[Joseph Owens]

[Christian Simpson] “Does Davinci automatically use the most powerful GPU? I should also note that I have the Quadro 4000 in slot 1 and the Radeon card in slot 2. Don’t know if that matters or not. “

No, Resolve doesn’t “automatically” use the most powerful GPU.
Read the configuration guide.

Your ATI 2600 is not approved. In any event, any ATI card (nominally the 5770) should be used for the GUI in slot one and the CUDA/nVidia card (whihc will be used for color processing) should be in slot 2, and should NOT be connected to a monitor.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

[Knut Jansohn] “Have you tried the D65-preset,”

We couldn’t even use the D65 preset on the old BVM-1916 CRTs.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

Thanks, exactly the two guys I expected to have the definitive opinions.
So yes for some things, but no biggie for things like AVID, FCP (not X), or Resolve.

I was really wondering if there were any overhead issues with having both an ATI OpenCL card and nVidia CUDA cards in the same chassis that might be ameliorated.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

Here is a note that was posted to the TIG earlier this month:

Why We Sometimes See Different Colours
Richard Kirk
6th January 2011

Several people have asked me recently why white on two displays of different types – usually a CRT and an OLED monitor – look different even though they have the same CIE XYZ when measured with a spectrometer. Here is my answer for OLEDs and CRTs: the same aruments can probably be applied to other displays.

* Comparing an OLED and a CRT…

The OLED red is a single broad peak, while the CRT red is a complex spectrum with two sharp peaks.

All video monitors used to agree ten years ago because all quality monitors were CRTs with the same primaries. If you went back 30-odd years and found NTSC primaries with the orangey-red phosphor then you might have seen two CRTs with whites that did not match. If digital projectors were the same size as CRTs then we might have noticed the whites did not match five years ago, but they aren’t and nobody did.

Today we have flat-panel monitors which look respectable next to a BVM CRT. We see sharp detail and good shadow tones. The obvious next step is to calibrate the monitors and see how similar they look. We match the monitor whitepoints in XYZ using a spectrometer, but the whites look different. Different people see different shifts. Why?

The only explanation is that the CIE standard observer is not accurate enough to predict what we see.

Can we improve on the 1931 standard observer? This is surprisingly hard to do. The CIE model is based on the assumption that we have three detectors in the eye sensitive to red, green, and blue, a bit like a digital camera mosaic. If two colours give the same signal at these three detectors then they should look the same.

The human eye is not really like a digital camera. We have a central region on the retina that we use for our precision vision, and we move this around to capture detail as we need it. The rest of our peripheral vision is very fuzzy and has a lot of chromatic aberration which our brain filters out. The central region has a yellow spot of dye over the top and no blue detectors underneath. The colour image we ‘see in our head’ is a weird synthesis of the sharp, central, yellow filtered RG image and the surrounding unfiltered RGB image. Different people have different densities and different sizes of yellow spot, and this affects how their brains merge their central and perhipheral vision.

The original researchers back in 1931 knew about this. They did colour matching experiments where you mixed red, green, and blue lights to match a reference colour. The two colours patches were halves of a circle with a dark surround. They saw they got different results with different sizes of circle, so they settled on a 2-degree circle – about a third bigger than your thumbnail at arm’s length – because this gave the most consistent results.

When you look at a white patch the size of a monitor, this is a lot larger than the CIE 2-degree patch, so the colour we see is influenced much more by the peripheral vision. This means we can get the paradoxical situation when we match all the colours throughout an image at the 2-degree level, but are left with an overall sense that the white does not match at a larger scale. The Arri image is particularly good as showing this.

This is not something that can be easily corrected. We can try colour matching experiments with larger circles, but our eyes move with subjects larger than 2 degrees so it is hard to be sure which part of our eyes we are using. There is a CIE 1964 standard 10-degree observer, but it is not a trusted standard. Also, different people see different matches, so one standard will not fit all.

* Can I grade on an OLED display?

The OLED is not the same as the CRT, but that does not make the OLED ‘wrong’ and the CRT ‘right’. Ten years ago we might have said that anyone looking seriously at an image used a CRT, and so a CRT represented the best working practice. Now CRTs are rare in home and grading suites, and the choice is much less obvious.

My advice is to use an OLED monitor or a CRT when grading. Either will work, but do not use both, and certainly do not put them next to each other. The OLED primaries are at least as good as the old CRT ones. The fault that creates the visual difference is not in the CRT or the OLED but because out eyes do not fit the CIE standard observer.

D65 white has a spectral definition: it was based on the spectrum of noonday sun at Rochester. However, most of us only judge whether our display matches to D65 by measuring XYZ and invoking the CIE standard observer. If we compare any display to true D65 white, it would probably not look like a match: true D65 has a lot more deep blues and violets than almost all display and projector whites.

