Drop a logo or screenshot to make it glow on HDR displays
JPEG or PNG · up to 12 MP · up to 64 MB
HDRLOGO writes an ISO 21496-1 gain map into your file. The areas you choose render brighter than white on an HDR screen while their colour stays exactly where it was. Encoding happens in this browser, in a WebAssembly module — the image is never uploaded.
Your original and the encoded file stay side by side for the whole session.
A gain map is a second, low-resolution layer inside the JPEG. An HDR display multiplies the base image by it and paints the marked areas above white; an SDR display ignores it and shows the base. The colours are identical either way.
The work happens on this device. A 3400 × 3400 file takes roughly 12 s.