Posted: 2 Feb 2005

*note* For those of you who are Photoshop gurus, the beginning of this article will cover the basic concepts behind resizing an image, so you might want to skip down to the "let's resize" portion.

Differences between resizing your image and resizing your canvas

When I began my journey down the road of digital image manipulation, I didn't understand too much about photography so I had to learn a lot of basic concepts on my own. One of the concepts I wish someone had told me about was the difference between resizing an image (i.e. scaling an image) and resizing the canvas of the image.

• Resizing an image is equivalent to blowing an image up, or sizing it down. It's like making a 4 X 6 print out of a 8 X 10 print, or vice-versa. See example below:
  
  
  
  
• Resizing the canvas is equivalent to chopping off or adding on to the canvas of a painting. The actual image size doesn't change at all, unless you make the canvas too small; it then chops off part of the painting. You'll notice that in the example below, the lower image is just a cut of the upper image. Like it has been cropped.
  
  
  
  

Let's Resize

1. With The Gimp open, select the image you wish to resize
   
   
   
   When my image is open, my screen looks like this:
   
   
   
   Even though it's a bit hard to tell in this article, the image on my screen is really quite large. 1600x1200 pixels, to be exact.
   
   (pressing ctrl-alt-I will open an information window telling you the different specs of your image, as is seen below)
   
   
   
   To resize this image down to something that's usable, say, on a website, simply right-click anywhere on the image, and you'll see a menu pop up.
   
   Follow the menu to Image -> Scale Image
   
   
   
   When you click on that item, the following window will appear.
   
   
   
   Unless you're doing print work, the only things you'll have to worry about here are the things in the Pixel Dimensions box.
   
   Go ahead and type in your width dimension and press TAB.
   
   Upon pressing TAB, you'll notice the height is automatically adjusted to maintain the aspect ratio of the original image. This is done to make sure your image doesn't distort upon resizing.
   
   I chose 500 for my width.
   
   
   
   If you don't want the aspect ratio to be maintained, simply click on the "chain" icon
   
   
   
   and that will break the link between the width and the height of your image, letting you choose them independently of each other.
   
   Anyway... After you've chosen the width and height of your image, press OK and you'll see your image magically be resized!
   
   
   
   After you've resized it, you can save it or continue your manipulation any way you see fit!
   
   Keep your eyes open for more Gimp tips coming soon.