ClearHDR (imx585)#
ClearHDR is the imx585's on-sensor single-frame HDR.
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Frame rates are lower than the plain modes. Per-mode figures are on the [sensors page].
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CineMate caps ClearHDR ISO, at a different value per depth — 799 in 12-bit and 1585 in 16-bit. See ISO is capped, and not at the same place.
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Auto exposure and auto white balance cannot run in the 16-bit modes (ISP statistics are invalid at 16-bit). Set exposure manually.
Live knobs#
The Clear HDR merge behaviour is tunable while streaming. Each command writes a Redis key that cinepi-raw applies to the sensor as a V4L2 control.
| CLI command | Redis key | Range | What it does | Visual impact |
|---|---|---|---|---|
set hdr threshold low 500 |
hdr_threshold_low |
0–4095 | raw level below which the sensor reads pure HG | lower = earlier hand-off, more highlight headroom, noisier mids; higher = more range stays clean HG |
set hdr threshold high 3000 |
hdr_threshold_high |
0–4095 | raw level above which the sensor reads pure LG | lower = highlight detail kicks in sooner; higher = highlights closer to the plateau before LG takes over |
set hdr blend 2 |
hdr_blend |
0–8 | HG:LG mix inside the transition zone (0 = HG 1/2 + LG 1/2, per the driver menu) | HG-heavy = cleaner transition tones; LG-heavy = highlight detail holds longer through the zone, more grain there |
set hdr gain adder 2 |
hdr_gain_adder |
0–5 | digital gain on the low-gain path in the merge (2 = +12 dB, the driver default); shifts where the blend knee lands in the output range | lower = highlights darker, flatter, cleaner — lift in the grade; higher = brighter highlight rendering, more grain in the highlights |
Known issues#
Flat black-pedestal frames#
A ClearHDR launch can come up with a flat black frame instead exposed image. For the time being, the solution I have found to work is to briefly underexpose the sensor to "kick" it back to normal operation. This can be done by quickly covering the lens with your hand/lens cap or set shutter a 1 and then back.