[jwhn]

ryans patterns or the auto patterns?

Until today, I was always using Ryans patterns against 2020/P3 but its a v slow process hence I tried the auto patterns casted as its a much faster process.

I used Ryan's patterns, also with the Nvidia Shield. I measured some errors between the auto patterns and the shield (probably caused by my laptop) so I tend to use his patterns.

 

[Dominic Chan]

So just to spell it out essentially, the order for HDR is...

brightness, contrast, 2 point grayscale, luminance (adjusting gamma controls on projector), then disable gamma changes, primary and secondary saturations, re-enable gamma changes?

I'm new to HDR calibration myself, but the way I understand zoyd's procedure is that you do not disable the gamma changes prior to adjusting primary and secondary satuations; on the contrary, you should adjust the EOTF to match ST.2084 (the first column in zoyd's tables) as closely as possible, adjust the colours, then re-adjust the tone curve according to the second column (for 1000-nit master) or third column (for 4000-bit master).

 

[zoyd]

correct, adjust first to ST.2084 and use that function as a baseline for color adjustments, as this is the target that all patterns use for HDR10 calibration. After that apply any tone mapping to try and capture additional highlights (at the expense of absolute color accuracy if your adjustments affect diffuse white and below range).

 

[viperlogic]

correct, adjust first to ST.2084 and use that function as a baseline for color adjustments, as this is the target that all patterns use for HDR10 calibration. After that apply any tone mapping to move to try and capture additional highlights (at the expense of absolute color accuracy if your adjustments affect diffuse white and below range).

Dominic, would you mind putting that in Epson 5040 terms? Adjusting the epson gamma controls while checking against the luminance graph is that "adjusting to ST.2084"? If so, what is then tone mapping?

 

[jwhn]

correct, adjust first to ST.2084 and use that function as a baseline for color adjustments, as this is the target that all patterns use for HDR10 calibration. After that apply any tone mapping to try and capture additional highlights (at the expense of absolute color accuracy if your adjustments affect diffuse white and below range).

for the first step, adjusting to 2084, do you mean try to hit the absolute targets, up to 10,000 nits?

 

[seplant]

Quick update, reset my BC profile to defaults, iris off, high lamp, left contrast at 50, brightness to 52, dialled in grayscale (peak of 148 nits), used Dominics method above to dial in luminance, then did my 50/50 sweep and calibration across the 6 colours using auto generated patterns casted via nvidia sheild. When done the picture looked terrible! Most colours blown. Spun up Ryans disk and put a 50/50 red pattern on the screen and it was seen that the colours calibrated using the generated patterns were miles off. Eg ryans 50/50 pattern was landing on the 75! HCFR was set to 2020/P3. Should HCFR (3.4.5.1) be sending the same patterns as Ryans eg when colour space is set to 2020/P3 eg 50 sat free measure and generated patterns is sending a 50/50 or actually is sending a 50/75? I'm thinking the later the way the colours are lining up.

Currently redoing the colours using Ryans disk. While I can dial in the hue and sat using the CIE digram, how will I dial in the 3rd dimension, brightness, as appears HCFR is off showing the delta luminance for that sat?

Thanks for pointing me here from the owner's thread, Viperlogic! I'll try to restate my question here. Are you trying to calibrate HDR using Rec2020 color space in HCFR with the projector set to Bright Cinema color mode? My understanding is that only the Digital Cinema color mode of the 5040/6040 engages the cinema filter to enable the wider color gamut. I would think if you are using the Rec2020 color space in HCFR but then setting the projector to where it can attain only the standard REC 709 color space, it would be impossible to dial in the colors, especially the green. Keep in mind that I'm totally new to calibrating these projectors and using HCFR, so please correct me if I'm wrong.

