Round Image Corners

What This Tool Does

This tool takes a source image and applies a rounded rectangle mask. You control the corner radius and the margin around the image. The output is a new PNG file with the same pixel dimensions as the source plus twice the margin in width and height. The corners are clipped to the rounded shape, and the area outside the rounded rectangle is either transparent or filled with a solid color you choose.

Controls and Inputs

The interface provides the following controls:

• Corner radius: a slider or numeric input from 0 to 1000 pixels, default 40.
• Margin: a slider or numeric input from 0 to 1000 pixels, default 0.
• Background mode: radio buttons for transparent background (selected by default) or solid background.
• Background color: an always-visible native color picker, defaulting to #ffffff; its value is used only in solid mode.

There is no separate control for per-corner radius, border width, shadow, or batch processing. The tool processes one image at a time.

Processing Rule and Output Dimensions

The output canvas width equals the source width plus twice the margin, and the height equals the source height plus twice the margin. A rounded rectangle is drawn at the margin offset, and the source image is clipped to that shape. The effective corner radius is limited to half the smaller dimension of the source image. If you enter a negative radius, it is treated as zero.

For example, a 200 by 100 pixel source with a radius of 80 and a margin of 10 produces a 220 by 120 pixel output. The effective radius is 50 pixels because the source height is 100, and half of that is 50. With a radius of 40 and margin 0, the output remains 200 by 100 pixels.

Background and Transparency

In transparent mode, the margin and the clipped corner areas are left transparent. In solid mode, the entire output canvas is first filled with the chosen color, and then the clipped image is drawn on top. This means the solid color appears in the margin and outside the rounded corners. The output is a PNG file, which supports transparency. JPEG is not an output option.

Step-by-Step Usage

1. Load your image.
2. Adjust the radius and margin.
3. Select background mode and color if needed.
4. Click Generate.
5. Review the result and download the PNG.

You can press Generate again after changing any control to update the preview.

Practical Checklist

• Keep the original image file as a backup.
• Check the corners for the desired roundness.
• If using a solid background, ensure sufficient contrast with the image.
• Remember that the source image is not resized; only the canvas size changes.

Frequently Asked Questions

Can I set different radii for each corner?

No, the tool applies the same radius to all four corners. There is no per-corner control.

What happens if I enter a radius larger than half the image size?

The effective radius is automatically limited to half the smaller dimension of the source image. For example, a 200x100 image with a radius of 80 will use an effective radius of 50 pixels.

Why is the output a PNG and not a JPEG?

PNG supports transparency, which is essential for rounded corners with a transparent background. JPEG does not support transparency, so it is not offered as an output format.