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Author Topic: DCamProf - a new camera profiling tool  (Read 422840 times)

GWGill

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Re: DCamProf - a new camera profiling tool
« Reply #1540 on: May 15, 2017, 10:01:06 AM »

I made a raw image of the Color Checker Passport, opened it in RawTherapee;  Neutral profile.  Cropped the image fairly tightly to just the color patch page of the Color Checker.  Ensure the black patch is positioned at lower right.  In RT Color Management tool: click "Save reference image for profiling"; apply white balance NOT checked.   Resulting image file name: CCPP.tif.

I then proceeded to create a .val file.  This file should contain the RGB values for each of the 24 color patches. First opened a command promp in the folder containing the tif image.

The PROBLEM:  The RGB values shown by the file did not come even close to approximating the reference values for the ColorCheckerPassport derived from several online sources.  Is this to be expected?  If not, where have I gone wrong?

Think about what you are doing. You are taking a picture with the device you are hoping to profile. By definition, the RGB values you get back are in the cameras native colorspace, not some sort of "reference" values. (Any such "reference" RGB values nonsense anyway, the CCP's actual reference values are the spectral reflectances or CIE XYZ values, a CCP target is not an RGB device!).

By being able to correspond the actual colors of the CCP target with the cameras RGB values you can construct a camera profile, which is capable of converting between the camera RGB values and the corresponding CIE XYZ colors.  You can then use that profile to convert camera RGB values into other colorspaces (such as sRGB colorspace, or your displays colorspace), by linking it with the desired destination profile, i.e. Camera RGB -> CIE XYZ -> sRGB. This is the basics of color profiles and color management.
« Last Edit: May 15, 2017, 10:05:02 AM by GWGill »
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mouse

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Re: DCamProf - a new camera profiling tool
« Reply #1541 on: May 15, 2017, 03:35:22 PM »

 
Quote
By definition, the RGB values you get back are in the cameras native colorspace, not some sort of "reference" values. (Any such "reference" RGB values nonsense anyway, the CCP's actual reference values are the spectral reflectances or CIE XYZ values, a CCP target is not an RGB device!).

GWGill:
Many thanks for your reply.  I do understand what you have explained.  I will now carry on and create the camera profile, and see how it comes out.  Thus far I am pleased that I experienced no difficulty using the scanin command and capturing the image with no registration problems.
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1542 on: May 16, 2017, 02:34:19 PM »

Getting closer to release of Lumariver Profile Designer aka DCamProf GUI, here's a quick peek:

https://www.youtube.com/watch?v=UUt3jWs5vTk
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daicehawk

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Re: DCamProf - a new camera profiling tool
« Reply #1543 on: May 16, 2017, 06:40:05 PM »

Getting closer to release of Lumariver Profile Designer aka DCamProf GUI, here's a quick peek:

https://www.youtube.com/watch?v=UUt3jWs5vTk
Any chances to support different targets such as SpyderChekr, Colorchecker 24 etc. and simple matrix profiles tweaked from a zero state by means of Hue, Sat and perhaps a Lightness fader and maintaining a neutral axis? For a LUT profile, I believe the Passport has too few patches and I prefer matrix profiles in general.  What I can see now - there is too many controls and too little data to judge based upon. Anyway, a really good job done.
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1544 on: May 17, 2017, 03:49:48 AM »

Any chances to support different targets such as SpyderChekr, Colorchecker 24 etc. and simple matrix profiles tweaked from a zero state by means of Hue, Sat and perhaps a Lightness fader and maintaining a neutral axis? For a LUT profile, I believe the Passport has too few patches and I prefer matrix profiles in general.  What I can see now - there is too many controls and too little data to judge based upon. Anyway, a really good job done.

There's support for several targets built-in (SpyderChekr 24 is among the supported, not the 48 patch version though, have no data for that), and for the more expensive Repro edition also support for custom targets (then you can scan your 48 patch SpyderChekr), combining multiple targets and even loose patches not in a grid (for spot colors).

