Image Perspective Correction

Image Perspective Correction removes perspective distortion from photographs taken at an angle. A whiteboard photographed from the side appears trapezoidal, but by marking the four corners you can transform it into a rectangle as if viewed straight-on.

The tool solves an 8-parameter projective transformation (homography) matrix via linear equations and applies inverse mapping with bilinear interpolation for pixel-accurate results. Use it to fix keystoning in architectural photography, straighten documents or receipts scanned with a smartphone instead of a scanner, or correct angled shots of signs and posters.

Output dimensions are automatically computed from the selected region. You can also specify a custom aspect ratio to match known proportions such as A4 paper or business card sizes. All processing runs locally on the browser Canvas — image data is never sent to any server.