CornerMask is a photo editor from Marco Polo Research Lab LLC. The app is not yet available on the App Store.
Straighten a photographed rectangle
- Open a photo or image file in CornerMask.
- Choose Perspective. Drag each hollow corner to the matching corner of your document, painting, poster, or sign.
- Use the outer magnifier for context and the inner circle for original pixels.
- Select Preview result to check the correction. Choose Edit corners to make further adjustments.
- Choose Save copy to Photos to create a separate full-resolution image.
Pixelate faces or another area
- Choose Faces and turn on Pixelate selected faces.
- Tap a detected face box to include or exclude it.
- Choose Draw missing area, then drag a rectangle over another area to conceal.
- Save a copy when the selected regions match your intended edit.
Edit inside Apple Photos
Open a still photo in Photos. Choose Edit → Extensions → CornerMask. On iPhone and iPad, Extensions is in the editing More menu.
Finish the CornerMask edit, then save the changes in Photos. Reopen CornerMask from Photos to adjust a recognized edit from the original image. Photos retains the original through its normal edit workflow.
Current formats and limits
Requires iOS/iPadOS 27 or macOS 27. Exports are SDR JPEG still images at their natural output dimensions. SDR means standard dynamic range.
HDR, RAW, and Live Photo preservation are not supported. Undo history and full-image zoom and pan are not included.
Supported photo metadata can remain in the output, including EXIF location data when present. See CornerMask app privacy.
Contact support
Email support@mprlab.com. Include your operating system version, the image format, the steps you took, and any error message.
Send a sample image only if you choose to share it. Support email is handled under the website privacy policy.