pythonpil安装包
基于Python的PIL库学习详解摘要
对于图像识别,大量的工作在于图像的处理,处理效果好,那么才能很好地识别,因此,良好的图像处理是识别的基础。在python中,有一个优秀的图像处理框架,就是pil库,本博文会分模块,介绍pil库中的各种方法,并列举相关例子。
参考:http://pillow-cn.readthedocs.io/zh_cn/latest/reference/index.html
网站上列举了pil库中所有的模块和方法,但是没有相关的例子,博文中会尽量给出相关的例子和进行简单的讲解。
基于的环境:win10,python2.7,pil 1.1.7。
image模块
开篇的例子
首先,给出image模块中的一个简单的例子。例子实现的功能是:读取图片,并进行45°旋转,然后进行可视化。
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# -*- coding:utf-8 -*- # image模块开篇例子 from pil import image im = image. open ( 'test.bmp' ) # 读取图片 im.rotate( 45 ).show() # 将图片旋转,并用系统自带的图片工具显示图片 |
创建缩略图
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# -*- coding:utf-8 -*- # pil中创建缩略图(create thumbnails) from pil import image import glob,os size = 128 , 128 for infile in glob.glob( "*.jpg" ): # glob的作用是文件搜索,返回的是一个列表 file ,ext = os.path.splitext(infile) # 将文件的文件名和拓展名分开,用于之后的保存重命名 im = image. open (infile) im.thumbnail(size,image.antialias) # 等比例缩放 im.save( file + ".thumbnail" , "jpeg" ) #im.show() # 显示缩略图 #print im.size,im.mode |
缩略图不能直接双击打开,而可以使用pil.image的open读取,然后使用show()方法进行显示。
图像处理
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pil.image.alpha_composite(im1,im2) pil.image.blend(im1,im2,alpha) pil.image.composite(im1,im2,mask) |
这三个方法都属于图片的合成或者融合。都要求im1和im2的mode和size要一致,alpha代表图片占比的意思,而mask是mode可以为”1”,”l”或者”rgba”的size和im1、im2一致的。
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# coding:utf-8 -*- from pil import image # 图片合成 # pil的alpha_composite(im1,im2) 图像通道融合 # im2要和im1的size和mode一致,且要求格式为rgba im1 = image. open ( "test.png" ) im2 = image. open ( "test2.png" ) newim1 = image.alpha_composite(im1,im2) # 将im2合成到im1中,如果其一是透明的, # 才能看到结果,不然最终结果只会显示出im2 newim1.show() #print(im1.mode) # ----------------------------------------- # image.blend(im1,im2,alpha) # alpha为透明度 newim2 = image.blend(im1,im2, 0.5 ) newim2.show() # ----------------------------------------- mask = image. open ( "mask.png" ) newim3 = image.composite(im2,im1,mask) newim3.show() |
pil.image.eval(image,*args)
程序:
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# -*- coding:utf-8 -*- from pil import image im = image. open ( "test.png" ) imnew = image. eval (im, lambda i:i * 2 ) # 将原图片的像素点,都乘2,返回的是一个image对象 #print imnew.mode imnew.show() im.show() |
创建图像
(1) pil.image.new(mode,size,color=0)
使用模式和大小,创建一个新的图像。其中,mode可以是”l”,”rgb”,”rgba”;而size则是一个tuple(元组),color应该和mode相对应。
下面例子,分别创建”l”、”rgb”和”rgba”的图片。
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# -*- coding:utf-8 -*- from pil import image # 创建图像 # 创建一个灰度图像 newl = image.new( "l" ,( 28 , 28 ), 255 ) newl.show() # 创建一个rgb图像 newrgb = image.new( "rgb" ,( 28 , 28 ),( 20 , 200 , 45 )) newrgb.show() newrgba = image.new( "rgba" ,( 28 , 28 ),( 20 , 200 , 45 , 255 )) newrgba.show() print "the frist image:" ,newl.size,newl.mode print "the second image:" ,newrgb.size,newrgb.mode print "the third image:" ,newrgba.size,newrgba.mode |
(2)以其他形式创建图像
a. 以数组的形式创建图像,pil.image.fromarray(obj,mode=none)
obj - 图像的数组,类型可以是numpy.array()
mode - 如果不给出,会自动判断
