Better Scaling in Photoshop

Avoiding jagged edges when scaling images

Did you ever wonder why Photoshop sometimes creates jaggy edges when you scale down your images? Now, here is a small tutorial to create good looking down scaled images. Compare the following two images with the original file (jugs.jpg), which has an overall dimension of 1000 x 615 pixels. In this example, we want to scale it down to 435 x 268 pixels.

OK, let's scale it down. Launch Photoshop and load the "jugs.jpg" image. Open the image size dialog and make sure bicubic scaling is selected as well as constrain proportions. For width type in 435 pixels, the height will be set automatically to 268 pixels. Hit Enter and let's have a closer look at the result.

You should come up with a similar result like the image on the left. When you take a closer look at the edges, you'll see that they are not very smooth any longer and not very convincing at all.

We want to scale down our images in high quality, so everyone can see how much effort we put into our work.

Let's go a much better way. Go back to the last saved version or open the file once more. With the same activated properties in the image size dialog, scale down the image to 500 pixels width first, then, in step two, to a width of 435 pixels. Again, let's have a closer look at the image.

See what I mean? :-) The edges of the jugs are much smoother and more rounded and haven't any jaggies any more. Beautiful. This is what we want to achieve.

So what has happened?

Photoshop interpolates best between pixels when you scale down images by a factor of 2, 4, 8, 16 and so on (equal to 50%, 25%, 12.5%, 6.25%). So you need two steps to scale down your image properly (in this example 1. scale down to 500 and 2. from that size scale down to 435).

Try for yourself. I have tested this method with images that have rounded shapes and diagonal lines. It works fantastically. However, it isn't very effective and hardly noticable with rectangular objects and straight lines.

Tutorial and images copyright © sms 2002-2007.