>>1899868I counted the colors in your image, and there were 58,766!
These are almost 99% just JPEG artifacts!
In fact, in the white portions alone, you have about 55,000 unique colors!
I deleted the white portions so that they contained no artifacts. This left 2,135 colors in the purple portions. I then reduced the total colors of the image to 256. Since your image has anti-aliasing, this is why you need more than just white and purple. I then saved as PNG.
Now the image only takes up half the space, while having approximately zero artifacts in the white space. However, this is just a partial repair to your image that has been damaged by the JPG format. Ideally what you should do going forward, is just save as PNG to start with. PNG is a lossless format that preserves all of the original image data, whereas JPG corrupts the original data
JPG makes since for images that truly need thousands of colors, such as basically all photohraphs. But for images that need less than 256 colors, and especially images that only need 2 colors, you should always use PNG
