Image.ANTIALIAS)  #压缩图片
        print box
        print self.width, self.height

        simage_name = fn + "-s" + ext
        tf = NamedTemporaryFile(delete=True)
        newIm.save(tf.name, "JPEG", quality=95)
        self.small.save(simage_name, File(open(tf.name)), save=False)
        tf.close()
        super(Food, self).save(*args, **kwargs)


def resize_image(ori_w, ori_h, dst_w=200, dst_h=100):
    '''
    计算裁剪尺度
    '''
    dst_scale = float(dst_h) / 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*(1/dst_scale))

        x = (ori_w - width) / 2
        y = 0
    return x,y,width,height

pil_learn.py

# -*- encoding=utf-8 -*-
'''
author: orangleliu
pil处理图片，验证，处理
大小，格式 过滤
压缩，截图，转换

图片库最好用Pillow
还有一个测试图片test.jpg, 一个log图片，一个字体文件
'''

#图片的基本参数获取
try:
    from PIL import Image, ImageDraw, ImageFont, ImageEnhance
except ImportError:
    import Image, ImageDraw, ImageFont, ImageEnhance

def compress_image(img, w=128, h=128):
    '''
    缩略图
    '''
    img.thumbnail((w,h))
    im.save('test1.png', 'PNG')
    print u'成功保存为png格式, 压缩为128*128格式图片'

def cut_image(img):
    '''
    截图, 旋转，再粘贴
    '''
    #eft, upper, right, lower
    #x y z w  x,y 是起点， z,w是偏移值
    width, height = img.size
    box = (width-200, height-100, width, height)
    region = img.crop(box)
    #旋转角度
    region = region.transpose(Image.ROTATE_180)
    img.paste(region, box)
    img.save('test2.jpg', 'JPEG')
    print u'重新拼图成功'

def logo_watermark(img, logo_path):
    '''
    添加一个图片水印,原理就是合并图层，用png比较好
    '''
    baseim = img
    logoim = Image.open(logo_path)
    bw, bh = baseim.size
    lw, lh = logoim.size
    baseim.paste(logoim, (bw-lw, bh-lh))
    baseim.save('test3.jpg', 'JPEG')
    print u'logo水印组合成功'

def text_watermark(img, text, out_file="test4.jpg", angle=23, opacity=0.50):
    '''
    添加一个文字水印，做成透明水印的模样，应该是png图层合并
    http://www.pythoncentral.io/watermark-images-python-2x/
    这里会产生著名的 ImportError("The _imagingft C module is not installed") 错误
    Pillow通过安装来解决 pip install Pillow
    '''
    watermark = Image.new('RGBA', img.size, (255,255,255))
    FONT = "msyh.ttf"
    size = 2

    n_font = ImageFont.truetype(FONT, size)                                       #得到字体
    n_width, n_height = n_font.getsize(text)
    text_box = min(watermark.size[0], watermark.size[1])
    while (n_width+n_height <  text_box):
        size += 2
        n_font = ImageFont.truetype(FONT, size=size)
        n_width, n_height = n_font.getsize(text)                                   #文字逐渐放大，但是要小于图片的宽高最小值

    text_width = (watermark.size[0] - n_width) / 2
    text_height = (watermark.size[1] - n_height) / 2
    #watermark = watermark.resize((text_width,text_height), Image.ANTIALIAS)
    draw = ImageDraw.Draw(watermark, 'RGBA')                                       #在水印层加画笔
    draw.text((text_width,text_height),
              text, font=n_font, fill="#21ACDA")
    watermark = watermark.rotate(angle, Image.BICUBIC)
    alpha = watermark.split()[3]
    alpha = ImageEnhance.Brightness(alpha).enhance(opacity)
    watermark.putalpha(alpha)
    Image.composite(watermark, img, watermark).save(out_file, 'JPEG')
    print u"文字水印成功"


#等比例压缩图片
def resizeImg(img, dst_w=0, dst_h=0, qua=85):
    '''
    只给了宽或者高，或者两个都给了，然后取比例合适的
    如果图片比给要压缩的尺寸都要小，就不压缩了
    '''
    ori_w, ori_h = im.size
    widthRatio = heightRatio = None
    ratio = 1

    if (ori_w and ori_w > dst_w) or (ori_h and ori_h  > dst_h):
        if dst_w and ori_w > dst_w:
            widthRatio = float(dst_w) / ori_w                                      #正确获取小数的方式
        if dst_h and ori_h > dst_h:
            heightRatio = float(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("test5.jpg", "JPEG", quality=qua)
    print u'等比压缩完成'

    '''
    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(im, dst_w, dst_h, qua=95):
    '''
        先按照一个比例对图片剪裁，然后在压缩到指定尺寸
        一个图片 16:5 ，压缩为 2:1 并且宽为200，就要先把图片裁剪成 10:5,然后在等比压缩
    '''
    ori_w,ori_h = im.size

    dst_scale = float(dst_w) / dst_h  #目标高宽比
    ori_scale = float(ori_w) / ori_h #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) / 2

    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(dst_w) / width
    newWidth = int(width * ratio)
    newHeight = int(height * ratio)
    newIm.resize((newWidth,newHeight),Image.ANTIALIAS).save("test6.jpg", "JPEG",quality=95)
    print  "old size  %s  %s"%(ori_w, ori_h)
    print  "new size %s %s"%(newWidth, newHeight)
    print u"剪裁后等比压缩完成"


if __name__ == "__main__":
    '''
    主要是实现功能， 代码没怎么整理
    '''
    im = Image.open('test.jpg')  #image 对象
    compress_image(im)

    im = Image.open('test.jpg')  #image 对象
    cut_image(im)

    im = Image.open('test.jpg')  #image 对象
    logo_watermark(im, 'logo.png')

    im = Image.open('test.jpg')  #image 对象
    text_watermark(im, 'Orangleliu')

    im = Image.open('test.jpg')  #image 对象
    resizeImg(im, dst_w=100, qua=85)

    im = Image.open('test.jpg')  #image 对象
    clipResizeImg(im, 100, 200)