 

[jwhn]

Thanks for pointing me here from the owner's thread, Viperlogic! I'll try to restate my question here. Are you trying to calibrate HDR using Rec2020 color space in HCFR with the projector set to Bright Cinema color mode? My understanding is that only the Digital Cinema color mode of the 5040/6040 engages the cinema filter to enable the wider color gamut. I would think if you are using the Rec2020 color space in HCFR but then setting the projector to where it can attain only the standard REC 709 color space, it would be impossible to dial in the colors, especially the green. Keep in mind that I'm totally new to calibrating these projectors and using HCFR, so please correct me if I'm wrong.

Check out this post...

http://www.avsforum.com/forum/68-di...ub-6040ub-owners-thread-392.html#post55162546

 

[zoyd]

for the first step, adjusting to 2084, do you mean try to hit the absolute targets, up to 10,000 nits?

Follow the absolute targets up to the point where your projector clips.

Thanks for pointing me here from the owner's thread, Viperlogic! I'll try to restate my question here. Are you trying to calibrate HDR using Rec2020 color space in HCFR with the projector set to Bright Cinema color mode? My understanding is that only the Digital Cinema color mode of the 5040/6040 engages the cinema filter to enable the wider color gamut. I would think if you are using the Rec2020 color space in HCFR but then setting the projector to where it can attain only the standard REC 709 color space, it would be impossible to dial in the colors, especially the green. Keep in mind that I'm totally new to calibrating these projectors and using HCFR, so please correct me if I'm wrong.

That's right, the projector needs to be in Rec2020 mode with largest gamut possible (hopefully that's close to P3 primaries) and HCFR set to BT2020/P3

 

[Dominic Chan]

That's right, the projector needs to be in Rec2020 mode with largest gamut possible (hopefully that's close to P3 primaries) and HCFR set to BT2020/P3

The problem with projectors is that they are very bright for SDR but not so much by HDR standard. If you put them in the widest gamut mode (Digital Cinema) the brightest takes another big hit.
It’s a matter of trade off, common to all projectors when it comes to HDR.

 

[Dominic Chan]

I would think if you are using the Rec2020 color space in HCFR but then setting the projector to where it can attain only the standard REC 709 color space, it would be impossible to dial in the colors, especially the green. Keep in mind that I'm totally new to calibrating these projectors and using HCFR, so please correct me if I'm wrong.

The Cinema and Bright Cinema modes are actually wider than Rec709; Natural is Rec709.
They still can’t hit P3, hence the reason for using 50% or 75% saturation when dialing in the colors.

 

[jwhn]

Follow the absolute targets up to the point where your projector clips.

Okay, and just to make sure I'm tracking, its going to be very tough for projectors to get even close to this, even starting at 20%/30% in my case. So just trying to understand the practical usefulness of this approach.

In the attached graphic, I am pretty much pushing my gamma all the way as it is. As you can see, my poor projector has no chance of following 2084 even starting at 30%.

Is this still the recommended approach?

 

[zoyd]

Okay, and just to make sure I'm tracking, its going to be very tough for projectors to get even close to this, even starting at 20%/30% in my case. So just trying to understand the practical usefulness of this approach.

In the attached graphic, I am pretty much pushing my gamma all the way as it is. As you can see, my poor projector has no chance of following 2084 even starting at 30%.

Is this still the recommended approach?

Looks pretty bleak for accurate color reproduction, although the BT.2084 curve doesn't look right...should be 92 nits at 50% stimulus.

 

[jwhn]

Looks pretty bleak for accurate color reproduction, although the BT.2084 curve doesn't look right...should be 92 nits at 50% stimulus.

Well I was able to get low errors against 2020. And with these settings its the best I've been able to get HDR content to look so far. So there's hope!

And you are right on the graph- it's just my labels off. Should be shifted over one. So 40% is actually 50%.

EDIT: I updated the graph so as to not confuse anyone. ; )

 

[Dominic Chan]

Well I was able to get low errors against 2020. And with these settings its the best I've been able to get HDR content to look so far. So there's hope!

And you are right on the graph- it's just my labels off. Should be shifted over one. So 40% is actually 50%.

