You can adjust the color difference before saving.
1, after opening the picture, the picture is in RGB mode. You can clean the picture first, and use the rubber stamp tool to clean the dirty and incomplete places.
2. After changing the size, you can copy a file, change the color mode of the new file to CMYK, and then compare it with the previous pictures, mainly color contrast, and then adjust their colors to be as close as possible to the brightness and saturation of RGB.
3. If you save the file, you should save it as a TIFF file. Because the file size of this format will not change after being imported into other typesetting software.
4, in fact, the size of the picture, you'd better adjust the size in the typesetting software, and then change it according to its actual size in PS, so that after you save it in TIFF format, it will still be the same size after import.