How does ps eliminate red handprints?

Ps The steps to remove the red seal on the picture are as follows:

1. First, we scan the required file into the computer, then save it, open the PS software on our computer, and directly pull the picture to the PS page to open it or press the shortcut key "ctrl+o" to find the file and then open it.

Now we see that this is a black and white document with a red seal in the middle. Now we need to remove it, and we need to use the channel tool in PS software. Click "Window" to find an option in the middle, and click "Channel" to open it.

3. At this moment, we see a channel window on the right. There are three color channels of red, green and blue, which also shows that the picture is also composed of three colors of red, green and blue.

4. If we need to delete the red color in the picture, we only need to click on the red channel, so other channels will be closed.

5. Click Image > Mode > Grayscale, and click OK in the pop-up dialog box to throw away other channels, so that we can turn this picture into black and white.

6. Now let's go back to our channel. Now there is only one channel left in our channel. Now, we can save or print this picture instead of this red stamp.

7. click file > save or press the shortcut key ctrl+s to click save, select a good location, click save, and click ok in the pop-up dialog box.