本人觉得这个功能还是挺实用的,可以将一个数组(具体一点就是像素数组)转换为图像,从图像的本质去处理图像。
下面一段程序,就是用fromarray()函数实现图像的灰度化(使用了两种方法)。
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# -*- coding:utf-8 -*- from pil import image import numpy as np a = image. open ( "fromimg.png" ) a.show() b = a.resize(( 28 , 28 )) datab = list (b.getdata()) #print type(datab) obj1 = [] obj2 = [] for i in range ( len (datab)): obj1.append([ sum (datab[i]) / 3 ]) # 灰度化方法1:rgb三个分量的均值 obj2.append([ 0.3 * datab[i][ 0 ] + 0.59 * datab[i][ 1 ] + 0.11 * datab[i][ 2 ]]) #灰度化方法2:根据亮度与rgb三个分量的对应关系:y=0.3*r+0.59*g+0.11*b obj1 = np.array(obj1).reshape(( 28 , 28 )) obj2 = np.array(obj2).reshape(( 28 , 28 )) print obj1 print obj2 arrayimg1 = image.fromarray(obj1) arrayimg2 = image.fromarray(obj2) arrayimg1.show() arrayimg2.show() |
显然,两种方法都能成功灰度化。
还有:
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pil.image.frombytes(mode,size,data,decoder_name = 'raw' , * args) pil.image.fromstring( * args, * * kw) pil.image.frombuffer(mode,size,data,decoder_name = 'raw' , * args) |
感觉不常用,没有仔细研究。
image模块下的image类
下面的image是一个图像对象,而不是模块!
(1) image.convert(mode=none,matrix=none,dither=none,palette=0,color=256)
该方法,同样可以实现上面的灰度化处理。
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# -*- coding:utf-8 -*- from pil import image img = image. open ( "test.png" ) # 灰度化:将rgb/rgba -> l img = img.convert( "l" ) img.show() |
(2) image.copy()
将读取的图片复制一份。
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# -*- coding:utf-8 -*- from pil import image img = image. open ( "test.png" ) # 灰度化:将rgb/rgba -> l img = img.convert( "l" ) #img.show() # ------ copy()---------- img1 = img.copy() img1.show() |
将灰度化的图片复制一份,因此该程序的运行结果和之前的一致。
(3) image.filter(filter)
该函数是用于图像滤波的,pil中自带了很多的滤波器,就是括号中的filter的参数。filter应该是一个imaagefilter模块下的对象。这里把imagefilter模块讲了。其实,该模块就是提供滤波器。自带的滤波器有:
使用中值滤波:
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# -*- coding:utf-8 -*- from pil import image from pil import imagefilter # blur - 模糊处理 # contour - 轮廓处理 # detail - 增强 # edge_enhance - 将图像的边缘描绘得更清楚 # edge_enhance_nore - 程度比edge_enhance更强 # emboss - 产生浮雕效果 # smooth - 效果与edge_enhance相反,将轮廓柔和 # smooth_more - 更柔和 # sharpen - 效果有点像detail testimg = image. open ( "filter1.png" ) testimg.show() filterimg = testimg. filter (imagefilter.medianfilter) filterimg.show() |
(4) 使用各种方法/函数获取图片的基本信息
image.getbands()
image.geebbox()
image.getcolors(maxcolor=256)
image.getdata(band=none)(一般和list()结合使用)
image.getextrema()
image.getpixel((x,y))
image.histogram(mask=none,extrema=none)
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# -*- coding:utf-8 -*- from pil import image img1 = image. open ( "test.png" ) img1.show() # getbands() - 显示该图像的所有通道,返回一个tuple bands = img1.getbands() print bands # getbbox() - 返回一个像素坐标,4个元素的tuple bboxs = img1.getbbox() print bboxs # getcolors() - 返回像素信息,是一个含有元素的列表[(该种像素的数量,(该种像素)),(...),...] colors = img1.getcolors() print colors # getdata() - 返回图片所有的像素值,要使用list()才能显示出具体数值 #data = list(img1.getdata()) #print data # getextrema() - 获取图像中每个通道的像素最小和最大值,是一个tuple类型 extremas = img1.getextrema() print extremas # getpixel() - 获取该坐标 pixels = img1.getpixel(( 87 , 180 )) print pixels # histogram() - 返回图片的像素直方图 print (img1.histogram()) |
