XF 1.5 Child style & image change question


I'm new to the admin side of XF and have a question regarding child style.

I am going to make some changes to a style so I know it is best to create a child style so my changes won't be lost in an upgrade of that style.

However, if I want to change some of the colors of the images/icons (in photoshop) and change a couple of the images a style uses to fit my style needs, so how would be the best way to do that so the changes aren't lost on style upgrades? A child style would still use the parent style's images if I am correct, so I don't know how to have the child use a different set of images.

I can copy the image/icon and make the changes to the copy and not the original but don't know where these should go.

I am pretty sure I have confused some of you, sorry for that.

I just don't know how to do this exactly as this is something new to me. Any and all help will be greatly appreciated.