Help me scale an image in Photoshop

February 20, 2009 6:18 AM

Help me scale an image so that part of it is a specific size using Photoshop CS3.

I've got an image, and I know that I need one part of that image to be a specific size in pixels, is there a way to scale the image so that that part is the correct size and the rest of the image scales appropriately?

I'm using Photoshop CS3 on a Mac.

I can do it by eye using free transform, but that's ridiculously time consuming, and not as accurate as I'd like. Is there another way to do this?

posted by featherboa to computers & internet (3 comments total)

Since you know the ratio of the portion-height to the full image-height, as well as the target portion height, you can work out the target full image size.
posted by devnull at 6:27 AM on February 20

Get the original dimensions of the area you want to resize. Say its 200 x 100.
Suppose you want to scale that part of the image down to 80 x 40...

This means you're scaling the entire image down to (80/200)*100 = 40% of its original size.

So you just scale the entire image down to 40% within Photoshop, and everything should be fine.

Note I only used the widths as a basic for the calculation. You could just as easily use the heights.
posted by le morte de bea arthur at 6:35 AM on February 20

Got it - thanks very much to both of you. I never really seem to think of using maths!
posted by featherboa at 6:53 AM on February 20