运行结果:
('r', 'g', 'b', 'a')
(0, 0, 338, 238)
[(73463, (255, 255, 255, 255)), (32, (252, 249, 252, 255)), (1, (255, 189, 143, 255)), (12, (255, 199, 160, 255)), (22, (247, 239, 247, 255)), (3, (255, 242, 246, 255)), (9, (238, 221, 238, 255)), (9, (235, 215, 235, 255)), (5, (232, 209, 232, 255)), (1, (255, 228, 209, 255)), (2, (255, 210, 225, 255)), (1, (255, 202, 201, 255)), (3, (255, 158, 92, 255)), (22, (218, 181, 218, 255)), (1, (217, 181, 218, 255)), (2, (255, 232, 217, 255)), (16, (255, 195, 153, 255)), (22, (212, 169, 212, 255)), (3, (211, 169, 212, 255)), (1, (204, 153, 204, 255)), (1, (255, 229, 238, 255)), (53, (255, 131, 46, 255)), (9, (255, 203, 167, 255)), (1, (255, 157, 90, 255)), (3, (186, 119, 187, 255)), (2, (255, 217, 229, 255)), (6, (183, 113, 184, 255)), (1, (255, 212, 227, 255)), (14, (214, 175, 215, 255)), (2, (255, 182, 131, 255)), (12, (166, 79, 167, 255)), (2, (255, 180, 127, 255)), (4309, (255, 127, 39, 255)), (737, (163, 73, 164, 255)), (4, (255, 252, 253, 255)), (3, (255, 232, 216, 255)), (9, (255, 250, 233, 255)), (1, (255, 245, 248, 255)), (34, (255, 239, 228, 255)), (3, (255, 142, 64, 255)), (1, (255, 162, 98, 255)), (19, (255, 247, 241, 255)), (7, (255, 223, 201, 255)), (2, (255, 133, 49, 255)), (16, (255, 221, 232, 255)), (58, (255, 235, 221, 255)), (1, (255, 225, 204, 255)), (2, (255, 219, 194, 255)), (21, (255, 175, 120, 255)), (6, (255, 182, 206, 255)), (37, (255, 243, 235, 255)), (3, (255, 179, 127, 255)), (6, (255, 207, 223, 255)), (3, (255, 232, 240, 255)), (1, (255, 134, 51, 255)), (2, (255, 222, 233, 255)), (2, (255, 218, 192, 255)), (1, (255, 186, 186, 255)), (1, (255, 163, 99, 255)), (1, (255, 207, 173, 255)), (8, (255, 151, 80, 255)), (1, (255, 184, 201, 255)), (19, (255, 211, 180, 255)), (1, (255, 143, 65, 255)), (9, (255, 233, 158, 255)), (18, (255, 215, 187, 255)), (1, (255, 185, 136, 255)), (7, (255, 227, 237, 255)), (22, (255, 163, 100, 255)), (1, (255, 221, 198, 255)), (5, (255, 184, 208, 255)), (10, (255, 195, 215, 255)), (5, (255, 239, 182, 255)), (1, (255, 197, 157, 255)), (1, (255, 154, 85, 255)), (1, (255, 136, 55, 255)), (8, (255, 240, 190, 255)), (14, (255, 216, 229, 255)), (3, (255, 179, 204, 255)), (1, (255, 143, 67, 255)), (1, (255, 196, 155, 255)), (19, (255, 249, 227, 255)), (2, (255, 211, 181, 255)), (10, (255, 230, 142, 255)), (4, (255, 187, 140, 255)), (195, (255, 201, 14, 255)), (2, (255, 129, 42, 255)), (1, (255, 131, 47, 255)), (12, (255, 231, 214, 255)), (1, (255, 181, 151, 255)), (8, (249, 244, 249, 255)), (13, (246, 238, 246, 255)), (44, (244, 234, 244, 255)), (1, (243, 232, 244, 255)), (7, (240, 226, 241, 255)), (25, (255, 167, 107, 255)), (24, (255, 215, 229, 255)), (22, (230, 206, 230, 255)), (6, (229, 204, 229, 255)), (3, (255, 130, 45, 255)), (11, (227, 200, 228, 255)), (4, (226, 198, 226, 255)), (3, (255, 127, 