Upload the image, draw a box around the old code or mark, upload the new one, and get a PNG back at the exact original size. This is placed by arithmetic rather than redrawn by a model, so the code keeps its module grid and still scans. 1 credit per image.
A code with a plain white margin around it scans more reliably than one baked against artwork.
White space kept between the code and the edge of your box. Most scanners want at least four modules of the code’s own size, which is usually 16–24px on a poster.
The box is applied at the same pixel position and size on every image, so this fits a run of posters that share a layout.
Add the image you are editing first.