譬如说，看看上面这两幅图像。

Take, for example, the two images above.

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第四步：在心里把两幅图像相关联。

Step 4: Mentally chain the two images together.

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这样，可将图像的合成看作两幅图像互补的灰度变换的叠加。

Thus, we propose that the blend of a full-color image can be viewed as superposition of two complementary gray - level transformation images.

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