Shape Overlay Tool

Place customizable geometric shapes like circles, rectangles, triangles, and polygons on images.

Tested tool guide Tested browser tools Checked August 16, 2026

What Shape Overlay Tool does and how it behaves

Shape Overlay Tool puts a configurable geometric form directly over a source image. Choose a circle, rectangle, triangle, or polygon, then adjust the form so its size, placement, and appearance suit the intended mark. The key distinction is that the shape is added above the picture. It is not a crop boundary, an automatic subject trace, or evidence that the marked object is geometrically exact. A polygon still consists of straight sides, even when used to approximate an irregular region.

How the result is produced

Shape geometry

The chosen geometry defines where the added mark can appear. A circle has a curved boundary, a rectangle has four right-angle corners, a triangle has three sides, and a polygon has multiple straight sides. Position and size determine which image region the form occupies. Increasing a polygon's sides can make its outline look smoother, but it remains a geometric approximation rather than an automatic trace.

Overlay behavior

The operation places the configured shape in front of the source picture. Its visual treatment controls whether it reads as a block, an outline, or a light annotation, subject to the controls the page presents. Changing the overlay does not make the photographed object itself circular, rectangular, triangular, or polygonal. The result is an annotated image, not a geometric analysis of the scene.

Good uses

Place a circle over a damaged component in an inspection photograph so a reviewer can find the relevant area without relying on a written location alone.
Add a rectangle over a screenshot or product image to identify a panel, control, label area, or other region with a clearly bounded shape.
Use a triangle or polygon to mark a hazard zone, diagram region, or irregular area that cannot be represented adequately by a circle or rectangle.

Limits and checks

A geometric shape does not identify the subject beneath it. Confirm the placement visually, especially when the marked region has an irregular or poorly defined edge.
Do not treat the overlay's dimensions as a real-world measurement unless the source image has been independently calibrated for scale, perspective, and lens distortion.
The shape can conceal or visually compete with image detail, depending on its appearance. Compare the result with the unmarked source before relying on small features.

Common questions

Can a polygon follow a curved or irregular edge exactly?

No. A polygon is composed of straight sides. Additional sides can approximate a curve visually, but the result is not the same as a freehand contour and does not certify the underlying boundary. Use the polygon when a faceted approximation is acceptable. Use a dedicated masking or tracing tool when exact edge following matters.

Does adding a shape crop the image into that shape?

No. This tool's purpose is to place a geometric element on top of the picture. The shape can emphasize or cover part of the image according to its appearance, but it should not be read as a crop instruction or a change to the photographed object's proportions. Use a crop or mask tool if the output boundary itself must take that shape.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.