How to crop a JPG losslessly
- Open a JPG — lossless mode is already on.
- Drag the crop; its top-left corner snaps to the JPEG block grid shown while you drag.
- Press Crop Picture. The result panel confirms “Lossless — no quality lost”.
Why re-encoding loses quality
A JPG is not a grid of pixels; it is a compact description of 8 × 8 blocks with fine detail rounded away. Opening a JPG, cropping it and saving again rounds away detail a second time, and the damage shows as smeared edges and blocky skies — worse every time it happens.
How lossless crop works
Lossless mode never turns the JPG into pixels at all. It reads the compressed blocks, keeps the ones inside your crop, and writes them into a new file with the same compression tables and colour profile. The result is exactly what your camera saved for that part of the picture, usually in a smaller file than a normal re-save.
Rotating by 90° and flipping are lossless too. When a flip or rotation would put a partial block on the leading edge, the crop is trimmed to whole blocks — the panel tells you before you save.
Works with baseline and progressive JPGs from cameras and phones. Need an exact position or an odd angle instead? Turn lossless off and use high-quality JPG output.
Frequently asked questions
Is lossless crop really lossless?
Yes. The part you keep is carried over as the same compressed data — never decoded and re-compressed — so it decodes to exactly the same pixels. Every release is tested against a reference implementation.
Why does my crop snap to a grid?
JPG stores pictures in 8- or 16-pixel blocks, and a lossless cut has to start on a block edge. The top-left corner snaps to the nearest one; the faint grid shows where the edges are while you drag.
Why is straightening unavailable in lossless mode?
Straightening by a small angle means calculating new pixels, which requires re-encoding. Quarter turns and flips can be done losslessly, so those still work.
Does it keep my camera's colour profile?
Yes — the embedded colour profile is kept. Location and other metadata are removed.