* Why do we not see colour errors on other displays?

This is quite a recent thing. Ten years ago, people would not have expected to get a visual match on different media.

I have not seen a digital projector look as different to a CRT when displaying matched in-gamut colours, though some digital projectors have red spectra very similar to the OLED displays. However, we have always had to tweak the white point when doing butterfly tests, which is a similar error when comparing a digital projector to film. We also see similar differences: we can get almost all the image colours to a good match, but we still have an impression that the overall white point is different, with the film version looking more yellow-green and less bright.

I believe when we have two similar media, such as two flat panel displays or two projections on a screen, we are conscious of small differences in the white point; but when we compare different media such as a CRT and projected film, or a CRT and a digital projector, then our brains register the different sizes and natures of the displays and ignores the small colour difference.

* Should we use something newer than the CIE 1931 observer?

We know our eyes do not fit the assumptions behind the CIE standard observer. At FilmLight, we got fifty people to match the white of an OLED display to a fixed white on a CRT, and measured the whites with a spectrometer. There was a significant scatter to the results: what looked correct for one person looked significantly out for another. This means we cannot fix the CIE for one observer without making it worse for another.

The problem is not that the 1931 standard is 80 years old. The 1931 experiments have been repeated, and you can get more modern versions of the XYZ weights. These new weights are slightly different in the deep violets and reds, but these changes make little difference to the XYZ values of sensible displays with little signal at these wavelengths. The 1931 values are sufficiently good that most people prefer to use the standard values which everyone knows, rather than to use the more modern variants.

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

[Brani Sulek] “What’s the whole point of adding the pulldown and calling it 24P “

Ah, HDV.

The point is that consumers /pro-sumers get to shoot “24” fps “just like the pros”, even though HDV is a Long-GOP format and is only capable of committing to tape at a nominal frame rate of 29.97.

FRC (frame rate conversion) is even worse from HDV, and is why you’re getting a weird framerate from the “guess” setting. HDV also does not flag the AP like DVCProHD does, so that’s why the Panasonic removal tool doesn’t work, either.

Frankly, its a kind of manual task at this point, since you will have to determine what the 2:3 field phase is for every source clip. I use SHAKE when tasked with this thankless assignment, as it allows you to step through fields to identify the redundant ones, and re-establish true progressive frames.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

ATI Radeon 5770 (Mac Version) is okay for User Interface, and probably the Lite version will run okay in OpenCL.
Its not on the top three choices.

You will need to convert the second output from DisplayPort to DVI with an interface plug. Available at your nearest friendly Apple store or wherever, not likely with the card.

https://ca.startech.com/AV/Displayport-Converters/Mini-DisplayPort-to-DVI-Cable-Adapter-Converter~MDP2DVI

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

Had a very similar situation a few years ago for a “green” contest, but Honda supplied a RED Prius for the shoot. It took a couple of weeks of rotoscoping to change it to the legal Honda paint chip colour. Depending on the complexity of the shot… specular highlights, motion, dust, reflections, the tail-lights (which you might recall are also red) the color transform is neither simple nor straightforward to achieve at a cinematic quality level.

Down and dirty? You could try to qualify as much of the car as you can with a node tree (if required) that generates an alpha, then combine that with either a hue vs. hue curve, or an overall hue/phase shift on a parallel node. You may need to generate a travelling matte with a more sophisticated compositing application, because that is what you are doing. Its not, strictly speaking, exclusively a “grading” operation.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

[stig olsen] “mojo dx or nitris?”

Blackmagic Decklink Extreme on my system and Nitris from the Online system.
We do not work with LUTs as this is a straight-through Legal Video workflow, avoiding RGB as much as possible. FX house was working in AE and exporting ProRes4444 which resulted in some LInear/RGB discrepancies but we put a halt to that.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

So the issue would appear to be a serious mismatch in settings in the media handoff. I am working in an AVID-originated project, AVC-HD original, consolidated and transcoded to DNxHD, graded in Resolve, rendered to DNxHD Target mode and sent to Online. We are also exporting plates in Prores for an FX house, which I can re-imbed in the Resolve timeline seamlessly. Some late FX shots have to be re-imbedded in the exported timeline in AVID, but so far no issues. The external FX facility is working with MochaPro and AE, rendering back to ProRes. We occasionally see some incredibly miniscule decoding differences, but for the most part, the whole RGB, Y’CbCr full-scale/Legal Video selection, when correctly configured, works extremely well, no need for conforming adjustments.

jPo

You mean “Old Ben”? Ben Kenobi?

[Joseph Owens]

[stig olsen] “huge gamma-issues, clippes highlights and the black level is liftet.”

Are you measuring any of these values with an outboard scope? I’m willing to bet you’d see some interesting numbers.

jPo

You mean “Old Ben”? Ben Kenobi?