Use Liquid Rescale to make an image fit your desktop

My camera takes pictures with an aspect ratio of 4:3, meaning if you shrank the picture so it was 4 inches across, it would be 3 inches high. Unfortunately, that means if I used it as the desktop background on a widescreen, 1080p monitor, either the top and bottom of the picture would get cut off or there would be blank space on the sides.

Goal

I want to make the picture fit the display perfectly without cropping it. I have two options in GIMP: use the traditional scale tool, which will stretch the image horizontally, or the Liquid Rescale plugin, which is designed to leave a photo's important features intact while stretching the less important areas. The scale tool causes a lot of distortion, though, while Liquid Rescale keeps things like faces, letters and buildings their original shape. Liquid Rescale comes with lisanet's version of GIMP.

Walkthrough

1. I found a picture of a damselfly that I wanted to resize. Find your picture, check that it's a different shape from your display, right-click it in the Finder, and select Open With > GIMP.
2. Go to the list of layers on the right side of the GIMP window, and click the Duplicate Layer button. If you keep making changes and then decide you don't like it anymore, you can delete the layer you modified and revert to your original photo.





3. Click Layer > Scale Layer... in the menubar, and click the chain link button next to the width and height entries until it looks connected, not separated, to force it to keep the same aspect ratio for the image. Then enter 1080 next to "height," and click Scale. This step is simply to set it to the right height for my display; substitute your display's height in for 1080.






4. Next, go to Layer > Liquid rescale... The controls on the left are familiar from the Scale tool, but this time click the chain to break the link. This lets you stretch it. Enter a new width of 1920, and click OK. The controls on the right are for fine-tuning the Liquid Rescale process and don't need adjusting in this example.

5. Go to File > Export to save the image as a .jpg or .png. Enter the name you want, followed by either the .jpg or .png suffix, and choose the folder you want it to go to. Hit Export, and then in the next window click Export to confirm the file size you want. When you try to quit GIMP after exporting, it will warn you that your picture has unsaved changes. It is OK to dismiss this by clicking Discard Changes as long as the picture has been exported.

Result

From top to bottom: Unmodified image, image with regular scale applied, image with Liquid Rescale applied. Liquid Rescale clearly doesn't stretch the important parts, the flower and the damselfly, as much as the regular scale tool. It stretched the grass in the background instead, a less noticeable alteration.

Learn More

A simple web search will turn up more articles on how to use the Liquid Rescale plugin. I have not based this on any of them.

Check out the project's website.

This article explains the process and tells how to mask important features before rescaling, to protect them.

I might choose to go deeper into Liquid Rescale's options in the future, so stay tuned.