第二阶段主要涉及改善图像质量的一些图像处理技术，包括基本的图像变换、频域增强、彩色处理和图像恢复技术等。

In the second phase, techniques to improve the image quality are analyzed, and they are image transformation, frequency enhancement, color image, image recovery, and so on.

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该技术在空域将一幅待保密的彩色图像隐藏到另外一幅任意选取的足够大、可以公开的彩色图像之中，由所生成的图像可以无失真地恢复出原保密图像。

This technique is to hide a image into a lager enough 24 bits BMP image that can be public and selected with random, and the hiding image can be resumed without losing from the generated image.

youdao

该技术在空域将一幅待保密的彩色图像隐藏到另外一幅任意选取的足够大、可以公开的彩色图像之中，由所生成的图像可以无失真地恢复出原保密图像。

This technique is to hide a image into a lager enough 24 bits BMP image that can be public and selected with random, and the hiding image can be resumed without losing from the generated image.

youdao