How to Compress Images Without Obvious Quality Loss

First set the pixel dimensions to the largest size at which the image will actually be shown. This often produces a large reduction without introducing the block artifacts associated with very low quality settings.

Do not upscale a small source in the hope of adding detail. MDN warns that scaling can make images blurry or grainy, especially when text must remain legible.

Use JPG or lossy WebP for photographs and gradients. Use PNG or lossless WebP for logos, interface screenshots, diagrams, and transparent artwork. Converting a detailed photograph to PNG can increase size without improving the visible source.

Google reports that its WebP format supports lossy and lossless modes, transparency, and animation. Its published comparison found smaller files than comparable JPEG and PNG images under its test conditions, but your own image should be compared visually before replacing a production asset.

Compare the original and compressed image at the intended display size, then zoom into faces, small text, hair, foliage, and high-contrast edges. These areas reveal smearing and ringing before large smooth areas do.

Keep the original as the editing master. Compression output should be a delivery copy, because repeatedly editing and exporting a lossy file compounds degradation.