I can still guarantee that not all wishes will be fulfilled :-), one thing I've learnt about profiling is that many users have strong opinions on how things should be and they're often contradicting, so one have to choose which users to satisfy. Matrix-only profiles can be made, but it's not the top of the list concerning use case support. Central to the software is still the LUT-based functionality. In fact I don't really think it's that necessary to have a profile maker at all when making a matrix only profile, it's just nine values. It seems like most matrix-only users just want a matrix of those nine values which they can enter by hand. DCamProf command line is more than enough for those hardcore users, so spending lots of time optimizing for that use case when noone will buy it for that anyway seems a bit of a waste.

Concerning patch count I think that relatively few patches like in a CC24 is an advantage for matrix optimization. You just need a few good handles as reference to steer the optimizer. As a matrix is linear it can't do much with lots of patches anyway. There can be an advantage to have many patches to choose from I guess so you can pick exactly the color of the handles you want, but when tuning optimization you only need a few. If you have lots of patches when optimizing the matrix will just lock down to a good average fit and you can't affect it much, which is fine for automatic optimization but not so easy to work with when tuning manually to taste.

For a reproduction I indeed recommend a larger target like CCSG, for which there is built-in support. A large glossy target requires very careful made shooting setup to minimize glare issues though. For a general-purpose LUT profile I think the CC24 is still adequate. The thing is that the LUT should only do very minor adjustments, otherwise smoothness is at risk. The main use of the LUT in a general-purpose profile is to provide the tone reproduction operator, gamut compression and look adjustments, the colorimetric aspect is quite minor. It's even quite common to disable the colorimetric LUT and only use it for the other parts, that is use a matrix-only profile as the base. One can use larger targets though, and multi-target just as with the DCamProf advanced tutorial show, but my experience concerning general-purpose profiles is that it's more a curiosity than a real benefit. Taste may differ there though, and in this case the software does allow for both approaches. Just like DCamProf it's so feature rich that I as the developer can't really predict all use cases users will try. It shall be interesting to see.

Concerning the neutral axis I don't understand what the problem is. Neutral is simply set by the camera's white balance, right? The matrix doesn't affect that, at least not the forward matrix and that's the only matrix that is (optionally) tunable with Lumariver Profile Designer as that is the only thing that matters in 98% of the use cases. Should be said that both DCamProf and Lumariver Profile Designer is "limited" to make only "whitepoint preserving" matrices, that is matrices that don't shift the whitepoint. DNG profiles require such a matrix, but I think it's a general good design property so it cannot be turned off. If you use some other software or just manually enter matrix values you can indeed make matrices that does shift the neutrals away from the white balance setting.

(I still need to do some mundane testing, but it seems quite feasible to make a public release of version 1.0 in 2-3 weeks.)
« Last Edit: May 17, 2017, 05:09:59 AM by torger »
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sebbe

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Re: DCamProf - a new camera profiling tool
« Reply #1545 on: May 18, 2017, 03:40:10 AM »

The video looks very promising. I'm looking forward to the release.
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1546 on: May 22, 2017, 11:10:18 AM »

"DCamProf GUI" the commercial Lumariver Profile Designer 1.0 is now released, see http://www.lumariver.com/#LumariverPD

It's available for MacOS and Windows.
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scyth

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Re: DCamProf - a new camera profiling tool
« Reply #1547 on: May 22, 2017, 03:04:26 PM »

Matrix-only profiles can be made, but it's not the top of the list concerning use case support. Central to the software is still the LUT-based functionality. In fact I don't really think it's that necessary to have a profile maker at all when making a matrix only profile, it's just nine values. It seems like most matrix-only users just want a matrix of those nine values which they can enter by hand. DCamProf command line is more than enough for those hardcore users, so spending lots of time optimizing for that use case when noone will buy it for that anyway seems a bit of a waste.

