前言
在图像处理领域中,去马赛克(Demosaicing)是一项关键技术,用于从单色彩滤波阵列(CFA)图像恢复全彩图像。本文将介绍一种简单的线性插值去马赛克算法,并将其从MATLAB代码转换为Python代码。最终结果将展示如何从Bayer格式的图像数据恢复出RGB全彩图像。
什么是马赛克图像?
马赛克图像是一种通过在传感器上覆盖彩色滤光片阵列(CFA)生成的单通道图像。最常见的CFA模式是Bayer模式,其中包括红(R)、绿(G)和蓝(B)三种滤光片,以特定模式排列。去马赛克过程就是从这种单通道图像中恢复出三通道(RGB)的彩色图像。
算法简介
本文实现的去马赛克算法是基于简单线性插值的。它利用邻近像素的值来估计每个像素点的RGB值。具体步骤如下:
- 读取原始Bayer图像数据:从文件中读取Bayer图像数据,并进行必要的格式转换。
- 图像边界扩展:为了方便计算边缘像素的插值,我们对图像进行边界扩展。
- 线性插值计算:根据像素的不同位置(R、G、B),使用邻近像素的值进行插值计算,恢复出RGB图像。
- 显示结果:展示原始Bayer图像和插值后的RGB图像,并与原始彩色图像进行对比。
代码实现
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | import numpy as np import matplotlib.pyplot as plt def read_raw(file_path, bits, width, height): with open (file_path, 'rb' ) as f: raw_data = np.fromfile(f, dtype = np.uint8) bayer_data = raw_data.reshape((height, width)) return bayer_data def demosaic(bayer_data, width, height): # 扩展图像以便于计算边缘像素 bayer_padding = np.zeros((height + 2 , width + 2 ), dtype = np.float32) bayer_padding[ 1 :height + 1 , 1 :width + 1 ] = bayer_data bayer_padding[ 0 , :] = bayer_padding[ 2 , :] bayer_padding[height + 1 , :] = bayer_padding[height, :] bayer_padding[:, 0 ] = bayer_padding[:, 2 ] bayer_padding[:, width + 1 ] = bayer_padding[:, width] # 插值的主要代码 im_dst = np.zeros((height + 2 , width + 2 , 3 ), dtype = np.float32) for ver in range ( 1 , height + 1 ): for hor in range ( 1 , width + 1 ): if (ver % 2 = = 1 and hor % 2 = = 1 ): # Red pixel im_dst[ver, hor, 0 ] = bayer_padding[ver, hor] im_dst[ver, hor, 1 ] = (bayer_padding[ver - 1 , hor] + bayer_padding[ver + 1 , hor] + bayer_padding[ver, hor - 1 ] + bayer_padding[ver, hor + 1 ]) / 4 im_dst[ver, hor, 2 ] = (bayer_padding[ver - 1 , hor - 1 ] + bayer_padding[ver - 1 , hor + 1 ] + bayer_padding[ver + 1 , hor - 1 ] + bayer_padding[ver + 1 , hor + 1 ]) / 4 elif (ver % 2 = = 0 and hor % 2 = = 0 ): # Blue pixel im_dst[ver, hor, 2 ] = bayer_padding[ver, hor] im_dst[ver, hor, 1 ] = (bayer_padding[ver - 1 , hor] + bayer_padding[ver + 1 , hor] + bayer_padding[ver, hor - 1 ] + bayer_padding[ver, hor + 1 ]) / 4 im_dst[ver, hor, 0 ] = (bayer_padding[ver - 1 , hor - 1 ] + bayer_padding[ver - 1 , hor + 1 ] + bayer_padding[ver + 1 , hor - 1 ] + bayer_padding[ver + 1 , hor + 1 ]) / 4 elif (ver % 2 = = 1 and hor % 2 = = 0 ): # Green pixel (on Red row) im_dst[ver, hor, 1 ] = bayer_padding[ver, hor] im_dst[ver, hor, 0 ] = (bayer_padding[ver, hor - 1 ] + bayer_padding[ver, hor + 1 ]) / 2 im_dst[ver, hor, 2 ] = (bayer_padding[ver - 1 , hor] + bayer_padding[ver + 1 , hor]) / 2 elif (ver % 2 = = 0 and hor % 2 = = 1 ): # Green pixel (on Blue row) im_dst[ver, hor, 1 ] = bayer_padding[ver, hor] im_dst[ver, hor, 2 ] = (bayer_padding[ver, hor - 1 ] + bayer_padding[ver, hor + 1 ]) / 2 im_dst[ver, hor, 0 ] = (bayer_padding[ver - 1 , hor] + bayer_padding[ver + 1 , hor]) / 2 im_dst = im_dst[ 1 :height + 1 , 1 :width + 1 , :] return im_dst # ------------原始格式---------------- file_path = '../images/kodim19_8bits_RGGB.raw' bayer_format = 'RGGB' width = 512 height = 768 bits = 8 # -------------------------------------- bayer_data = read_raw(file_path, bits, width, height) plt.figure() plt.imshow(bayer_data, cmap = 'gray' ) plt.title( 'raw image' ) plt.show() im_dst = demosaic(bayer_data, width, height).astype(np.uint8) plt.figure() plt.imshow(im_dst) plt.title( 'demosaic image' ) plt.show() org_image = plt.imread( '../images/kodim19.png' ) plt.figure() plt.imshow(org_image) plt.title( 'org image' ) plt.show() |
结果展示:
总结
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