DCamProf - a new camera profiling tool

[Bip]

If I understood your question correctly [...],

Yes, thank you

[AlterEgo]

I looked at, but it is difficult to do an opinion.

I am for sure way less qualified than Robyn Myers, I just shared my measurements for posterity...

[Bip]

Versions follow and I don't follow ...
Thank you for everything, and for this new guide "Making a camera profile with DCamProf". I have a good read.

I did the dcp profile with the CC digital SG from the ssf datas of the D700, it works great on images, I have the Delta E measures to do when I have the time.

[Frederic_H]

Anders,

How would you design the "make close-to-gray more gray" look ? Something like ScaleChroma < 1 applied to [0,10] chroma range ?

In your experience, is the W Faust C1 IT8.7 saturated enough to use alongside a CC24, or a target printed on glossy paper would be needed ?

Thanks.

[torger]

How would you design the "make close-to-gray more gray" look ? Something like ScaleChroma < 1 applied to [0,10] chroma range ?

In your experience, is the W Faust C1 IT8.7 saturated enough to use alongside a CC24, or a target printed on glossy paper would be needed?

I think the C1 IT8 is glossy enough if I remember correctly, so it's probably a good complement. You can think about that later though, the difference between a CC24 profile only and one strengthened with glossy colors is not big.

Your recipe for making close-to-gray more gray seems fine to me. It takes some trial-and-error to nail down the range and value of course. You'd want to fade out the effect towards higher saturation, using a roundedstep curve is good for that.

(As reported in another thread there's currently a bug in the ICC LUT generator that makes darkest shadows too light and posterized. I'm working on a fix for that.)

[torger]

In this older message:
http://forum.luminous-landscape.com/index.php?topic=100015.msg820035#msg820035
you can see a u'v' chromaticity diagram with IT8 patches plotted compared to the pointer's gamut and adobeRGB. As seen the colors are pretty saturated.

[torger]

Just released v0.9.6, fixed a critical bug in ICC LUT generation that caused bad shadows. It doesn't affect DNG profiles, but ICC profiles which uses the neutral tone reproduction operator.

[Frederic_H]

Great, thanks.

We'll get the IT8.7 this week and shoot all the targets at the same time with the Aptus II-7, IQ260 and A7rII.

[Iliah]

May I suggest changing line 266 in colmath.c to a simple "else"

OS X executable:
http://s3.amazonaws.com/IliahBorg/dcamprof.0.9.6.zip

[AlterEgo]

0.9.6 build for Windows ( mingw = dcamprof.exe + libgomp_64-1.dll + both manual & tutorial / = copies of Torger's web pages / in 3 formats : IE archive .mht, Mozilla archive .maff and regular .pdf ) : https://app.box.com/s/nhqbo5znht2htv0fuwcrh4dxgjdtziby

[torger]

Yet another release, 0.9.7, yet another fix for the ICC LUT. Hopefully I got it right this time, but I can't promise it. This is one of those test for 30 seconds then release... not sure how much time I have next week to code so I just wanted to get something out before I go to bed.

http://www.ludd.ltu.se/~torger/files/dcamprof-0.9.7.tar.bz2

[AlterEgo]

0.9.7 build for Windows ( mingw = dcamprof.exe + libgomp_64-1.dll + both manual & tutorial / = copies of Torger's web pages / in 3 formats : IE archive .mht, Mozilla archive .maff and regular .pdf ) : https://app.box.com/s/1yjsgml85xr1na3m7olkeqsncgsyb2h5

[howardm]

version 0.9.7 statically compiled for MacOSX

https://app.box.com/s/mpf11cs0clolsyb87hjuzzzrjx0e5qv1

[torger]

I'll probably code a bit less on DCamProf for a period.

The next area to look into I think may be the rendering of very high saturation colors, found in for example flowers. I've noted that it's quite typical to get issues with clipping, the blue range often seems to be the most hurt. In theory the raw converter's built-in gamut mapping would handle this, but few raw converters have any gamut mapping at all, and if they have it it's much to simplistic to handle this type of issues well. Commercial bundled profiles generally have gamut mapping built into the profile itself.

Rendering say a deep purple flower with many shades is difficult. If we want the chromaticity to be as accurate as possible we need to pull it towards gamut clipping, and then we lose tonality. An alternative is to desaturate and lighten to "artificially" add tones which otherwise would just clip.

I personally don't shoot these type of subjects much so I need to get to the florist and make some shots so I can investigate this area more.

