Image format, dimensions and quality: which should you change?

Meet image upload requirements by choosing the file format, setting pixel dimensions and adjusting compression in the right order.

Updated October 4, 2026

Read the upload requirements separately

An upload form may specify a format, pixel dimensions and a file-size limit. These are three different constraints. Converting HEIC to JPG can satisfy a format requirement without changing width or height. Resizing changes dimensions, while quality settings affect compression for lossy formats.

Write down all three requirements before editing. Keep the original image so that you can start again without repeatedly processing a lower-quality copy.

Choose an accepted format

JPG is widely accepted for photographs. PNG is useful for lossless image storage, while WebP can be a practical option when the destination supports it. Converting to a lossless format does not restore detail that was already lost.

FolioSprint’s image conversion workflow writes RGB still images. It does not preserve transparency or animation. Use a different workflow when those features are required, and keep the original asset.

Set the dimensions

Keep proportions fits the full image inside the requested width and height. One dimension can be smaller than the box because the aspect ratio stays the same.

Crop to fill produces the requested rectangle by trimming excess image area. Inspect faces, text and other important content near the edges. Increasing pixel dimensions does not recover missing detail from a small or blurry source.

Adjust quality after resizing

For JPG or WebP, a lower quality value can reduce file size at the expense of detail. Try a moderate setting, download the result and compare it with the upload limit.

PNG does not respond to a JPEG-style quality control in the same way. If the file remains too large, consider smaller dimensions or another accepted format rather than repeatedly changing a setting that has little effect.

Check the final file

Confirm the downloaded extension, dimensions and byte size. Open it at the size the recipient will use and inspect small text, sharp edges and faces. Upload the reviewed copy, keeping the original until you know the result is suitable.