Five IR-Blockers Tested for Visible Color Use on Full Spectrum Camera

[photoni]

I would like to ask a question. When I am changing the ICC from sRGB to AdobeRGB, is it better to go all the way back to the raw NEF and work forward through the TIF export and final resized JPG while using AdobeRGB from the start in the raw file? OR, can I simply apply AdobeRGB to the final JPGs as a last step regardless of what ICCs I used along the way? Thanks for any input on this.

 

Raw / Nef, has a large 12/14 bit color table (LAB colors not RGB) without profile, without color temperature.

when you translate it to RGB 8 Bit (Jpeg or Tiff or PSD) you cut information

AdobeRGB / P3 files have more information

sRGB (s = simple) files have little information

you can go from a large table to a small table

You can't switch from sRGB to AdobeRGB, the files will be the same

 

I tried the soft colorChecker once again with the normal Z7, it is a soft that produces too saturated and unbalanced results.

if you are looking for color fidelity, use a specific soft for raw reading. Use Nikon soft, or Photoshop CC or Capture One, or DXOMARK software P.S. switching to DNG also worsens the results.

[photoni]

Compare custom color profiles for filter #2 with sRGB and with AdobeRGB. The differences are minor. I think the change in the pinks is most noticible. To review, #2 == BG38 x 2.00 mm.

 

the first photo (sRGB) is much duller / gray

[photoni]

I think the iPhone screen is good enough photini. I can see all Adobe except some of the blacks on it.

 

iphone from "PRO" model 7 uses monitors with DCI-P3 color profile similar to AdobeRGB but more shifted to red tones

they are expensive smartphones but with better colors than almost any laptop.

[Andy Perrin]

Mine is the iPhone 12 Max Pro and I think it has the best color of any device I own.

[photoni]

Not an answer but some interesting reading here:

https://www.colourma...olour-profiles/

 

perfect !!!

 

it is from photoshop 5 of 1998 (approximately) that we talk about it, but I think 10% have understood it

[Andrea B.]

EDIT: 23 August 2021 12:51 PM Mountain Standard Time

Somewhere in the workflow I lost the AdobeRGB embedded ICC.

I have removed the original posted photos.

The new ones will be up soon.

23 August 2021 12:57 PM Mountain Standard Time

Replacement photos uploaded.

---

 

I reworked the photo of the CC Passport made using the BG38 x 2.00 filter.

 

The first two comparisons show that creating a custom color profile improves color

in both Adobe RGB and sRGB

 

 

sRGB White Balance Only (1st) versus sRGB Corrected Color (2nd)

sRGB color is improved by using a custom color profile.

 

 

 

adobeRGB White Balance Only (1st) versus adobeRGB Corrected Color (2nd)

Adobe RGB color is improved by using a custom color profile.

 

 

 

sRGB Corrected Color (1st) versus adobeRGB Corrected Color (2nd)

[ulf]

Would it be of some interest to see the reflectance spectra for the colour-patches?

 

I am quite choked with work for the moment, but eventually I think I can do those measurements and post the results on the forum.

I believe I have all equipment needed, except a Spectralon reflectance reference target.

A virgin sanded PTFE sheet will have to do as a replacement.

[photoni]

I reworked the photo of the CC Passport made using the BG38 x 2.00 filter.

 

 

once again there is a problem, the 6 files you put # 56 have sRGB color profile !!! ???.

the previous # 47 were perfect, they had a different profile

 

P.S.

On Flickr "Vivek Iyer" recommended me the "Rocolax ICF" filter for UV IR block instead of the Baader, do you know that?

[dabateman]

 

 

 

once again there is a problem, the 6 files you put # 56 have sRGB color profile !!! ???.

the previous # 47 were perfect, they had a different profile

 

P.S.

On Flickr "Vivek Iyer" recommended me the "Rocolax ICF" filter for UV IR block instead of the Baader, do you know that?

 

I have seen that filter, its like a cheap BW 486 filter. I think it lets in UV at 380nm and above.

Similarly to the SvBony UV/IR blocking filter.

[colinbm]

Dave or Toni, do you have a graph of the 'Hot Mirror' of the Sony camera that Toni has please ?

[Andy Perrin]

Would it be of some interest to see the reflectance spectra for the colour-patches?

 

I am quite choked with work for the moment, but eventually I think I can do those measurements and post the results on the forum.

I believe I have all equipment needed, except a Spectralon reflectance reference target.

A virgin sanded PTFE sheet will have to do as a replacement.

Ulf, do not bother, there are already ample spectra available freely online! Including standard deviation between samples. You can download it here:

https://www.babelcolor.com/colorchecker-2.htm#Xxr_v192_CCP2_data

 

What you could do is try verifying one or two squares just to make sure nothing has changed since that data was collected a few years ago.

[Andrea B.]

once again there is a problem, the 6 files you put # 56 have sRGB color profile !!! ???.

 

GEEZ!! My bad.

But I cannot figure out where in the workflow this happened. :wacko:

 

I will try a different approach and post back here when I get it fixed.

 

LATER: The photos were re-posted with the correct aRGB and sRGB.

[Andrea B.]

CC Passport

What you could do is try verifying one or two squares just to make sure nothing has changed since that data was collected a few years ago.

 

A reminder that a few years ago, the patches on the CC Passport were changed. I have the updated version dated 2014.

[Andy Perrin]

Andrea, this is why it would be good to do a check.

 

(I misunderstood the above site and thought they had some post-2014 data also but now I can’t seem to find it.)

