GIMP Tutorial – How to Adjust the Size of any Image
GIMP is an extraordinary free image manipulation program which comes packed with a lot tools to do any photo retouch or edition you can think of, from format conversion to color adjustments, from brushes to image cropping. GIMP also boasts layer support and a comprehensive list of filters you can use for photo enhancements and much more. Today I'm going to tell you about one of the most common and basic tasks you can do with GIMP which is image resizing.
As you can imagine, you need to have GIMP installed and running on your computer to be able to follow this tutorial, so, if you don't, just click on the big blue “Download” button on top of this page and follow the InstallIQTM installer instructions, you'll have GIMP running in a couple of minutes.
Now that you have GIMP on your PC, let's start with the image resizing. First of all open the image by going File > Open.. on the Image Window Menu. On the “Open Image” window browse to the folder where you keep the image you want to re-size.
Remember that when you open an image file on GIMP, the program will display that image in the best fitting size, which can sometimes be smaller than the actual size of the image. GIMP will show you if the image is zoomed and at which percentage in the bar below the image.
For this task we are going to use the Scale Tool, which is located on the Toolbox.
So, click on it select it and then click on the image, this will make the Scale dialogue box to appear. There you can enter Width and Height parameters. You can also select the units as you can see in the next screenshot.
If you want to preserve the image aspect you should then modify only the Width parameter and let GIMP calculate the Height in its corresponding proportion. If what you want is to turn a rectangle in square or vice versa then you should check our upcoming tutorial on image cropping.
As you can see in the next screen capture the image I used for this example is 2048 x 1536 and I want to reduce its size to the half.
I entered 1024 in the “Width” box and pressed enter and the “Height” adjusated automatically. You can also see how GIMP also shows a preview over the original image.
Once you are happy with the new size of your image, you just click the “Scale” button and GIMP will do it.
After that you have to match the size of the canvas to the new image size, go to Image > Fit Canvas to Layers and click on it.
Now all you need to do to make this change permanent is to export the image, go to File > Export and set the file format and location of the new image. For this example I chhose JPEG which is a really popular image file format.
If you want to keep the original image file you'll have to select a different name for the new file, if not GIMP will overwrite the old one.
Adjusting the size of any image is easy and straight forward and you do not need to have deep knowledge about GIMP or graphics manipulation techniques. In upcoming tutorials we are going to be sharing more tips and trick about how to make simple image edition and enhancements with GIMP, so, stay tuned!!