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Author Topic: Lumagen HDR Tone Mapping.  (Read 270 times)

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Offline MrPixels

Lumagen HDR Tone Mapping.
« on: Sat May 20, 2017, 11:58:55 AM »
Tone mapping for HDR has recently been activated in the Panasonic DMP-UB900.  Lumagen video processors are offering their version of tone mapping.

Jim recently posted the following on AVS Forum:

We are really close with the HDR Intensity Mapping release. We are finding that more control can help tune the HDR image and we are adding two additional controls in the HDR Intensity Mapping Parameter Menu. So we are adding new controls which is delaying the release slightly. Should be in the next couple days though.

The controls we will have are:

Ratio: Adjust the calculated Source Mastering Level to the Display Maximum Brightness ratio.

Shape: Adjust how rapid or smooth the transition from the nit-for-nit range to the roll off range is.

Clip: Adjust how much clipping (if any) there is near the maximum input range.

Transition: Adjust how much of the input range to try to reproduce "nit-for-nit" verses the source.

Gamma: Adjust the Gamma response. Note that this is a back door to adjust the Gamma_Factor parameter. We thought it good to add it in the HDR parameter menu to simplify changes.

Black: Adjust the Black level. We are finding that reducing the Black level some when using HDR Intensity Mapping improves the image perceived contrast ratio.

There is a HDR Intensity Mapping Parameter menu for each input memory (MEMA to MEMD). So you can setup several mappings and quickly step between them for a visual comparison.

You can also temporarily turn off HDR Intensity Mapping, or show a split-screen with HDR mapping on the right half, for a visual comparison. However, be aware that TVs often change the output brightness based on average picture level of their input. So turning off the HDR mapping, or going split-screen, may not be an apples to apples comparison due to the TV/projector changing its response as a result of the changed levels from the Pro.

There will also be a debug feature. When using HDR Intensity Mapping this feature turns pixels above the programmed linear-Gamma threshold into flashing-red pixels. This is intended as a way to help characterize source levels as we are seeing that the levels in general are not using as much of the source range we we expected. We are making this available to show why virtually nothing gets clipped by Clip and the Shape or Transition are not affecting the image as much as we expected. Note that this also works with SDR but for SDR sources the level is programmed in source Gamma rather than linear Gamma. We reserve the right to remove this feature at any time.

To enable the debug mode enter MENU 0532. You adjust the threshold in percent. You will see that for most scenes there are generally no pixels above 20%, which is generally in the nit-for-nit range where Shape, Clip, and Transition, have little or no effect. There are of course scenes (such as gun muzzle flashes, and explosions in Mad Max Fury Road) that have bright elements that are affected by these controls

Linkback: http://dci-forum.com/d-cinema-home/11/lumagen-hdr-tone-mapping/2026/