GH5 GH5 to Alexa Conversion

Sage,

Any chance you’d work up another LUT for 4500k? Going to test your other two soon, but often shoot at 4500k, especially in mixed light scenarios.
 
Bern Caughey said:
Sage,

Any chance you’d work up another LUT for 4500k? Going to test your other two soon, but often shoot at 4500k, especially in mixed light scenarios.
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Thomas Smet said:
4500k is also nice if you use color adjustable LED lights and want the higher output of using both sets of colors.
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This is something I am working on; its involved. At the moment, the Tungsten & Daylight versions may be used to good effect.

There are two things which combine to result in a color science output; these are the sensor response and the interaction between white balance and color space. In the case of sensor response, this is the wavelengths of light that the RGB photosite dyes allow in to constitute red, green, and blue, and how the pipeline interprets and sums this base signal. Because of this, different sensors will 'see' different results in the same light source. While daylight and tungsten are highly predictable, leds and flourescents are highly variable in their exact wavelength distribution. For a fully accurate conversion, one must be made for each distinct light source. Each new conversion is work intensive. In the case of white balance interacting with color space, each profile - and each white balance of that profile - will differ in the same camera with the same light source. All of these moving parts constitute a fully complex system with a predictable result given fixed conditions. I am working on ideas to tackle this (a conversion for each fluorescent tube, each led dial setting, etc. would not be practical).
 
Hybrid Log-Gamma

Hybrid Log-Gamma

Hybrid Log-Gamma Support Added

Hybrid Log-Gamma (HLG) conversion variations are now included with each light source, in addition to the V-Log variations. They are indistinguishable from the V-Log variations. Also, the V-Log variations have been updated.
The documentation PDF will be updated to reflect the new HLG support on Friday.

Attached is the first in a series of comparisons that will demonstrate the difference between native GH5 color science and Alexa color science. For the conversion image, only the main GHa Daylight conversion has been applied, with no other alteration. The native color image has been matched in contrast and saturation using the Lift-Gamma-Gain controls and saturation slider.

daycomp.gif


daycomp2.gif
 
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Thomas is exactly right. It is why I use the 4500k with my Ikan Lyra soft lights, because it utilizes all the LED's to maximize the output.
 
Have a series of dual camera interviews against a painted canvas today. Using a SkyPanel S60-C with Chimera, & set the CT to 5600k. Luckily we have a great DIT, & am going to ask him to test the updated GHa Daylight LUT.
 
rob norton said:
Nice video sage, what support did you use for the movement?
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In '08 I started practicing a technique that uses a tripod as a stabilizer that would allow shots not possible with conventional means. To this day, I use that technique, and prefer light, tiny cameras for this reason. Also, there were some handheld shots, which took the place of my old shoulder rig, because the GH5 IBIS has made that possible.
 
video652 said:
Thomas is exactly right. It is why I use the 4500k with my Ikan Lyra soft lights, because it utilizes all the LED's to maximize the output.
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Also, there is added benefit to averaging out the color spikes in the spectrum of the blue and yellow leds

Bern Caughey said:
Have a series of dual camera interviews against a painted canvas today. Using a SkyPanel S60-C with Chimera, & set the CT to 5600k. Luckily we have a great DIT, & am going to ask him to test the updated GHa Daylight LUT.
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Love to see the results. The SkyPanel in particular is quite a nice led with a more balanced color spectrum
 
The PDF has been updated to reflect HLG support, as well as an important detail about luminance levels (P3), brought to my attention by Ryan Glover

PDF

tuncomp.gif

GHa Tungsten Main / Native V-Log Color Comparison
 
In both of those GIF images see a magenta shift on skin tones with my calibrated NEC PA272W.
 
There is indeed a magenta shift in skin tones with Alexa color science. The GH5 color science is decidedly green; reds are toward orange, yellows are greener, and green is deeper
 
Believe the data levels skewed my initial tests of the GHa LUTs, as the GH5(s) were set to Legal, & we recorded ProRes HQ externally.

If possible it be good to have GHa versions designed for Legal Range to avoid confusion when handing off raw footage, especially ProRes, which (with the exception of 444) is never recorded Full Range.

Have an out-of-town gig next week which may be filmed on Alexa(s), & if so hope to test the GHa LUT in a side-by-side.
 
Bern Caughey said:
If possible it be good to have GHa versions designed for Legal Range to avoid confusion when handing off raw footage, especially ProRes, which (with the exception of 444) is never recorded Full Range.
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That's a good idea. I'll issue a [PRE] file which can be used in tandem with the V-Log conversions.

joe12south said:
I hope so, or else the LUT is a waste of money! It is to be compared to Alexa color science, not lab standards.
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Indeed; it deviates from true color to what Arri felt was an ideal image (guided by subtractive film)

brdplya1 said:
I purchased your LUT and used on GH5 log footage this weekend...very impressed!
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Thank you! Send me some shots, I love to see how people use it
 
Bern Caughey said:
If possible it be good to have GHa versions designed for Legal Range to avoid confusion when handing off raw footage, especially ProRes, which (with the exception of 444) is never recorded Full Range.
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Bern, I just sent out the [PRE] file via email. The ProRes situation arose from V-Log L natively having the 'Full' levels flag to conform to the V-Log standard, which is unexpected for a video codec.
 
Hello Alex,

I just purchased the luts and am a bit confused if I am doing something wrong...I shot in HLG and when I apply your lut, the image is excessively over saturated...am I supposed to tweak the image further by hand? I didnt shoot under straight tungsten light or daylight. They were fluorescents at roughly 4400-4600. I know you said the image would have a lot of saturation, but I thought the idea was for your lut to give a useable rec 709 image that looked alexa-like just from applying the lut?

Any help would be greatly appreciated.
 
jeremydulac said:
Hello Alex,

I just purchased the luts and am a bit confused if I am doing something wrong...I shot in HLG and when I apply your lut, the image is excessively over saturated...am I supposed to tweak the image further by hand? I didnt shoot under straight tungsten light or daylight. They were fluorescents at roughly 4400-4600. I know you said the image would have a lot of saturation, but I thought the idea was for your lut to give a useable rec 709 image that looked alexa-like just from applying the lut?

Any help would be greatly appreciated.
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Sure; did you use the HLG version? Was it Soft or Main? And Tungsten or Daylight?

There should be considerably more saturation with GHa than Hlg has natively, but never non-legal or extreme saturation.
 
Interesting. I used the hlg version main. I tried both tungsten and daylight and both seem pretty heavily saturated. Maybe it is just my preference on saturation is different so it seems like a lot. Here is a before and after sample. Any tips for further adjustment after your lut?HLGBefore_1.18.2.jpgHLGwithLut_1.18.1.jpg
 
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