I have a suggestion which I think was suggested before (may be even by myself) - how about an option to make a LUT profile where LUTs are simply imitating the pure matrix profile (doing nothing really in addition to the matrix transform) but still the tables are  in the profile, but then the user can either take it to Luma* Profile Designer (or to C1 ColorEditor which requires LUT tag A2B0 to be present to work) and do minor tweaks ...
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1548 on: May 23, 2017, 01:25:11 AM »

I have a suggestion which I think was suggested before (may be even by myself) - how about an option to make a LUT profile where LUTs are simply imitating the pure matrix profile (doing nothing really in addition to the matrix transform) but still the tables are  in the profile, but then the user can either take it to Luma* Profile Designer (or to C1 ColorEditor which requires LUT tag A2B0 to be present to work) and do minor tweaks ...

You can sort of do that already, by not making any LUT corrections, but still forcing a LUT to be included by using gamut compression or a tone reproduction operator that requires it, or including a look operator (look adjustments editor in LRPD) that does nothing. Using the latter thing (dummy look operator) I think you can make a LUT that does precisely nothing.

LRPD doesn't have an import function though, that is it cannot import finished DNG or ICC profiles and modify them (except in the inspect/edit tool). Importing a matrix would be a fairly easy feature to add though (importing LUT is harder as the internal LUT format is entirely different from a DCP or ICC LUT)
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scyth

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Re: DCamProf - a new camera profiling tool
« Reply #1549 on: May 23, 2017, 08:04:11 AM »

LRPD doesn't have an import function though, that is it cannot import finished DNG or ICC profiles

how about dcamprof own native ".json" intermediate profiles from "dcamprof make-profile" output ?
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1550 on: May 23, 2017, 08:52:11 AM »

how about dcamprof own native ".json" intermediate profiles from "dcamprof make-profile" output ?

Yes that could be done, I don't think it would be a much used function though, using both DCamProf and LRPD simultaneously, but maybe I'm wrong?
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scyth

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Re: DCamProf - a new camera profiling tool
« Reply #1551 on: May 23, 2017, 09:16:59 AM »

Yes that could be done, I don't think it would be a much used function though, using both DCamProf and LRPD simultaneously, but maybe I'm wrong?

for example if I use SSF then it is faster to create something baseline using dcamprof and then may be I want to tune couple of things visually in GUI ... I think it is logical to provide such a path where GUI product can take over from dcamprof at this point - more so you can write to your own .json profile format whatever support information needed for GUI product ...
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Alexey.Danilchenko

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Re: DCamProf - a new camera profiling tool
« Reply #1552 on: May 24, 2017, 04:17:53 AM »

Well done Anders - it looks great!! I will give it a go alongside the dcamprof

"DCamProf GUI" the commercial Lumariver Profile Designer 1.0 is now released, see http://www.lumariver.com/#LumariverPD

It's available for MacOS and Windows.
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markanini

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Re: DCamProf - a new camera profiling tool
« Reply #1553 on: July 01, 2017, 06:54:04 AM »

Any tips on how I can use a IT8.7 target for a quick-dirty camera profile? I have a xenon flash and shoot through umbrella at my disposal.
« Last Edit: July 01, 2017, 07:00:31 AM by markanini »
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scyth

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Re: DCamProf - a new camera profiling tool
« Reply #1554 on: July 01, 2017, 09:08:28 AM »

Any tips on how I can use a IT8.7 target for a quick-dirty camera profile? I have a xenon flash and shoot through umbrella at my disposal.
if this is from usual source (like Faust) then it is gloss/semi-gloss and extra care shall be taken to avoid reflections  ... you also want to avoid spilling the light all over place so why 'd you use umbrella ? covering everything (sides, top, bottom) in matte black cloth (make some kind of a box inside a room) is a good idea and directing light at angle and lens though holes in that cloth
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torger

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Re: DCamProf - a new camera profiling tool
« Reply #1555 on: July 03, 2017, 02:10:02 AM »

IT8.7 or other (semi-)glossy targets aren't that good for quick-and-dirty profiles as they're so sensitive to glare. You need to really work hard to reduce glare to a minimum to make good use of such a target, otherwise any matte target will be better.

There's some shooting tips here https://www.ludd.ltu.se/~torger/dcamprof.html#shoot_target and here http://www.ludd.ltu.se/~torger/photography/camera-profiling.html#step3 and you can find more if searching the web for reproduction photography tips.
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