Databending in the browser: re-filter the scanlines, corrupt the data, let the broken filters propagate.
…or drop a file anywhere. Nothing is uploaded.
What shows through where the glitch has punched holes in the alpha channel.
The broken filter bytes are written into real IDAT chunks with valid CRCs, so it opens anywhere and stays glitched. Any background other than transparent re-encodes the composited pixels instead — identical to look at, but the corrupt filter bytes are dropped from the file.