Magento 2 Visual Swatch Image: Background of image is removed after upload

Question

This is the image that I upload to display on a visual swatch:

However, it uploads and displays like this:

How do I get the image to upload with the background intact? You can view the uploaded image here: https://store.gnut.com.au/pub/media/attribute/swatch/swatch_image/30x20/c/r/cream1.png

I intend to increase the swatch size to 90x90px but I'll have to change themes away from Luma first. Could the uploader be removing the background accidentally due to the small swatch size?

Answer 1

After changing all files to a .jpg extension instead of .png the problem went away.