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Some RAW converters (like RawTherapee, darkTable and photivo etc.) do support the LAB space in their curve tools and in various other modules. Especially RawTherapee has in my experience here very good LAB support.

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2 hours ago, v_kyr said:

Some RAW converters (like RawTherapee, darkTable and photivo etc.) do support the LAB space in their curve tools and in various other modules. Especially RawTherapee has in my experience here very good LAB support.

 

Thanks.  So you use tools independent of Photo for RAW conversion?  Does that imply Photo doesn't have RAW to LAB conversion or that it is not as full-featured in RAW conversion (yet?) as, for example RawTherapee, at least in terms of LAB?

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My personal workflow for RAW development is different here and optimized to my individual needs, meaning I don't use Photo for RAW conversion and instead a dedicated RAW processor which gives me the best results for the DSLRs I use.

12 hours ago, irascible said:

Does that imply Photo doesn't have RAW to LAB conversion or that it is not as full-featured in RAW conversion (yet?) as, for example RawTherapee, at least in terms of LAB?

One has to differentiate image RAW processing and image manipulation/editing here, APhoto AFAIK doesn't support LAB during RAW processing (aka in the Develop Persona), but it offers LAB support in the Photo Persona. So here after RAW development you can use/switch to LAB mode for further image manipulations in it's general image editing mode. RawTherapee offers LAB during RAW processing.

For example, I once had to do a photo shoot abroad in a strange studio, strange in the sense of the studios lighting system triggering here, which partly had misfires. So I got sometimes also some shots inbetween which were highly overexposed and normally unusable or plain unrecoverable. Later when reviewing and working out the whole material on the computer I also tried to rescue some of those usually unprocessable shots. With RawTherapee and working in LAB mode I was able to recover some of these shots, which weren't recoverable at all with other RAW converters.

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21 hours ago, v_kyr said:

My personal workflow for RAW development is different here and optimized to my individual needs, meaning I don't use Photo for RAW conversion and instead a dedicated RAW processor which gives me the best results for the DSLRs I use.

One has to differentiate image RAW processing and image manipulation/editing here, APhoto AFAIK doesn't support LAB during RAW processing (aka in the Develop Persona), but it offers LAB support in the Photo Persona. So here after RAW development you can use/switch to LAB mode for further image manipulations in it's general image editing mode. RawTherapee offers LAB during RAW processing.

For example, I once had to do a photo shoot abroad in a strange studio, strange in the sense of the studios lighting system triggering here, which partly had misfires. So I got sometimes also some shots inbetween which were highly overexposed and normally unusable or plain unrecoverable. Later when reviewing and working out the whole material on the computer I also tried to rescue some of those usually unprocessable shots. With RawTherapee and working in LAB mode I was able to recover some of these shots, which weren't recoverable at all with other RAW converters.

 

Thanks for example about recovering the over-exposed shots.  What was it about RawTherapee that made those recoverable versus, say, doing RAW development in Affinity and then switching to the LAB space? I think I am missing a key piece of understanding about the relative advantages of a RAW -> LAB versus a RAW -> RGB -> LAB conversion and also, perhaps separately from color space/model, why one application in the class of sophisticated RAW development applications like Photo, RawTherapee, etc. would develop RAW better than another unless, I suppose, one of the applications is better attuned to the RAW format of a particular camera manufacturer you use?

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Some image corrections, which require a lot of time and effort in the usual RGB mode, are a breeze in Lab mode. This is due to the clean separation of brightness and color information in the Lab system. But Lab image editing is often not only faster, but also more accurate than RGB editing, and some things only become possible in Lab.

The difference in RAW -> LAB versus a RAW -> RGB -> LAB is working and having access to the whole sensor data (RAW) here versus an already converted/stripped down data image format. Further in plain RAW you can influence and tweak expoure tolerances, whitebalances etc. much better than afterwards in a converted RGB image format, due to the full data access.

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11 minutes ago, v_kyr said:

Some image corrections, which require a lot of time and effort in the usual RGB mode, are a breeze in Lab mode. This is due to the clean separation of brightness and color information in the Lab system. But Lab image editing is often not only faster, but also more accurate than RGB editing, and some things only become possible in Lab.

The difference in RAW -> LAB versus a RAW -> RGB -> LAB is working and having access to the whole sensor data (RAW) here versus an already converted/stripped down data image format. Further in plain RAW you can influence and tweak expoure tolerances, whitebalances etc. much better than afterwards in a converted RGB image format, due to the full data access.

 

I fully understand everything you wrote here on the advantages of LAB for editing except this part:

 

"The difference in RAW -> LAB versus a RAW -> RGB -> LAB is working and having access to the whole sensor data (RAW) here versus an already converted/stripped down data image format."

 

In my mind this shouldn't make a difference because after we go RAW -> RGB, we can than pass through the profile connection space to go to LAB and although the individual pixel values would be different, the original color and brightness of each pixel should be the same and displayable any application that knows how to render LAB back through the profile connection space to monitor RGB. However, I notice when converting an RGB image to LAB in Photo, the photo does change slightly. 

