Shotnest · Library
Review what a crop and a covered area leave visible
Crop removes everything outside a rectangle and redact paints one rectangle black; in both cases check every remaining pixel of the exported PNG.
Two operations, two kinds of leftover
The crop helper keeps one rectangle, given by its left edge, top edge, width and height in pixels, and discards the rest. The rectangle must fit inside the image; a 1170 × 2532 screenshot cropped from left 100 and top 2000 with width 1170 is rejected, because 100 + 1170 is wider than the image. The redact helper keeps the whole image and fills one rectangle with opaque black.
Crop can remove context the recipient needs, such as a date or a sender. Redact leaves all the context, including a second copy of the private detail somewhere else on the screen. Both helpers draw on a canvas element and save a new PNG, as described in the HTML Standard section on canvas linked below.
Both helpers work on one image at a time and keep the full resolution inside the rectangle; nothing is resized unless you also run the resize helper.
Make and inspect a sharing copy
- Decide what the recipient must see and what must not leave your phone.
- Choose crop when the useful part is one region; choose redact when the surrounding context matters.
- Enter the rectangle in pixels; for example left 0, top 300, width 1170, height 900 keeps a 1170 × 900 band.
- Open the downloaded PNG and check edges, status bars, notification banners and thumbnails.
- Share the reviewed copy, not the original.
- Crop · left 0, top 300, 1170 × 900
- 1170 × 900 result
- Crop · left 100, top 2000, 1170 × 900
- Rejected: rectangle outside image
What gets missed
- A name covered in the message but still visible in the header above it.
- A cropped price without the line that says which product it belongs to.
- An email address repeated in a small reply preview.
- Assuming the original file was edited; it remains unchanged.
You choose the rectangle
Neither helper reads text or looks for private information. They change pixels where you tell them to and nowhere else, in the browser tab, without uploading the image.
Accepted files are PNG, JPEG, WebP and AVIF images of up to 15 MB each; larger files or images over 12000 pixels on a side are refused rather than silently shrunk.