How does PS convert color photos into black and white?

Using Photoshop to convert color photos into black and white can be achieved through the Image menu bar. There are several specific methods (CS6):

1. Open the picture, click the adjusted black and white under the image menu bar, adjust the data as needed, and click OK.

2. Click "Mode" under the "Image" menu bar, select the gray color, and click "Throw away".

3. Click "Adjust" to remove the color under the "Image" menu bar, and the effect is shown in the following figure: