- This topic has 15 replies, 2 voices, and was last updated 6 years, 2 months ago by
.
-
Posts
-
I just picked up a used Sony LMD-2110W and hooked it up to my iMac through a Blackmagic Mini Monitor to HDMI. Reset it to the default settings and was very pleased with the image I was looking at. A tad warm, but actually very close to what I was looking at on the iMac.
I followed the Wiki guide to creating a LUT for Davinci Resolve, several times, and in each case, with the LUT applied, the saturation is very low. I know this rec709 monitor is capable of higher saturation by looking at the default image, so what is happening here? Is the LUT clipping values to fit into a 709 space when they are already derived from 709? I’m just baffled.
Mike
Hi,
what’s your measurement instrument?
I know this rec709 monitor is capable of higher saturation by looking at the default image, so what is happening here?
Default saturation may be too high because the monitor’s native gamut may be larger than Rec. 709. Or, you are used to a higher gamma image than what BT.1886 mandates (effective gamma for BT.1886 is dependent on contrast and usually lower than the nominal 2.4, especially near black).
I am using an xrite smile. And I have used this to calibrate other gui monitors and they have come out satisfactory. Thanks.
And I have used this to calibrate other gui monitors and they have come out satisfactory
With what settings? BT.1886? Gamma 2.2? 2.4?
I used the default settings under the resolve option. I did play around with changing some of the setting for a few of the attempts, but I really don’t know what settings I should change for this set up. I’m guessing my setup is exactly what the resolve setting are meant for: video signal out to a rec709 broadcast monitor.
I followed these instructions to the letter:
https://hub.displaycal.net/wiki/3d-lut-creation-workflow-for-resolve/
But, yes, BT.1186, 2.4
Ok. If you want to equalize the monitors in terms of tone response with BT.1886, you’ll have to equalize contrast. I.e. pick the monitor with the highest black level, and adjust the others to match said black level (same for white level). Alternatively, don’t follow BT.1886, and use gamma 2.2 “relative” with 100% output offset (easier option, as it doesn’t require new measurements, just creating new 3D LUTs from the existing profiles).
I’m not really interested in matching my computer monitor, I just mentioned that in comparison. The broadcast monitor set to default settings without LUT applied through Resolve, looks similar in gamma and saturation to my iMac display. With the LUT applied, desaturated and low contrast. Could this be an issue with gamma and space conversion in the LUT creation. My delta values are good according to the report.
I’m assuming the source color space option in the LUT tab refers to that which is coming from resolve, which I know is 709, 2.4. Do the tone curve settings refer to the source or the output? What about input/output encoding?
The broadcast monitor set to default settings without LUT applied through Resolve, looks similar in gamma and saturation to my iMac display.
The iMac is simulating sRGB, so roughly gamma 2.22. If you want a similar tone characteristic, set 3D LUT tone curve to gamma 2.2 as well (no need to re-measure).
I’m assuming the source color space option in the LUT tab refers to that which is coming from resolve, which I know is 709, 2.4. Do the tone curve settings refer to the source or the output?
Source = target you want, same for tone curve.
What about input/output encoding?
Resolve takes care of correct levels, so the 3D LUT needs to be full range.
Thanks for those answers, they cleared a few things up.
On the gamma settings, this can’t be a matter of 2.2 to 2.4. It’s way off of the broadcast monitor’s saturation without the LUT applied. Like if you cut the saturation by half, and decreased the contrast by half. The monitor is receiving a rec709 video signal and displaying it to SMPTE 274M according to the manual. So, if I understand that right, the image is already within the rec709 space. So, leaving the iMac out of the discussion, if I compare the broadcast monitor with and without the LUT, gamma and saturation are way off.
Ugh, my head hurts. What am I missing? I do appreciate your responses.
Create a compressed archive of the profile files (button next to “Settings”, don’t include 3D LUT) and attach it please.
Oh, Also, would you be able to explain why to use absolute gamma vs. relative? By reading the description, it sounds like relative will adjust a display with some output at black, such as an LCD display. Is that correct?
Oh, Also, would you be able to explain why to use absolute gamma vs. relative?
“Absolute” makes it follow the technical curve (irrespective of black level), meaning the effective gamma will be lower than nominal if the display black level is nonzero. “Relative” makes the 50% input have the same effective gamma as nominal.
My-resolve-LUT-attempt.zip
Looks fine, but I’m pretty sure what you’re seeing is the immense “lightening up” of the near black and also midtone values needed to follow BT.1886, due the high black level of 0.27 cd/m2 (and steep gamma of 2.4) of the Sony. So, switching 3D LUT tone curve to an all output offset, relative gamma 2.2 is very likely to match the iMac better.
Tried outputting 2.2 gamma relative, and we’re getting there. Colors and contrast looked pretty good. But it was noticeably dark on the bottom end. By looking at color bars I can see that the pluge bars are too crushed, where the 4% bar is barely visible, and the 2% is lost. Would you suggest trying to use the option to offset the blacks?