To try out zoyd’s approach, you can push the Contrast control up to match ST2084 up to 50%, adjust colors, then re-adjust the EOTF to one of the rounded curves.

 

[jwhn]

To try out zoyd’s approach, you can push the Contrast control up to match ST2084 up to 50%, adjust colors, then re-adjust the EOTF to one of the rounded curves.

Okay, will try that. I did put up the contrast and take down that last gamma setting as you had done. Gets to a similar place but I will keep playing with this.

 

[jwhn]

ryans patterns or the auto patterns?

Until today, I was always using Ryans patterns against 2020/P3 but its a v slow process hence I tried the auto patterns casted as its a much faster process.

One thing to check - are you starting by measuring a grey 50/50 pattern before doing the primary and secondaries?

 

[viperlogic]

One thing to check - are you starting by measuring a grey 50/50 pattern before doing the primary and secondaries?

Will have to check again as can't remember! Changed alot last night!

 

[viperlogic]

I'm new to HDR calibration myself, but the way I understand zoyd's procedure is that you do not disable the gamma changes prior to adjusting primary and secondary satuations; on the contrary, you should adjust the EOTF to match ST.2084 (the first column in zoyd's tables) as closely as possible, adjust the colours, then re-adjust the tone curve according to the second column (for 1000-nit master) or third column (for 4000-bit master).

correct, adjust first to ST.2084 and use that function as a baseline for color adjustments, as this is the target that all patterns use for HDR10 calibration. After that apply any tone mapping to try and capture additional highlights (at the expense of absolute color accuracy if your adjustments affect diffuse white and below range).

Follow the absolute targets up to the point where your projector clips.

This is where I'm getting lost, especially in terms of Epson controls, so please bear with me, is the st.2084 curve the white dotted line in the luminance view? When doing a 11 or 21 grayscale sweep it produces a yellow solid line. What Epson controls should be used to "match" the yellow solid line to the white dotted line, contrast or gamma? When you say match do you actually mean match the shape of it not its actual points?

If Epson gamma controls are being used then isnt that tone mapping and hence the two steps are the same thing of adjusting to ST.2084 and tone mapping?

If contrast is being used then at what should we set contrast to because for me with contrast at 50 up to level 642 flashes. If I want higher levels to flash then I have to reduce contrast eg contrast level 29 causes upto level 712 to flash.

I apologise if these seem"dumb" questions and I keep asking the same thing over but I'm struggling here, and I'm sure others are also.

Using Dominics steps (and contrast at 50 and near same gamma settings on Epson) as our max nits are nearly the same (141 vs 147), I get the following

 

[zoyd]

Yes, technically to calibrate you would set your contrast so that you see no flashing levels above 539 for 140 nits max luminance and adjust your 10 or 20 pt controls (if you have them) to match the shape of the white dotted line. The material was mastered to this line. If you can't clip at 539 then I would get 50% (502) as close to 92 nits as possible. Then you would adjust your color controls using patterns that are designed for 50% levels (92 nits). At that point you would back off on contrast and use 10/20 point controls to match one of modified curves (what we've been calling tone mapping), to bring back some of the highlights.

 

[viperlogic]

Yes, technically to calibrate you would set your contrast so that you see no flashing levels above 539 for 140 nits max luminance and adjust your 10 or 20 pt controls (if you have them) to match the shape of the white dotted line. The material was mastered to this line. If you can't clip at 539 then I would get 50% (502) as close to 92 nits as possible. Then you would adjust your color controls using patterns that are designed for 50% levels (92 nits). At that point you would back off on contrast and use 10/20 point controls to match one of modified curves (what we've been calling tone mapping), to bring back some of the highlights.

Unfortunately with the Epson 5040 we are very limited in our controls, we only have two point control of offset and gain for RGB. For gamma we have 9, known as colour tone 1-9. Then for colour we have hue, sat, and brightness for each of the RGBCYM colours