What Is Lossy vs Lossless Image Compression?

Lossy compression reduces file size by discarding some information. Lossless compression reduces redundancy without discarding the underlying image information.

What to do

Use lossless methods when exact pixel fidelity matters. Use lossy methods when a smaller file is more valuable and minor visual differences are acceptable. The simplest next step is to Compress Image. If the issue is actually about jpg vs png, see JPG vs PNG as well.

Why this happens

Image problems often come from three separate variables: pixel dimensions, encoded file size and file format. Changing one does not automatically solve the others. A very large photo may need resizing even when its format is already JPG; a transparent graphic may need PNG or WebP even when the file size is acceptable; and an upload limit may be measured in megabytes rather than pixels.

Before editing, check the requirements of the place where the image will be used. That gives you a concrete target and reduces unnecessary quality loss. When possible, keep the original file and create a delivery copy for the specific destination.

Common questions