python3 pillow使用测试

# -*- encoding=utf-8 -*-
'''''
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img.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))
    img.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))  # 我这里有一层白色的膜，去掉(255,255,255) 这个参数就好了

    FONT = "simhei.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('img.jpg')  # image 对象
    compress_image(im)

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

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

    im = Image.open('img.jpg')  # image 对象
    text_watermark(im, 'arthas')

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

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