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Author Topic: trouble with contrast, blacks, grays etc.  (Read 7868 times)

elymarques

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trouble with contrast, blacks, grays etc.
« on: October 02, 2013, 03:59:06 PM »
Hello guys. I'm starting to better understand the workflow for creating the DCP. But I am suffering a lot with the issue of brightness and contrast, when I convert to XYZ, where blacks are washed gray. Very unlike finalization original RGB (using a display reference, waveforms, vetorscoopes etc.).

Someone goes through the same type of problem?

my current workflow is: offline edit in FCP, export the EDL's time line for the Apple Color, replace the files by original R3D 4k, where I am re-scaling 2k flat. RED tab, working with REDgamma3 Gamma, Color Space REDcolor3 and the ISO variable according to the take. In the preferred use 32bit Floating Point and projet setings, in the render file type to use Quicktime codec quicktime export apple prores444. XML care for AfterEffects, make some adjustments in composition and apply the "convert color profile" with the input profile: project working space and the output profile DCDM X'Y'Z '(gamma 2.6) 5900k (by Adobe) to Linearize output profile unchecked. in relative colorimetric intent and use black point compensation checked, scene-ref. compensation profile in use project setting. When I go to render, I set up setings in 16bits and the output module in the JPEG 2000 format using the plugin for j2k Lossy marked with 2k digital theater, with data rate of 234 mb per second and trillions of colors in depth.

When I'm with a sequence of JPEG2000 openDCP ready to go and create the xml and then in the MXF folder structure for the DCP.

Well detailed workflow is this, I believe it is really something in the matter of gamma, contrast of the movie is all ok except the parts where the film is darker, black is washed, granular and gray.

The projection test I'm doing is on a server doremi DCP 2000 and Barco Projector DP2K, also used for 3D projections with that disc for this purpose.

some frames and screens of the workflow
https://drive.google.com/folderview?id=0B77ximgszE0tSGRNcWFTMUx1ZDA&usp=sharing

Muhamad Taufiq

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Re: trouble with contrast, blacks, grays etc.
« Reply #1 on: October 03, 2013, 01:45:40 AM »
Are you sure it was 'washed gray' or it was true black but with the projector's limited contrast ratio?

mytbyte

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Re: trouble with contrast, blacks, grays etc.
« Reply #2 on: October 04, 2013, 02:29:40 PM »
@elymarkues:

I had a very similar problem with a Barco projector and a DCP produced using Adobe's DCDM XYZ and j2k by fnord (I think the showplayer was a Doremi)...the projector was not calibrated and therefore was too bright, but even after reducing the lamp brightness to 50% picture still lacked black level performance...another DCP made in the same way looked great in a calibrated commercial cinema...

as I understood it, Adobe's approach to XYZ conversion takes the perceptive approach into account and compensates for the characteritrics of real-life lamps which cannot achieve true 5900K and, I suspect, perhaps also for the low calibrated brightness as per  DCI guidelines of 14 ft/l or 48 cd/m2 and the effect it has to human perception in dark cinema environment...so are you sure the projector was calibrated and fit for the venue? I suspect, in my case, it may have been the combination of ligthspill from (too) strong a lamp on black parts of the image and Adobe's brightness compensation...

however, if it is not that, I didn't quite catch what you are importing into After Effects...is it Apple ProRes 444 (so it should be Rec709)? In that case there shouldn't be such a great loss od black level although you didn't use color management and consequently there is no project colorspace specified for the color Converter effect to use...unless you imported cineon/DPX or a file sequence which has gamma different than 2,2 (say EXR or any LOG file) - in that case this could be the source of the problem...I'd still try setting the color management to Rec.709 and re-do the export...apart for that, I'd use fnord's DCI converter with the gamma set to 2,2 and no chromatic adaptaton...

I myself am not really sure what color profile converter does when it operates in an unmanaged environment (AE color management turned off) since it expects to convert from project's colorspace which is non existent i.e. not specified...

elymarques

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Re: trouble with contrast, blacks, grays etc.
« Reply #3 on: October 05, 2013, 06:31:22 PM »
I resolved the issue as follows :

First of all , I realized that all of the options used in the "color space" ness project , two are identical , " none " and sRGB , understand how the AE automatically identifies the "color space" used by each file , but in the case using multi formats is when you need to choose a current standard .

When in doubt kept the color space to sRGB and applied the " Convert Color Profile " where the "output profile" was selected " DCDM XYZ " , and the " holy grail " was to add the effect of " brightness and contrast " with brightness in " - 12 " and " contrast +6 " . That way I can keep the exact same black level that was in reference before converting to XYZ .

