What Image Compression Changes—and What It Cannot Guarantee

Smaller files involve trade-offs

Image size depends on pixel dimensions, image detail, color information, and the chosen encoding. Lossy encoders reduce some information to make a smaller file. At higher compression, artifacts may appear around edges, textures, or gradients.

A target size is not a guarantee: a detailed photo may remain larger than a simple graphic at the same quality setting. Repeatedly saving already compressed files can also compound visible degradation.

Review the copy before using it

Compare the output at the size where it will be displayed. Check small text, faces, sharp edges, and areas with subtle color transitions. Keep the original file so you can create another export if the first is too soft.

CalcPool's local image processing tool offers a preview and reports when a target could not be reached. The output is a separate download, and the original remains unchanged.