Image compression reduces the amount of data needed to store an image. The important part is deciding how small the file needs to be and what visual quality the destination requires. A good compression workflow does not aim for the smallest possible number; it aims for a file that is small enough without becoming visibly worse.
Start with the destination
An email attachment, profile image and full-screen photograph have different requirements. A 4000-pixel photo may be unnecessary when the image will appear in a small card. Before compressing, ask whether the image is oversized for the place where it will be used.
Compression and resizing are different
Compression changes how image information is encoded. Resizing changes the number of pixels. If an image is physically too large in dimensions, compression alone may not solve the problem. If the dimensions are appropriate but the file is too large, compression may be the better first step.
A practical workflow
- Keep the original file.
- Check the destination's maximum file size and pixel dimensions.
- Resize if the image has far more pixels than necessary.
- Compress the working copy.
- Open the result and compare important details at normal viewing size.
- Stop when the file is comfortably within the destination limit.
Why “maximum compression” is not always better
More aggressive compression can produce a smaller file, but it may also create visible artifacts around text, edges, faces or high-contrast details. The right setting depends on the image. A photograph can tolerate different compression than a screenshot containing small text.
When WebP can help
For web workflows, WebP can be an efficient output format when the destination supports it. For a general-purpose upload or email, JPG is often more predictable. Always check the destination before changing formats.
How to tell if compression worked
Compare the original and compressed files by file size, dimensions and visual appearance. A useful result is one where the file meets the technical limit while the image still looks correct at the size people will actually see. Do not judge only by the percentage reduction.