python PIL Image 图像处理基本操作实例
-牧野- 人气:01. 图片加载、灰度图、 显示和保存
from PIL import Image img = Image.open('01.jpg') imgGrey = img.convert('L') img.show() imgGrey.show() img.save('img_copy.jpg') imgGrey.save('img_gray.jpg')
2. 图片宽、高、通道模式、平均值获取
from PIL import Image import numpy as np img = Image.open('01.jpg') width, height = img.size channel_mode = img.mode mean_value = np.mean(img) print(width) print(height) print(channel_mode) print(mean_value)
3. 创建指定大小,指定通道类型的空图像
from PIL import Image width = 200 height = 100 img_white = Image.new('RGB', (width,height), (255,255,255)) img_black = Image.new('RGB', (width,height), (0,0,0)) img_L = Image.new('L', (width, height), (255)) img_white.show() img_black.show() img_L.show()
4. 访问和操作图像像素
from PIL import Image img = Image.open('01.jpg') width, height = img.size # 获取指定坐标位置像素值 pixel_value = img.getpixel((width/2, height/2)) print(pixel_value) # 或者使用load方法 pim = img.load() pixel_value1 = pim[width/2, height/2] print(pixel_value1) # 设置指定坐标位置像素的值 pim[width/2, height/2] = (0, 0, 0) # 或使用putpixel方法 img.putpixel((w//2, h//2), (255,255,255)) # 设置指定区域像素的值 for w in range(int(width/2) - 40, int(width/2) + 40): for h in range(int(height/2) - 20, int(height/2) + 20): pim[w, h] = (255, 0, 0) # img.putpixel((w, h), (255,255,255)) img.show()
5. 图像通道分离和合并
from PIL import Image img = Image.open('01.jpg') # 通道分离 R, G, B = img.split() R.show) G.show() B.show() # 通道合并 img_RGB = Image.merge('RGB', (R, G, B)) img_BGR = Image.merge('RGB', (B, G, R)) img_RGB.show() img_BGR.show()
6. 在图像上输出文字
from PIL import Image, ImageDraw, ImageFont img = Image.open('01.jpg') # 创建Draw对象: draw = ImageDraw.Draw(img) # 字体颜色 fillColor = (255, 0, 0) text = 'print text on PIL Image' position = (200,100) draw.text(position, text, fill=fillColor) img.show()
7. 图像缩放
from PIL import Image img = Image.open('01.jpg') width, height = img.size img_NEARESET = img.resize((width//2, height//2)) # 缩放默认模式是NEARESET(最近邻插值) img_BILINEAR = img.resize((width//2, height//2), Image.BILINEAR) # BILINEAR 2x2区域的双线性插值 img_BICUBIC = img.resize((width//2, height//2), Image.BICUBIC) # BICUBIC 4x4区域的双三次插值 img_ANTIALIAS = img.resize((width//2, height//2), Image.ANTIALIAS) # ANTIALIAS 高质量下采样滤波
8. 图像遍历操作
from PIL import Image img = Image.open('01.jpg').convert('L') width, height = img.size pim = img.load() for w in range(width): for h in range(height): if pim[w, h] > 100: img.putpixel((w, h), 255) # pim[w, h] = 255 else: img.putpixel((w, h), 0) # pim[w, h] = 0 img.show()
9. 图像阈值分割、 二值化
from PIL import Image img = Image.open('01.jpg').convert('L') width, height = img.size threshold = 125 for w in range(width): for h in range(height): if img.getpixel((w, h)) > threshold: img.putpixel((w, h), 255) else: img.putpixel((w, h), 0) img.save('binary.jpg')
10. 图像裁剪
from PIL import Image img = Image.open('01.jpg') width, height = img.size # 前两个坐标点是左上角坐标 # 后两个坐标点是右下角坐标 # width在前, height在后 box = (100, 100, 550, 350) region = img.crop(box) region.save('crop.jpg')
11. 图像边界扩展
# 边界扩展 from PIL import Image img = Image.open('test.png') width, height = img.size channel_mode = img.mode img_makeBorder_full = Image.new(channel_mode, (2*width, height)) img_makeBorder_part = Image.new(channel_mode, (width+200, height)) # 图像水平扩展整个图像 img_makeBorder_full.paste(img, (0, 0, width, height)) img_makeBorder_full.paste(img, (width, 0, 2*width, height)) # 前两个坐标点是左上角坐标 # 后两个坐标点是右下角坐标 # width在前, height在后 box = (width-200, 0, width, height) region = img.crop(box) # 图像水平右侧扩展一个ROI img_makeBorder_part.paste(img, (0, 0, width, height)) img_makeBorder_part.paste(region, (width, 0, width+200, height)) img_makeBorder_part.show() img_makeBorder_full.show()
12. PIL.Image 和 numpy 格式相互转换
from PIL import Image import numpy as np img = Image.open('01.jpg') array = np.array(img) # PIL.Image 转 numpy img1 = Image.fromarray(array) # numpy转 PIL.Image img1 = Image.fromarray(array.astype('uint8')) img1.save('from_array.jpg')
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