Why a photo gets blurry after compressing, and what helps
How JPEG compression reduces file size, why a small KB limit causes blur and blocky edges, and practical ways to keep the face clear.
What compression does
JPEG makes files smaller by throwing away detail the eye is less likely to notice, such as fine texture and small colour changes. The lower the quality setting, the more it throws away. At very low quality you start to see blur, blocky squares and smudged edges.
Why small KB limits hurt
A KB limit fixes how much information the file can hold. If the pixel size is large and the limit small, each pixel gets very little space, so the compressor has to drop more detail. The same 30 KB looks sharp at 200 × 230 px and poor at 1000 × 1200 px.
JPEG quality, briefly
JPEG quality is usually given as a percentage. Around 80–95% looks close to the original, while below about 50% artefacts become visible on faces and text. PhotoSize searches between 95% and 30% and keeps the highest quality that stays under your limit, and the result line shows the quality it used.
Use the smallest pixel size your form allows
If the form gives a range or only a KB limit, a smaller pixel size usually looks better at the same KB. If the form sets exact pixels, use exactly those. Cropping tighter around the face also helps, because less background means more of the file goes to the face.
Start with a better photo
Even daylight and a plain light wall make a photo easier to compress. Shadows, noise from a dark room and busy backgrounds all use up KB without adding anything the form needs. A sharp, steady photo also survives compression better than a slightly blurred one.
Check before you upload
Look at the preview and the result line before downloading. If the quality is very low or the face looks soft, crop tighter, use a smaller pixel size if allowed, or retake the photo in better light. If the tool says it can’t fit, the limit is too small for that pixel size.
Questions
Why does my photo become blurry when I reduce the KB?
Reducing KB forces JPEG compression to discard detail, and a large pixel size with a small KB limit leaves very little room per pixel. Use a smaller pixel size if allowed, crop tighter, and start with an evenly lit photo.
What JPEG quality is good enough for a form photo?
Around 70% or higher usually looks clear for a face at form sizes. PhotoSize always picks the highest quality that stays under your KB limit and shows it in the result.
Can I compress a photo without losing quality?
Not to a small KB limit; JPEG compression always removes some detail. You can keep the loss low by using fewer pixels, a plain background and good light, so the file needs less compression.
Updated 2026-11-06