[ulf]

Ulf, do not bother, there are already ample spectra available freely online! Including standard deviation between samples. You can download it here: https://www.babelcol..._v192_CCP2_data What you could do is try verifying one or two squares just to make sure nothing has changed since that data was collected a few years ago.

Andy - Thanks for the information.

I did not know that information was available.

 

I might still do some measurements, at least to test if my setup is able enough to generate data for comparing to the data sets.

All of these profiling stuff is normally done in very controlled environments.

A typical viewing light for printed matter do not have much UV-content.

 

There might be some differences for us with modified cameras and/or more UV-rich illumination as from the sun or a modified flash.

 

After much searching I found my reflectance measurement heads.

The one to use here is a small barium sulphate coated integrating sphere.

It has a collimator for the illumination beam and a 90° fiber port for the output.

I designed it for measuring non-specular reflectance a few years ago and have not used it very much.

[dabateman]

This is also a good read. Not just for the command prompt correction tool, but also about targets and the changes.

http://rawtherapee.com/mirror/dcamprof/dcamprof.html#gui

 

[Andrea B.]

Man, Dave! That link contains everything you'd ever want to know about profiling. I could get into that. But I try not to let myself get carried away. Lack of time, primarily. And there's only so far to go with this and no further because anything posted online is viewed on so *many* different monitors (phone, laptop, pc, etc) that ultra-profiling doesn't really make sense.

 

This guy Lindblom was the one who collected all the CC patch data for the ealier versions.

http://www.brucelindbloom.com/

http://www.brucelindbloom.com/ColorCheckerRGB.html

[photoni]

once again there is a problem, the 6 files you put # 56 have sRGB color profile !!! ???.

 

GEEZ!! My bad.

But I cannot figure out where in the workflow this happened. :wacko:

 

I will try a different approach and post back here when I get it fixed.

 

LATER: The photos were re-posted with the correct aRGB and sRGB.

 

to complicate this article on the difficult problem of color "fidelity",

remember there are also other factors that make a solution impossible:

metamerism

the subjective rendering of colors (we are all more or less color blind, my right eye does not see the same colors as the left)

view on monitor in transparency and view on paper by reflection

color temperature (monitor 6500 ° kelvin - home office lighting warm light 2800 ° K)

[ulf]

Then there is the problem of that some of the patches show fluorescence.

As an example, when I illuminate the orange patch (between the blue and brown) with a 405nm pointing laser the visual reflected light is not blue-purple but more orange or red-tinted.

Is this by design?

Is it important for the function of the target?

I assume that the IR response is not that important if a proper BG glass or IR-cut filter is used.

Many of the patches I measured show a higher and rising reflectance into the IR, above 100% compared to a matted PTFE sheet.

[Andrea B.]

Let's be clear about something.

 

I (personally, as Andrea B.) am *not* trying to "perfect" visible color from a full-spectrum conversion. I am only trying to correct the visible color to a minimal standard, to bring it back as best I can to the original color produced before removal of the internal filtration. This is a small goal, but it helps to standardize the output from our full-spec conversions for posting online here at UVP.

 

I am aware of all the many details that go into color fidelity. That is not needed for posting here on UVP. (But, hey, go for it if you are interested!!!) So I am not going to get into temperature of light in which photos are viewed, monitor light & monitor calibration (beyond the basics), color matching needed for printing, color fidelity needed for products in catalogs, color fidelity when developing new lipsticks & eyeshadows. Don't get me wrong -- it is all quite fascinating stuff.

 

Anyway, I have only two conclusions to make about all this:

• It is quite clear that whether using adobeRGB or sRGB to post visible photos from full-spectrum conversions, those photos have better color if we create some kind of color correction profile based on whatever filter or filter stack we have used to make the visible photos.
  

• The BG38 filter seems to be the best one to use for visible photos from a full-spec conversion. After white balance, the colors are improved. With the addition of a color profile, the colors are improved further.
  

**********

 

Buying a BG38 or its equivalent is a minimal expense in order to improve visible color from a full-spec conversion. The color correction profiles involve a lot more expense, so I know not everyone can manage that.

 

**********

Please understand that what I just wrote here is not a criticism, not at all, against anyone who wants to delve further into correcting color for a full-spectrum conversion than I have !! I **fully** support any such efforts and will read them with interest, OK?

((( Maybe start a new topic about that??? )))

[Andrea B.]

Update 26 August 2021

Clarified overall test goal. Added 1st and 2nd Test statements. Improved title.

[Doug A]

Thanks Andrea B. for all the work put into this test. This is a lot of data. Now convinced a clip in filter won't restore a full spectrum camera back to factory colors. I'll just pick up a BG38, and for really picky work use a stock camera.

 

Thanks,

Doug A

[Guest]

Does anyone know what glass brand type is used for the factory Hot Mirror over the Sony camera sensors? Notably the Sony A6000.

[Andrea B.]

This is one of the things we all wish very much we knew about our cameras. Then it would be easy to use that particular glass as an external filter on the lens whenever we wanted to use a converted camera for ordinary visible photos.

 

The internal filtration might be simple BG glass or it might be some proprietary, coated formulation. We just don't know. Manufacturers are not telling. Anyway, they don't expect us to be removing that internal filtration.

[nfoto]

"Anyway, they don't expect us to be removing that internal filtration. "

 

So very true. I'm certainly not the only one having had a camera in for maintenance or repairs to receive it reset to factory order with all the stock filters put back in place.