Trim and Reveal All in Paint by Zaweba
Image > Trim in Paint by Zaweba cuts away transparent or plain edges on chosen sides, and Reveal All grows the canvas to show pixels that sit outside it.
Two small commands in the Image menu save a lot of fiddly cropping. Trim cuts away empty edges for you. Reveal All does the opposite, growing the canvas so nothing hangs off the edge. Both are in Paint by Zaweba and both take a single dialog.
Trim
Image > Trim removes edges based on either transparency or the colour of a corner pixel. Choose transparency and it cuts away transparent margins round the content. Choose a corner colour and it cuts away the band of that colour, such as a white border, round the picture.
You also choose which sides to trim: top, bottom, left and right, in any combination. That matters when you want to keep space on one side, for example trimming everything except a margin at the bottom where a caption will go.
When Trim earns its keep
Cut-outs are the main use. After removing a background you often have a small product in the middle of a large transparent canvas. Trim on transparency shrinks the canvas tight round the product, which makes it easier to place in layouts and keeps file sizes down.
Scanned or screenshotted images with plain borders are the other. A screenshot with a white margin, a scan with a band of scanner lid round the photo, a chart exported with too much padding: trim on the corner colour cuts them back neatly.
It is also handy for icons and logos, where you want the edges of the canvas to sit exactly on the edges of the artwork before you add any padding of your own.
Reveal All
Sometimes parts of a layer sit outside the canvas. You may have moved a photo partly off the edge, scaled something up beyond the frame, or pasted a large image into a smaller document. The pixels outside the canvas are still there but you cannot see them.
Image > Reveal All grows the canvas to include them. Afterwards the canvas is big enough to show every pixel on every layer.
When Reveal All helps
Collages and composites, where pieces have spread beyond the original frame and you want to see the full extent before choosing a crop. Pasted images that came in larger than the document. Recovering parts of a layer you had pushed out of view and then wanted back.
Reveal All followed by Trim is a neat combination. Reveal All shows everything; Trim on transparency then cuts the result tight round the content. Together they give a canvas that fits your artwork exactly, with nothing hidden and no empty margin.
Things to watch
Trim on a corner colour looks only at that colour. If a photo's edge has a plain sky that matches the corner, Trim may cut into the sky. Use transparency mode for cut-outs, and check the result. Trim and Reveal All both change the canvas size, so if you are working to a fixed size for print or a web slot, do them before setting the final size, or use Canvas Size afterwards to bring it back.
Their neighbours
The Crop tool is for choosing a composition by eye. Canvas Size adds space in a chosen direction with an anchor and a fill. Crop to Selection is for cropping to a particular selected area. Trim and Reveal All are the automatic ones, and in Paint by Zaweba they spare you from dragging crop handles to the exact edge of your content.