[Bart_van_der_Wolf]

I'll probably code a bit less on DCamProf for a period.

The next area to look into I think may be the rendering of very high saturation colors, found in for example flowers. I've noted that it's quite typical to get issues with clipping, the blue range often seems to be the most hurt.

Hi Anders,

Yes, although the clipping will often occur after White Balancing, while the Raw data is not clipped. Blue can result in underexposure if some flower Reds and Yellows are very pure, and those Reds and can be pushed into clipping depending on the illuminant's color temperature. RawTherapee allows to scale the yet undemosaiced linear gamma Raw data to prevent such issues, but if instead the profile is supposed to adjust for that, then things will get difficult pretty fast.

In theory the raw converter's built-in gamut mapping would handle this, but few raw converters have any gamut mapping at all, and if they have it it's much to simplistic to handle this type of issues well. Commercial bundled profiles generally have gamut mapping built into the profile itself.

Not optimal, but such is life ...

I personally don't shoot these type of subjects much so I need to get to the florist and make some shots so I can investigate this area more.

I have a nice Yellow/Red Raw example for you, which is just 1/3rd stop below saturation clipping of the Raw data and with extremely deep blue channel data bordering on underexposure clipping. I also have some others, all very saturated flowers. I'll PM you a link, if you can use it exclusively for testing, just let me know. I do understand that you'd want to visually compare the original with its rendered version, but I can't arrange that.

Cheers,
Bart

[torger]

Hi Anders,

Yes, although the clipping will often occur after White Balancing, while the Raw data is not clipped. Blue can result in underexposure if some flower Reds and Yellows are very pure, and those Reds and can be pushed into clipping depending on the illuminant's color temperature. RawTherapee allows to scale the yet undemosaiced linear gamma Raw data to prevent such issues, but if instead the profile is supposed to adjust for that, then things will get difficult pretty fast.

Not optimal, but such is life ...

I have a nice Yellow/Red Raw example for you, which is just 1/3rd stop below saturation clipping of the Raw data and with extremely deep blue channel data bordering on underexposure clipping. I also have some others, all very saturated flowers. I'll PM you a link, if you can use it exclusively for testing, just let me know. I do understand that you'd want to visually compare the original with its rendered version, but I can't arrange that.

You mean you won't send me flowers?

I don't think I need to compare to the originals in the first stage, I just need to get a sense on how the profile behaves compared to others. After that investigation I'll decide if I need to do more work in the area or not. So please do send me a PM with the link.

[AlterEgo]

You mean you won't send me flowers?

does it make any sense to get a petal, make some (many) readings with spectrophotometer (I'd assume putting it on a black non reflective background underneath) and then make a shot to produce a raw ? that will eliminate he says/she says about the color.

[torger]

does it make any sense to get a petal, make some (many) readings with spectrophotometer (I'd assume putting it on a black non reflective background underneath) and then make a shot to produce a raw ? that will eliminate he says/she says about the color.

There's FReD, Floral Reflectance Database too: http://www.reflectance.co.uk/ where you can get spectra for many flowers. In this case I will be more interested in the subjective qualities then the objective match though. I'd like to investigate if there is value in implementing some sort of gamut mapping feature or not.

[AlterEgo]

There's FReD, Floral Reflectance Database too: http://www.reflectance.co.uk/ where you can get spectra for many flowers.

but not the associated raw files with the actual shots of the full petal which is /IMHO/ might better for subjective (with your eyes and converter with profile being tested) evaluation than using that database + spectral data for the camera sensor & illumination...

[Bart_van_der_Wolf]

but not the associated raw files with the actual shots of the full petal which is /IMHO/ might better for subjective (with your eyes and converter with profile being tested) evaluation than using that database + spectral data for the camera sensor & illumination...

I've just sent a couple of file links to Anders, one of which is a WhiBal shot to at least have 'some idea' (although natural light changes between shots) of what neutral is supposed to look like. The angle of the target (as do leafs) will pick up more, or less, sky and ambient reflections. Flower petals, especially in nature are hard to get 'correct' due to light being filtered by overhead foliage, reflections from the soil and other leafy material, some transparency, and semi-specular reflection of the sky that varies by surface angle of the petals. So a large part will be about subjective rendering anyway. Besides, the colors can also not be displayed without display/print gamut limitations anyway, they can be too pure/saturated at certain angles.

I think Anders is looking at the effect that gamut limitations that are designed into the profile, will have on the overall look.

Cheers,
Bart