Crop Image

Cropping is the one edit that costs nothing

Almost every other thing you can do to an image is a trade. Compressing it throws away detail. Resizing it up invents pixels that were never captured. Filters, sharpening, colour correction — all of them alter what is there.

Cropping does none of that. It removes pixels and leaves the ones it keeps exactly as they were. A 4000 by 3000 photo cropped to the middle 2000 by 2000 gives you two thousand pixels of untouched original. No resampling, no interpolation, no generation loss. Crop the same file forty times and the forty-first is as sharp as the first.

That is worth knowing because it changes the order you should do things in.

Crop first, resize second

If you need a 1080 by 1080 square out of a photograph, there are two routes. You can hand the whole photo to a resizer and let it decide what to cut. Or you can choose the square yourself, then resize the result.

The second gives a better picture for two reasons. The obvious one is that you chose the composition instead of a centre-crop rule. The less obvious one is that you are scaling down from exactly the region you wanted, so every pixel of the output is derived from the part of the photo you cared about.

Do it the other way round — resize then crop — and you scale the whole frame down first, then throw most of it away, leaving fewer pixels than you started with.

The shapes worth locking

Freehand is right when the picture decides. A fixed ratio is right when the destination decides, and most destinations do.

Lock the shape before you drag and the frame can only ever be that shape, whichever handle you pull.

A crop is not private on its own

Worth saying because it catches people out. Cropping the corner off a screenshot genuinely removes those pixels from the file — this is not a redaction that can be undone by unrolling it, the way a black rectangle drawn on top can be.

But the parts you kept can still carry things you did not think about. A photograph may hold GPS coordinates and a camera serial number in its metadata regardless of where you put the frame. If the point of the crop is to publish something safely, that is a separate question from the crop itself.

Why the file gets smaller, and by how much

Keeping half the area of a JPEG usually gives roughly half the file, but only roughly. Compression works on the content, so a crop that keeps the busy half of a photograph and discards a plain sky will shrink less than the areas suggest. Saving as PNG can even make the file larger than the original JPEG, because PNG is lossless and the original was not.

If a size limit is the actual problem, crop first and then compress. They are different jobs and doing them in that order gives the compressor less to work with, which is what you want.

Nothing is uploaded

The image is decoded by your browser, drawn to a canvas, and written back out — all on your machine. There is no server involved, which is why there is no queue, no file size limit beyond your own memory, and no copy of your photograph sitting in somebody else's storage bucket afterwards.

For a holiday snap that hardly matters. For a screenshot of a bank statement, a photograph of a passport, or a picture of a child, it is the whole point.