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Author Topic: DCamProf - a new camera profiling tool  (Read 767326 times)

AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #620 on: June 20, 2015, 10:33:03 am »

I absolutely agree with Bart's observation that C1 default curve seems to yield overexposed images.
I think that curve files in C1 do carry both curves and exposure correction commands inside .frv files.
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #621 on: June 21, 2015, 11:12:20 am »

And your point here being? I pointed to RPP because it is one of the few converters that does not use RGB of any kind as its internal working space - it uses UPLab. It is quite possible that tonal curve is applied to the L channel there (Iliah can confirm/deny this as I am not entirely sure).

if you are talking about the curve that you select in RPP's UI = "Curve Type : Film-like, L*, Gamma, Colorimetric Gamma" , then it is applied to raw channels post per channel multiplication for WB and before demosaicking... hence before a color transform guided by a "camera profile"
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #622 on: June 21, 2015, 04:21:33 pm »

if you are talking about the curve that you select in RPP's UI = "Curve Type : Film-like, L*, Gamma, Colorimetric Gamma" , then it is applied to raw channels post per channel multiplication for WB and before demosaicking... hence before a color transform guided by a "camera profile"

You absolutely sure it applies before camera profile?
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #623 on: June 21, 2015, 09:31:13 pm »

You absolutely sure it applies before camera profile?
well, I collected a number of quotes from the authors from raw-rpp.l...j......l.com, plus you can select an output to a .tiff w/o applying any color transform and this control is still enabled - so it works before that.
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #624 on: June 22, 2015, 02:53:29 am »

I've worked with reproduction curves now for a while and I think I'm closing in on something that works.

Using faces is unbeatable when it comes to subjectively evaluating color, much easier to see subtle differences there than in other color ranges.

My goal is to make a tone reproduction curve where the contrast itself is a subjective/artistic matter, but hue and saturation is kept perceptually stable, ie the same as with a linear curve. That is you get to subjectively choose a contrast curve, and then color is automatically adapted to match.

The current prototype uses RGB in linear prophoto to calculate luminance change, this is to make the curve "compatible" with RGB tone curves, ie brightness/contrast becomes the same. The actual working space is CIECAM02 JCh though. Hue is kept at the original value, J (lightness) adjusted according to the curve, and C (chroma) is increased as a function of midtone contrast. Using multiplication rather than addition seems to work best for chroma increase, that is more saturated colors get more increase than less saturated colors. Some fine-tuning left to do though, and then implement in DCamProf.

It's a bit scary to do this as one have to trust one's eyes, there's nothing to verify against if the result is "correct" :)

RawTherapee already has this type of curve, "weighted standard" it's called (try it out if you like), it often produces good results but is a bit low on saturation easily noted on skin tones. In the RT team we're looking at adding a new curve with better properties. Not sure my curve will do then as it's a bit slow, at least in my current implementation. We'll see...
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #625 on: June 22, 2015, 03:15:05 am »

well, I collected a number of quotes from the authors from raw-rpp.l...j......l.com, plus you can select an output to a .tiff w/o applying any color transform and this control is still enabled - so it works before that.
I thought that at least for matrix profiles the input needs to be linear.
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #626 on: June 22, 2015, 07:56:19 am »

I thought that at least for matrix profiles the input needs to be linear.
still, AT = http://raw-rpp.livejournal.com/6180.html?thread=105252#t105252
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #627 on: June 22, 2015, 08:36:30 am »

still, AT = http://raw-rpp.livejournal.com/6180.html?thread=105252#t105252
He does not say anything about profile - only demosaic though I can see how that can be implied.
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #628 on: June 22, 2015, 09:52:13 am »

He does not say anything about profile - only demosaic though I can see how that can be implied.
you are not saying that color transform is applied in RPP to vectors like (r, 0, 0, 0) or (0, g1, 0, 0) or (0, 0, b, 0) or (0, 0, 0, g2), are you ? so that is how it is implied and I think I have some more quotes along those lines...
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #629 on: June 22, 2015, 10:36:08 am »

you are not saying that color transform is applied in RPP to vectors like (r, 0, 0, 0) or (0, g1, 0, 0) or (0, 0, b, 0) or (0, 0, 0, g2), are you ? so that is how it is implied and I think I have some more quotes along those lines...


I am saying I don't know and that you are probably right. I'll have a look at it under Hopper a bit later
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Iliah

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Re: DCamProf - a new camera profiling tool
« Reply #630 on: June 22, 2015, 11:30:38 am »

> I thought that at least for matrix profiles the input needs to be linear.

Depends on CMM.
Yes, user-selectable curves are applied before assigning profiles in RPP; and yet another curve is applied after the profile is assigned to compensate for certain ColorSync weakness - except if the selected curve is "colorimetric gamma". Simulation (film) profiles are a different story.
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #631 on: June 22, 2015, 11:39:23 am »

> I thought that at least for matrix profiles the input needs to be linear.