I ran the test in the theater and saw the perfect result of what was before the previsualizado colorgranding .

The question that is still in the air , is the " why ? " this happened , I believe it is a question between the standard " RED- RAW " > AppleProRes444 > XYZ conversion "

 I made a new test in AEFX, created a solid gray, R = 0.15 G = 0.15 B = 0.15. comp and placed in a color space with none applying the solid color profile to convert XYZ output to the effect washed repeats the same manner as previously ProRes444 files. I applied the effect of brightness and contrast to -13 and +6 and got the result very close to the black original black solid.

Does that make any sense?

mytbyte

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Re: trouble with contrast, blacks, grays etc.
« Reply #4 on: October 06, 2013, 01:17:28 AM »
It does make sense if indeed Adobe tried to compensate for the real-life situations (I also find their approach a bit too red/warm when compared in EasyDCP)..also, if instead you choose to use fnord's DCIConverter http://fnordware.blogspot.com/2013/01/dci-converter.html that works directly on your footage (no color management), the default settings seem to produce the same result as Adobe's, unless you strictly specify the 2.2 gamma as input and use no color adaptation instead of default 5900K...

can you try DCIConverter directly on your ProRes? Get back to us with your view of results in theatre...

I also tried it with color management set to Universal Camera Printing Density so that I could work in a common colorspace, and used Color Profile Converter on precomped final to convert it to PhotoRGB with Perceptual intent and then applied DCI Converter with gamma set to PhotoRGB and color adaptation set to D65 and got almost perfect result (gamma was almost unnoticably off - perhaps result of too many colorspace conversions)
« Last Edit: October 06, 2013, 01:35:16 AM by mytbyte »

actpower

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Re: trouble with contrast, blacks, grays etc.
« Reply #5 on: October 06, 2013, 08:57:31 AM »
Is a fact that he XYZ color conversion of Adobe is bad. I have tested a lot over this and their formula isnĀ“t correct.

As always, I have tested over your files, and when tried to make a DCP from the J2C you provided, there is a shift in the blacks, making it brighter.

If I use the TIFF provided by you and converting to J2K myself, the J2K by me is deeper black. So the later XYZ to RGB conversion is the same as the original file as results.

I attach here YOUR J2C file and MY J2C file (in a same screen, left is yours, right is mine), wich looks really different:



Uploaded with ImageShack.us

This is under Premiere, using the DCI color converter from the author the useful J2C export plugin (http://www.fnordware.com/j2k/)  and using my own parameters to match exactly the same color conversion that does EasyDCP, openDCP and others.

I do not recommend  use the Adobe's DCDM XYZ color converter, but is in your hand, of course ;-)



elymarques

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Re: trouble with contrast, blacks, grays etc.
« Reply #6 on: October 06, 2013, 09:00:42 PM »
ok, now using the "DCI convert" (the fnord http://fnordware.blogspot.com.br/2013/01/dci-converter.html) with the "response curve of Gamma at 2.6, I can get the result closer look at when the reference AppleColor.




thank you very much, guys
« Last Edit: October 06, 2013, 09:06:11 PM by elymarques »

mytbyte

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Re: trouble with contrast, blacks, grays etc.
« Reply #7 on: October 07, 2013, 02:16:02 AM »
Pretty weird that you must use 2.6 gamma for response curve ...this would mean that your footage is already DCI gamma encoded or you are using color management set to DCDM XYZ...you are not supposed to use it with DCI Coverter...but ok if it works for you...

actpower

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Re: trouble with contrast, blacks, grays etc.
« Reply #8 on: October 07, 2013, 03:25:26 AM »
Hum, bad idea to up the gamma to those levels, yes...

elymarques

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Re: trouble with contrast, blacks, grays etc.
« Reply #9 on: October 07, 2013, 10:23:08 AM »
Remembering that this original files are Red RAW REDgamma3, REDcolor3. Rendering in floating point for ProRes444 working in AppleColor. This setting tells us something?

mytbyte

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Re: trouble with contrast, blacks, grays etc.
« Reply #10 on: October 08, 2013, 05:54:51 AM »
not much, at least to me, since I'm not familiar with AppleColor and don't use macs...I thought ProRes 4444 is gamma encodec to meet Rec709 spec...

a quick Google search returns some people moaning about ProRes giving different results from Adobe products and even RedCine... ???
« Last Edit: October 08, 2013, 06:03:50 AM by mytbyte »

dcinemaforum.com

Re: trouble with contrast, blacks, grays etc.
« Reply #10 on: October 08, 2013, 05:54:51 AM »