Image Cropping

Image cropping removes the outer parts of an image and keeps a rectangular region. The crop is defined by an offset from the top-left corner plus a width and a height. The pixels inside the region are kept as they were.

Cropping reduces pixel dimensions without resampling, so the remaining content keeps its sharpness. A 2880×1800 screenshot cropped to its central 1600×900 region is 1600×900 pixels at the same detail.

For PNG, a crop is lossless. For JPEG, most editors decode and re-encode the image, which adds another round of lossy compression. Special tools can crop JPEG losslessly when the edges fall on the 8 or 16 pixel block grid.

Cropping vs resizing

Cropping removes content and keeps scale. Resizing keeps all content and changes scale. To make a screenshot smaller for a document, cropping keeps text readable, while resizing shrinks the text. The two are often combined: crop to the area of interest, then resize to the target width.

Where cropping is used

• Removing the menu bar, Dock or other windows from a screenshot.
• Focusing a guide image on the control the reader needs.
• Fitting an image to a required aspect ratio.
• Leaving private content outside the final image.

Cropping and aspect ratios

A free crop produces any ratio. A crop with a locked ratio, such as 16:9 or 1:1, keeps images in a series consistent. When the destination has a fixed ratio, crop to that ratio before resizing, or the destination crops it for you.

Cropping at capture time saves a step. Temposhot's Custom Area source has Lock aspect and ratio presets. In the Documents editor, framing levels Wide, Relaxed, Balanced, Close and Tight zoom into the area around the recorded action.

Common mistakes

• Cropping so tightly that the reader cannot tell where on screen the control is.
• Cropping each image in a series slightly differently.
• Relying on a crop in an editor that keeps the original pixels in the file. Export a new file before sharing.
• Cropping JPGs repeatedly and re-encoding each time.

Have an image to fix right now?

Cut an image into parts with Split Image, or check the result's size with Screenshot Resolution Checker.

Common questions

Is cropping a safe way to hide private information?

Cropping removes pixels when you export a new file. Check that the editor does not keep the original image as an editable layer.

Does cropping reduce quality?

Not for PNG. For JPG, re-encoding adds a small loss unless the tool crops losslessly.

Sources

• Cropping (image) (Wikipedia)

Related resources

• Annotations and framing: framing levels in the editor.
• Capture sources: capture only the area you need.