Sometimes a picture needs breathing room rather than a crop. Padding adds space outside the source, preserving its dimensions and content inside the new canvas.
Use Image Canvas Padding to enter an equal padding amount for all four sides and a background colour. The output becomes larger by twice that amount in each dimension.
Calculate the new canvas first
A 400 by 300 picture with 30 pixels of padding becomes 460 by 360. Thirty pixels are added on the left and right, then another thirty on the top and bottom.
The original picture is not scaled down to make room. Its content stays at the same source resolution. Transparent areas are composited onto the chosen background in this layout.
A white background can work for a document style presentation, while a coloured background may suit a social card. The colour is a visual choice, not a guarantee that an application will accept the file.
Padding differs from a border
A border drawn inside the image covers edge pixels without increasing the dimensions. Padding adds pixels outside it. Choose the operation that matches whether you need a larger canvas or simply an edge treatment.
Large padding amounts can push the output beyond the maximum canvas dimensions or total pixel budget. Reduce the padding or resize the source when that happens.
In a batch, every file receives the same number of pixels on each side. Different sources will still have different final dimensions; padding does not make a mixed set uniform.
Inspect the output with its intended background in mind. A pale edge may disappear against a white webpage even though it is clearly present in the file. The download dimensions are the quickest way to confirm that space was added correctly.