OpenCV实现图片编解码实践(对数的是)

原图：

图像信息,可以看到图像是一个816*2100像素的图片:

python代码：

import cv2
import numpy as np
import matplotlib.pyplot as plt
 
img = cv2.imread('11.jpg', 0)
img1 = img.astype('float')
img_dct = cv2.dct(img1)
img_dct_log = np.log(abs(img_dct))
img_recor = cv2.idct(img_dct)
recor_temp = img_dct[0:100,0:100]
recor_temp2 = np.zeros(img.shape)
recor_temp2[0:100,0:100] = recor_temp
print recor_temp.shape
print recor_temp2.shape
img_recor1 = cv2.idct(recor_temp2)
plt.subplot(221)
plt.imshow(img)
plt.title('original')
plt.subplot(222)
plt.imshow(img_dct_log)
plt.title('dct transformed')
plt.subplot(223)
plt.imshow(img_recor)
plt.title('idct transformed')
plt.subplot(224)
plt.imshow(img_recor1)
plt.title('idct transformed2')
 
plt.show()

仅仅提取一个100*100的DCT系数后的效果：

当用800*1000的DCT系数：

可以看到图像细节更丰富了一些：

import cv2
import numpy as np
import matplotlib.pyplot as plt
 
img = cv2.imread('11.jpg', 0)
img1 = img.astype('float')
img_dct = cv2.dct(img1)
img_dct_log = np.log(abs(img_dct))
img_recor = cv2.idct(img_dct)
recor_temp = img_dct[0:800,0:1000]
recor_temp2 = np.zeros(img.shape)
recor_temp2[0:800,0:1000] = recor_temp
print recor_temp.shape
print recor_temp2.shape
img_recor1 = cv2.idct(recor_temp2)
plt.subplot(221)
plt.imshow(img)
plt.title('original')
plt.subplot(222)
plt.imshow(img_dct_log)
plt.title('dct transformed')
plt.subplot(223)
plt.imshow(img_recor)
plt.title('idct transformed')
plt.subplot(224)
plt.imshow(img_recor1)
plt.title('idct transformed2')
 
plt.show()

当用816*1200的DCT系数：