Crop Image

What cropping actually does

Cropping removes pixels from the edges of an image and keeps the rest. Nothing is scaled, nothing is generated, and nothing is invented, which makes it a genuinely lossless operation in the way that resizing and compressing are not. The image that remains is exactly the pixels that were there before. That is why cropping is a safe way to prepare a photo for a specific shape, and why it is preferable to resizing when the goal is to change how an image is framed rather than how large it is.

NoteCropping the same area twice gives a smaller image than cropping in one step. Choose the final frame in a single pass.

Fixed ratios versus a free selection

A fixed aspect ratio crops to a shape the platform expects, such as 1:1 for a product photo or 16:9 for a video thumbnail, and the result is predictable. A free selection lets you drag exactly the frame you want, which is more flexible but easy to get subtly wrong. For anything going to a specific platform, use the fixed ratio. For choosing the most useful part of a photograph, drag it yourself and look at what you are keeping before committing.

• Fixed ratio: correct for a platform that expects a specific shape.
• Free selection: better for deciding which part of a photo matters.
• Drag a little inside the final frame. There is usually dead space at the edges.
• Check the faces and the horizon line, not just the corners of the frame.
• Look at the preview before exporting, not after.

Why not just resize instead

Resizing and cropping solve different problems and the distinction matters more than it sounds. If you need an image to display at 800 pixels wide, resizing is right and cropping changes nothing useful. If you need a portrait photo to become a square without distortion, cropping is the answer, because resizing alone would stretch it. A common mistake is resizing a portrait image to a square, which distorts faces. Crop to the ratio first, then resize to the size, and the proportions stay correct at both steps.

• Change the shape: crop. Resizing will distort the proportions.
• Change the size: resize. Cropping is not a substitute.
• Change the shape and the size: crop first, then resize.
• A portrait photo made square by resizing will stretch faces.

NoteCrop and resize are sequential, not alternatives. Doing them in the right order avoids distortion entirely.

Cropping and the file it produces

A crop reduces the pixel dimensions and therefore usually reduces the file size, but it does not re-encode the image, so the quality of the kept pixels is untouched. What does happen is that the file is saved again, and if the output format is lossy such as JPG, that save is a fresh lossy step on the kept pixels. For a small crop from a large original this is not a practical concern, but it is one more reason to keep the original file rather than cropping an already compressed copy several times.

• Cropping alone does not touch the quality of the pixels it keeps.
• A smaller image usually means a smaller file.
• Saving as JPG is a lossy step, even though the crop was not.
• Keep the original. Crop again from it rather than from a previous crop.