40, 255)), (5, (223, 192, 223, 255)), (9, (220, 186, 221, 255)), (172, (255, 174, 201, 255)), (16, (255, 231, 239, 255)), (1, (255, 171, 113, 255)), (33, (209, 164, 209, 255)), (1, (255, 192, 213, 255)), (6, (255, 247, 250, 255)), (2, (255, 136, 54, 255)), (9, (255, 253, 247, 255)), (1, (255, 171, 114, 255)), (2, (255, 147, 73, 255)), (5, (255, 181, 130, 255)), (7, (189, 124, 190, 255)), (1, (255, 199, 161, 255)), (13, (255, 183, 134, 255)), (3, (255, 152, 82, 255)), (2, (255, 156, 88, 255)), (32, (255, 143, 66, 255)), (5, (178, 102, 178, 255)), (6, (175, 96, 176, 255)), (8, (255, 129, 43, 255)), (4, (172, 90, 173, 255)), (1, (255, 168, 109, 255)), (1, (255, 153, 83, 255)), (1, (255, 174, 118, 255)), (1, (255, 172, 115, 255)), (1, (255, 148, 75, 255)), (8, (255, 244, 248, 255)), (1, (255, 130, 43, 255)), (5, (255, 205, 222, 255)), (1, (255, 210, 177, 255)), (1, (255, 170, 110, 255)), (1, (255, 157, 89, 255)), (1, (255, 197, 134, 255)), (13, (255, 155, 86, 255)), (3, (255, 137, 56, 255)), (2, (255, 138, 57, 255)), (11, (255, 227, 208, 255)), (1, (255, 190, 145, 255)), (2, (255, 155, 87, 255)), (1, (169, 84, 170, 255)), (4, (255, 202, 220, 255)), (6, (255, 139, 59, 255)), (1, (255, 128, 42, 255)), (1, (255, 158, 91, 255)), (1, (255, 198, 158, 255)), (5, (255, 130, 44, 255)), (1, (255, 202, 165, 255)), (1, (255, 187, 154, 255)), (1, (255, 132, 48, 255)), (1, (255, 154, 84, 255)), (1, (255, 235, 241, 255)), (7, (255, 135, 53, 255)), (62, (255, 159, 93, 255)), (2, (255, 177, 124, 255)), (4, (255, 187, 210, 255)), (11, (255, 251, 248, 255)), (1, (255, 229, 211, 255)), (1, (255, 208, 176, 255)), (1, (255, 133, 50, 255)), (2, (255, 219, 231, 255)), (2, (255, 141, 63, 255)), (2, (255, 146, 71, 255)), (1, (255, 160, 95, 255)), (2, (255, 184, 135, 255)), (1, (255, 208, 175, 255)), (1, (255, 139, 61, 255)), (1, (255, 189, 211, 255)), (2, (255, 145, 69, 255)), (263, (255, 191, 147, 255)), (4, (255, 187, 141, 255)), (3, (255, 250, 252, 255)), (1, (255, 147, 72, 255)), (5, (255, 177, 203, 255)), (1, (255, 169, 109, 255)), (62, (255, 207, 174, 255))]
((163, 255), (73, 255), (14, 255), (255, 255))
(255, 127, 39, 255)
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(5) 图像粘贴操作(paste)
image.paste(im,box=none,maske=none)
使用im粘贴到原图片中。注意:两个图片的mode和size要求一致,不一致可以使用convert()和resize()进行调整。
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# -*- coding:utf-8 -*- from pil import image rawimg = image. open ( "qqtou.png" ) print rawimg.size im = image. open ( "number.png" ) print im.size # rawimg的size和im的size要相同,不然不能匹配 # paste(用来粘贴的图片,(位置坐标)),可以通过设置位置坐标来确定粘贴图片的位置 # 该方法没有返回值,直接作用于原图片 rawimg.paste(im,( 75 , - 90 )) rawimg.show() |
(6) 各种put操作
image.putalpha(alpha) - 添加多一层alpha层,没看出具体效果
image.putdata(data,scale=1.0,offset=0.0) - 添加一个像素序列到原图像。
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# -*- coding:utf-8 -*- from pil import image img = image. open ( "qqtou.png" ) img = img.convert( "l" ) img.show() 标签:
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