Depends on CMM.
Yes, user-selectable curves are applied before assigning profiles in RPP; and yet another curve is applied after the profile is assigned to compensate for certain ColorSync weakness - except if the selected curve is "colorimetric gamma".
Thanks for confirmation Iliah. I was looking (quite some time ago) at a binary with Hopper but have not dug deep to understand differences bewteen curves applied at various stages. I was not referring to simulation profiles at all (those are quite different beasts even between generation 1 and 2 from what I could see).
« Last Edit: June 22, 2015, 02:41:26 pm by Alexey.Danilchenko »
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #632 on: June 22, 2015, 12:05:56 pm »

yet another curve is applied after the profile is assigned to compensate for certain ColorSync weakness
isn't that increasing some math errors, curve after curve ...
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #633 on: June 22, 2015, 12:10:22 pm »

Thanks for confirmatrion Iliah.
may be they, knowing what is going to happen when ColorSync CMM will apply the trc(s) from some camera profile - which is known at that moment from what user selects, do some pre-compensation in advance to negate Colorsync and then only apply the real curve  8) ...
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Iliah

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Re: DCamProf - a new camera profiling tool
« Reply #634 on: June 22, 2015, 12:55:46 pm »

> isn't that increasing some math errors, curve after curve
We know what we are doing ;)
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #635 on: June 25, 2015, 03:17:15 pm »

Okay now I'm hating Adobe for their DNG profile format :)

Their DNG Profile processor requires that all 3D LUT entries for saturation=0 or value=0 must be 0,1,1 that is no scaling of saturation or value can happen for neutral values. That saturation (and thus hue) cannot be changed is sort of logical, as saturation for neutral gray is zero and since it's scaled with multiplication it can't change from zero.

However, Adobe has taken this a step further meaning that you can't change value of grays either. That is you cannot make a middle gray a little brighter or darker, it stays at 1.0. This is less logical, as it is possible to scale those values with multiplication, and indeed RT's DCP code does it, but not Lightroom and I just checked not the DNG reference code either.

I should have checked this earlier. I've just completed a tone reproduction operator implemented in a LookTable (and as the table applies a curve it must scale neutrals), but it won't work in Lightroom... ***arrgghh***. It should be possible to work around though by combining the use of a curve and a table, but it got a bit messier...
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #636 on: June 26, 2015, 07:49:43 am »

I have now released version 0.8.0.

The big thing in this release is the neutral tone reproduction operator, that is it's now possible to make a profile that has a tone-curve but still retains neutral color. I will probably fine-tune the tone reproduction operator in coming releases, but it won't change that much. The current version has some issues with blue channel clipping that in some cases can cause some transition issues. Thanks to the blue handling blue skies perform much better than typical profiles so I can't just compress the blue channel without doing something smart. We'll see.

Currently you can only apply the neutral tone reproduction operator on DNG profiles, but I intend to add it for ICC profiles eventually. Although the ICC LUT is simpler to work with than the DNG profile LUTs, it's not well-defined which color-space the curve will be applied in or if it's applied in the ICC or separately, so it's quite some effort to get it in there. It's summer here now so programming will be slower, unless the weather is bad.

If you have no idea what I'm talking about or just want to get some further info I suggest reading the new section on tone curves in the manual, it also contain example images so you get an idea of how it looks and what difference it makes: http://www.ludd.ltu.se/~torger/dcamprof.html#tone_curves

Other smaller features I know some will appreciate is that you can set more DCP tags directly from the command line, like baseline exposure offset and copyright string. Go to the home page to get a full list of changes.
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #637 on: June 26, 2015, 09:47:23 am »

0.8.0 build for Windows (mingw = dcamprof.exe + libgomp_64-1.dll + PDF manual / = copy of Torger's web page converted to PDF /) : https://app.box.com/s/97elm0weiiyackz0dopbwk9e6pw04eap
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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #638 on: June 26, 2015, 10:45:39 am »

those who love smooth graphs shall like this one = B53 Blue 3 - it is a black line on the graph



I decided to try to play with that

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AlterEgo

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Re: DCamProf - a new camera profiling tool
« Reply #639 on: July 01, 2015, 02:29:50 pm »

It looks like the instrument needs cleaning, after all.

so _4_ spectrophotometers later (colormunki, i1Pro2, 2 x Spectrolino - I got one more just in case) here goes XRite

Quote
We've been informed that ColorChecker SG charts (January 2014 production date only!) contain a production failure, especially in the black patches (Lightness and Hue shift). These charts can be replaced under warranty (even, if they are out of warranty) via RMA.

Please send us a digital picture of the reverse of your ColorChecker SG target that will show us the production date of your target. The only production date that is affected is January 2014.

no, they are still not willing to share the numbers, but it seems they are willing to exchange the target...
« Last Edit: July 01, 2015, 02:35:52 pm by AlterEgo »
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