Skip to the tutorial
lil cactus

How to round the corners of an image

Beginner6 minutesUpdated

Quick answer

In Lil Cactus, draw a filled Rectangle with the Shape tool, then use Window then Properties to set its X (px) and Y (px) to 0, match its width and height to the photo and choose a Radius (px) (120 for the sample). Choose Layer then Arrange then Send Layer Backward, select the photo layer and choose Layer then Create/Release Clipping Mask. Export with File then Export then PNG… to keep the transparent corners.

The complete cloud photo before rounding and the same photo with four rounded corners showing transparent checkerboard
The photo shows only inside the rounded rectangle below it, and stays on its own layer. Drag the handle to compare.
Time
6 minutes
Level
Beginner
You need
An opaque photo, with no transparent areas to retain
Works with
JPG, PNG and WebP photos; export as PNG
Open the sample in Lil CactusUse your own photo

Free, no sign-up. Your photo stays on your computer.

A clipping mask uses the filled shape of the layer below as a window for the photo above. Here that window is a rectangle with rounded corners. You can change the rectangle later without drawing the curves into the photo itself.

Round the corners in five steps

  1. Open the photo and note its dimensions

    Open the sample from this page, or use File then Open… Choose Window then Properties. Note the photo’s Width and Height at the top of the panel; you will use them for the rectangle.

    Properties readout showing the sample document Width 1536 px and Height 1024 px
    These are the document dimensions.

  2. Draw a filled rectangle

    Choose Shape in the left toolbar. On the options bar, set Mode to Shape, Shape to Rectangle and Operation to New layer.

    Drag from near the photo’s upper-left corner toward its lower-right corner. The rectangle appears on a new Shape layer. Its temporary size can be rough: you will set exact bounds next.

    Lower toolbar from Pen through Hand, with the complete Shape button ringed
    Find the overlapping-square-and-circle icon near the bottom of the toolbar.
    Whole Mode Shape, Shape Rectangle and Operation New layer controls ringed
    Make a separate shape layer.

  3. Set the bounds and corner radius

    In Properties, under Geometry, enter X (px) 0 and Y (px) 0. For the sample, set Width (px) to 1536, Height (px) to 1024 and Radius (px) to 120. For your own photo, use the dimensions you noted in step 1. Press Tab after each number.

    Under Fill, set Paint to Color; under Stroke, set Paint to None. The rectangle now covers the canvas, with curved corners.

    Geometry with complete X 0, Y 0, Width 1536, Height 1024 and Radius 120 fields ringed
    Set the rectangle’s size here, not the document size.
    Fill and Stroke sections with both whole Paint controls ringed: Fill Color and Stroke None
    Use a filled shape without an outline.

  4. Clip the photo to the rectangle

    With Shape selected, choose Layer then Arrange then Send Layer Backward. Click the photo’s row in Layers (Background in the sample), directly above Shape. Choose Layer then Create/Release Clipping Mask.

    The corners now show checkerboard, which marks transparency in the editor and is not part of the export. A bent arrow beside the photo’s row in Layers shows it is clipped to Shape.

    Layers panel with the whole Background row ringed directly above the selected Shape layer
    Select the photo above the shape.
    Layers panel with the photo indented above Shape and a bent clipping arrow beside its thumbnail
    The photo is clipped to the shape below.

  5. Export the transparent PNG

    Choose File then Export then PNG…, enter rounded-sky.png in File name and click Export.

    Also choose File then Save As then Lil Cactus Project… to keep both layers editable; from then on, File then Save updates the project. Before that, File then Save writes back into the JPEG you opened as a flat image, with white corners because JPEG has no transparency; the first JPEG save opens Save Image. Export always writes a new file.

    Complete File name label and field ringed, showing rounded-sky.png
    Name the rounded copy.
    Export button ringed beside Cancel in the export dialog footer
    Export the image copy.

Change the corners later

In the project, click the Shape row in Layers. In Properties, change Radius (px) to 240 and press Tab for rounder corners. This changes the existing rectangle. The options-bar Corner radius field is for the next shape you draw.

Layers panel with the complete Shape row ringed below the clipped photo
Select the rectangle underneath the photo.
Geometry section with the entire Radius field ringed, showing 240
Use Radius in Properties to revise the existing shape.
Detail of a more rounded upper-left photo corner, with checkerboard in the hidden area
The larger radius hides more of the corner.

What to do next

Rounded image corners: questions and answers

Why did my rounded image get white corners in a JPEG?

JPEG cannot store transparency. In Lil Cactus, a JPEG export fills the hidden corners with white. Export with File then Export then PNG… or File then Export then WebP… instead to keep them transparent.

Can WebP keep the rounded corners transparent?

Yes. In Lil Cactus, choose File then Export then WebP… and click Export.

Does rounding corners change my image’s pixel dimensions?

No. This Lil Cactus workflow keeps the canvas dimensions. It hides corner pixels rather than resizing the image.

Why does a larger corner radius eventually stop changing the shape?

In Lil Cactus, the visible corner radius stops at half the rectangle’s shorter side. Beyond that, the same rounded shape is drawn even if the Radius field contains a larger number.

Can I round just one corner of an image?

Not with the Radius field: in Lil Cactus, a live Rectangle uses one Radius value for all four corners.

Published  · Last checked