Instagram-1917滤镜

前言
Instagram-1977滤镜颜色偏暖，很受欢迎。本文主要参考了这篇文章。

颜色映射表
文章中的颜色映射表我使用相同色值的图片来代替。使用OpenCV生成图片代码:

# 生成图片
# src:图片保存路径
def mapImageGenerator(src):
  r = np.array([[81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 81, 82, 84, 84, 85, 86, 88, 88, 89, 91, 92, 93, 93, 95, 96, 97, 98, 99, 100, 101, 103, 103, 104, 106, 107, 107, 108, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 121, 122, 123, 125, 126, 126, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 140, 140, 141, 143, 144, 145, 145, 147, 148, 149, 150, 151, 152, 154, 154, 155, 156, 158, 159, 159, 161, 162, 163, 164, 164, 165, 166, 167, 168, 169, 170, 171, 173, 173, 174, 176, 177, 178, 178, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 191, 192, 192, 193, 195, 196, 196, 198, 199, 200, 201, 202, 203, 204, 206, 206, 207, 208, 210, 210, 211, 213, 214, 215, 215, 217, 218, 219, 220, 221, 222, 223, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225]])
  g = np.array([[57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 73, 74, 75, 76, 77, 78, 79, 80, 81, 83, 84, 85, 85, 86, 87, 88, 89, 90, 91, 93, 94, 95, 96, 96, 97, 98, 99, 100, 102, 103, 104, 105, 106, 107, 108, 108, 109, 110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 120, 122, 123, 124, 125, 126, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 142, 143, 143, 144, 145, 146, 147, 148, 149, 150, 152, 153, 154, 155, 155, 156, 157, 158, 159, 160, 162, 163, 164, 165, 166, 167, 167, 168, 169, 170, 172, 173, 174, 175, 176, 177, 178, 179, 179, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 202, 203, 204, 205, 206, 207, 208, 209, 210, 212, 213, 214, 214, 215, 216, 217, 218, 219, 221, 222, 223, 224, 225, 226, 226, 227, 228, 229, 231, 232, 233, 234, 235, 236, 237, 237, 238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 249, 251, 252, 253, 254]])
  b = np.array([[64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 65, 66, 68, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79, 80, 82, 83, 84, 85, 86, 87, 89, 90, 91, 92, 93, 95, 96, 97, 98, 99, 100, 102, 103, 104, 105, 106, 107, 109, 110, 111, 112, 113, 115, 116, 117, 118, 119, 120, 122, 123, 124, 125, 126, 127, 129, 130, 131, 132, 133, 134, 136, 137, 138, 139, 139, 140, 142, 143, 144, 145, 146, 147, 149, 150, 151, 152, 153, 154, 156, 157, 158, 159, 160, 161, 163, 164, 165, 166, 167, 169, 170, 171, 172, 173, 174, 176, 177, 178, 179, 180, 181, 183, 184, 185, 186, 187, 189, 190, 191, 192, 193, 194, 196, 197, 198, 199, 200, 201, 203, 204, 205, 206, 207, 208, 210, 211, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212]])
  img = cv2.merge([b, g, r])
  img = img.astype(np.uint8) # 指明数据类型
  cv2.imwrite(src, img)

shader代码

  // 纹理坐标
  vec2 uv = fragCoord/iResolution.xy;
  // iChannel1中保存的是需要处理的图片
  vec3 col = texture(iChannel1,uv).rgb;
  // iChannel0中保存的是颜色映射表色值生成的图片
  vec3 resCol = vec3(texture(iChannel0,vec2(col.r,.0)).r,
                     texture(iChannel0,vec2(col.g,.0)).g,
                     texture(iChannel0,vec2(col.b,.0)).b); 
  fragColor = vec4(resCol,1.0);

最终效果

原图	1977