anyone know how to replace colours in photoshop or illustrat

i have a bunch of coloured pencil sketches that i want to put together on one page.
but the scans all seem to have come out off-white. the paper that is

how can i put these together with the same white background?

replace the colour in photoshop or illustrator?

there are pencil shading sketches

you need to explain things a little more concisely…

but from what i gather, your scanned images haven’t turned out how it looks on the original… this could be many things. your screen probably isn’t colour corrected for starters. print out the image and see what it looks like in comparison to the original and the screen. if it prints to look more like the original, adjust your screen brightness and gamma.

in photoshop adjust the levels (black and white contrast), the colour balance, or the hue/saturation. these are found in the image menu, under adjustments…

in photoshop if you use the Levels menu item, you will see three eyedropper tools at the bottom right of the dialog box. if you select the one on the right (i think it is a white eyedropper), and then click on the paper area in your file that should be white, it will adjust the area to be bright white.

depending on the quality and overall color balance of the scan, this is a quick way to fix scanning problems where the backround is too dark or somewhat colored. if the rest of the drawing also needs color adjustments, you are better off using the color balance or replace color tools.