 

Perhaps this goes to the fuzziness of RGB being a color model and LAB being a color model and color space?  Are you saying that when you go RAW -> RGB, some arbitrary RGB color space (ex: sRGB or Adobe RGB) is going to be assigned?  Since LAB color space is larger, if you had gone RAW -> LAB, you would have colors falling into the entire LAB space from the RAW sensor data.  Admittedly, some of these would be out of gamut for any monitor and definitely outside sRGB and Adobe RGB, but you could still edit them, even if you couldn't see them, and ultimately make your decision on how to force them into a displayable color space after editing?

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You best give it yourself a tryout in order to see if it yields difference for you, when working directly with RAWs in LAB versus a JPG/TIFF image opened in an image processor like APh and then using it there in converted LAB mode. - Take some of your RAW shots (ideally something highly bad overexposed etc. and hard to adjust/restore at all) and then work it out in both a RAW processor with direct LAB support and an image processor like APh with image to LAB conversion mode.

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@irascible, in the Affinity Develop Assistant, is the RAW output format set to 16 or 32 bit?

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16 hours ago, R C-R said:

@irascible, in the Affinity Develop Assistant, is the RAW output format set to 16 or 32 bit?

 

 

Either, but I must take back what I wrote:

 

"However, I notice when converting an RGB image to LAB in Photo, the photo does change slightly."

 

I cannot replicate this.  I thought this had occurred in the Photo Persona with an RGBA/8 sRGB JPG, but I confused repainting flicker with color change.

 

I do notice dramatic color change when developing from RAW and configuring Develop Assistant to apply a Tone Curve, which I expect.

 

However, without Tone Curve, I see that even with RGB (32 bit HDR), Photo assigned the sRGB color space to the image.  If I understand correctly, even with RGB (32 bit HDR), Photo converted RAW sensor data only into colors inside the sRGB gamut.  When I convert to LAB, these colors will be translated through the profile connection space to the CIELAB D50 color space without noticable change. However, any RAW sensor data that could have been translated into colors outside the sRGB gamut, but inside the LAB gamut, will have been lost (shifted into the sRGB gamut).  Correct?

 

I notice Development Persona the ability to assign a profile to the image when it is converted from RAW.  For example, I could assign Adobe RGB instead of sRGB.  To translate a RAW image into a LAB color model and color space without any loss of color information, do I simply need find a profile that represents the CIELAB D50 color space in the RGB color model, have Photo develop the RAW and assign that profile in the RGB color model, and then convert the document to the LAB color model?

 

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41 minutes ago, owenr said:

You could develop the raw file to a 32 bpc RGB image with the ROMM profile, which has an extremely wide gamut, and then convert to LAB mode.

 

 

Thanks.  My research indicates that ROMM is basically ProPhoto RGB; gamut covers almost every reflected color humans could see; only possible weakness in specular reflections.  Oddly, when I use the Develop Persona, if I choose the ROMM Profile, even with the Develop Assistant set to RGB 32 (HDR), Photo assigns the RGBA/16 color model (and ROMM profile) to the image.  Why the 16 instead of the 32?

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Take a look at the German translated to English Wikipedia entry for the LAB color space (Lab-Farbraum explanation which is better than the english one) and tells you the differences, advantages and disadvantages etc. here.

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2 hours ago, owenr said:

 

I'm having no trouble getting 32 bpc with ROMM RGB profile output from Develop in AP 1.6.7.

 

Photo 1.6.4.104 on Windows.  Here's what happens:

 

Open Photo

Open CR2 (To get access to Develop Assistant)

Develop Assistant Enabled

RAW Output Format = RGB (32 bit HDR) (everything else Take no action)

Cancel Develop

Restart Photo (To make sure Develop Assistant change takes)

Profiles Checked, Set To ROMM

Develop

Result: Image Converted To RGBA/16 ROMM:RGB: ISO 22028-2:2013

Close Open File (Don't Save Changes)

Open CR2 Again

Profiles Checked, Set To ROMM

Develop

Result:  Image Converted to RGBA/32 (HDR) - sRGB IE61966-2.1 (Linear)

 

So not only does RAW get converted to RGBA/16 ROMM:RGB on first pass, after that it gets stuck in converting to RGBA/32 sRGB?

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  • 1 year later...

my NEF for me is in SRGB, or Adobe-RGB, in the APN!

(some APN have different raw Nikon D4 is in YcbCr, linear mode )

S for small, I choose adobe RGB, L*a*b* is a large Space

 

In fact,

the only solution, for this RVB linear => L*a*b* we must have this intermediate step (step visible or not ... )

a linear space to l*a*b*  Unlucky no XYZ option in my  APN and in Aph.

OK

I choose a linear profile Romm (prophoto like) or, adobe linear or a icc linear generate by xrite after calibration is better ?

Here  Developp > basic > Profiles the last item below

Developp and after switch to L*a*b*

See 

https://www.youtube.com/watch?v=ERcKNCIhmUg&feature=youtu.be

 

Yess, I see ROMM RGB is define for 8/16 bit…

I think at this time  on one side we have the space Linear, If mode is linear we could applied the transformation

and on  other side colour precision 8 or 16 or 32 bit.

 

 

other link very interesting, see this with APh, if you use L*a*b*, you know the importance of the gray layer Human are

https://en.wikipedia.org/wiki/Middle_gray

The human eye knows better how to distinguish different luminosities than different colors (more technically, it has a better luminance resolution than chrominance).

 

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