How to use it
- Upload the image.
- Choose the base brightness. Brighter presets lift ordinary white and open up the shadows; highlights stay within what the screen can show.
- Download the MP4 and check it on an HDR display.
What it looks like on an HDR screen
Simulated. On the screen you are reading this on, both halves are identical — an ordinary display has no extra brightness to give. This is how the difference reads on an HDR display.
What the converter actually builds
Both images above are real output from this converter, not an illustration. White areas of the gain map are the ones an HDR screen brightens; black areas stay exactly as they were.
Frequently asked questions
Why choose a base brightness?
PQ video defines absolute brightness, so a straight conversion leaves most of a photo close to black. Each preset sets how bright ordinary white is and how far the shadows are lifted. The darkest keeps the 203-nit broadcast reference from ITU-R BT.2408; the default is brighter, because at 203 nits most of a typical photo sits below 20 nits and reads as dull on a phone.
What comes out?
HEVC Main 10 in MP4, 10-bit 4:2:0, tagged with Rec.2020 primaries, SMPTE ST 2084 transfer and non-constant luminance matrix, plus mastering display and content light level metadata.
Can I just tag an SDR file as HDR instead?
No. PQ code values mean absolute luminance, so tagging without converting gives a wrong picture, usually far too bright and washed out.
How long is the clip?
Two seconds. Every frame is identical, so it loops with no visible seam and the file stays under a hundred kilobytes.