My first project with Go. A simple CLI image resizer.
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A really simple CLI image resizer.

Hi there, folks!

This is rsz, a simple image resize tool, with some cool features and a fluent syntax, that I built for two main reasons:

  • I am learning Go, so I need some simple training projects;
  • my girlfriend needed an image resize tool for her university projects;

Take a look to the "Usage" section to see rsz in action!

If you want to learn more about features, go to the file. I am going to update it at every release, also with future ideas. However, don't take it too much seriously: it's just a learning project.


Nothing really special, just go ahead with go install, or go install -ldflags '-s' to strip out debugging data and reduce final executable size.


Simple Resize

This will resize every image in the folder to a width of 1024. The height will be calculated accordingly.


Choose Resized Image Size

When not specified, a dimension will be calculated by maintaining proportions. If neither of them were specified, the width will be 1024px automatically and the height will be calculated accordingly.

rsz --width "800"
rsz --height "400"
rsz --width "800" --height "400"

Choose Output format

You can also convert the resized images to a certain format, if you want. Just use the "to" flag.

rsz --to "jpg"
rsz --to "png"
rsz --to "tiff"

Choose Output Sub-Directory

Maybe you have tons of image to resize and you just don't want to put everything in the same folder.

rsz --in "resized"

The resized images will be saved in current_dir/resized folder. This also works recursively:

rsz --in "resized/images/here"

Note: The default value for this flag, if not specified, is "resized". This means that if you execute rsz without the --in flag, resized images will be saved in the "resized" folder as a default.

Filter Input by Format

Let's say you have some JPEGs and PNGs, but you just want to resize the PNG files. No problem, just use

rsz --only "png"

and you're good to go!