How to compress a photo and signature for an online form

This is the single most common complaint, and it is a format problem rather than a settings problem.

A signature is line art: black strokes on a white background, with hard edges everywhere and no continuous tone. JPEG is built on the assumption that sharp transitions are rare, so it surrounds every stroke with ringing — faint grey echoes — and at the low quality needed to reach 10 or 20 KB those echoes become a visible haze.

Try PNG instead. A cropped black-on-white signature at modest dimensions is often under 20 KB losslessly, and it will be perfectly sharp rather than smudged. Check the portal accepts PNG first — many specify JPEG only, in which case crop tighter and keep the dimensions small rather than pushing the quality down.

Portals almost always specify the photo and the signature separately, with different dimensions and different size ranges — and often a minimum as well as a maximum for each.

Handle them as two separate jobs. Compressing both to the same target is the quickest way to have one of them rejected, and the error message will rarely tell you which.

Most rejected signature uploads are bad captures rather than bad compression.

• Even, indirect light. No glare band across the page, no hard shadow from your hand or phone.
• Camera parallel to the paper. An angled shot produces a trapezoid that cannot be corrected later without cropping into the signature.
• Fill the frame. Do not spend pixels on the desk around the page.
• Plain white paper, dark ink. Lined or tinted paper reduces contrast and confuses automated checks.

A kilobyte means 1000 bytes to some systems and 1024 to others, and portals do not say which. A file you measure at 49 KB can be read as 50.2 KB elsewhere.

Targeting a few per cent under the maximum removes the risk entirely, and costs you nothing visible.

You are handling a photograph of your own signature — a document worth protecting. Uploading it to a compression service puts a copy on infrastructure you cannot inspect.

The tools on this site process files in the browser, so nothing is transmitted. Whatever tool you use, it is worth confirming that before you upload a signature anywhere.