SDR to HDR
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Convert archival footage to HDR

Archival footage carries constraints from its original format that HDR conversion cannot undo: limited capture range, heavy chroma subsampling, interlacing, and generation loss. Converting produces a real 10-bit HDR10 file, but the highlight information the tape or disc never held does not come back.

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What "archival" usually means technically

Tape captures, DVD rips and early digital camcorder footage share a set of properties, and each one limits what conversion can achieve:

PropertyTypical valueConsequence
Bit depth8-bitBanding may already be present
Chroma4:2:0 or 4:1:1Colour detail already discarded at capture
ScanOften interlacedNeeds deinterlacing before anything else
RangeLimited by the acquisition formatNo highlight information above diffuse white

Standard-definition sources add one more: they were mastered against ITU-R BT.601 rather than BT.709, so the colour primaries differ and need converting before anything else is meaningful.

The last row is the one that matters most. Analogue and early digital formats were built around a display standard whose ceiling was diffuse white, and the recording chain clipped anything above it. That information was gone before the file existed.

What conversion does help with

Two things, and they are real.

Remapping into a wider space at 10-bit means the tonal range that is present gets more levels to occupy, so the midtones and the gentle falloff in what highlights survive can render more smoothly than they do in the 8-bit original.

And where the original footage was merely compressed rather than clipped, bright surfaces separate from diffuse white instead of sitting flat against it.

Deinterlace first

If the source is interlaced, deinterlace before converting. Feeding interlaced frames to any process that works on progressive images gives combing artefacts that then get baked into the output. Nothing downstream fixes this.

Setting expectations

Archival material is the source where the gap between "produces a valid HDR10 file" and "looks dramatically better" is widest. The output will be genuine HDR10. Whether it is worth doing depends on whether the original had any highlight range to recover, and for most tape-era footage the honest answer is: some, but not much.

Questions people ask

Is it worth converting VHS or tape captures?

Honestly, marginally. Tape-era formats clipped anything above diffuse white at acquisition, so there is little highlight range to recover, and the result is a valid HDR10 file that looks much like the source. Convert one clip before committing to an archive.

Do I need to deinterlace first?

Yes, if the source is interlaced, and before anything else. Feeding interlaced frames to a process that assumes progressive images bakes combing artefacts into the output, and nothing downstream removes them.

Related: what conversion can and cannot do.

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