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Patrick Gauthier
15-Jun-2016, 21:02
Hi LFF!

I shoot 4x5 B&W and by various means scan my negatives and post-process with lightroom/photoshop. My scans are RAW files and are quite large (~170 mp). About 99% of the time I can convert these while still preserving the digital editing I have done. However, when I have a particular dark and contrasty scene (especially a lot of micro contrast), the conversion cannot handle the dark tones and I'm left with something 'blander' than the RAW file.

Does anyone else work with RAW scans and encounter similar issues? Are my expectations too high?

LEFT IMAGE: lightroom develop module (RAW)
RIGHT IMAGE: Exported jpeg 100% quality in photoproRGB

You can clearly see the differences in the shadows and blacks on the rockwall. The difference is more striking on actual quality files.

151829

Patrick

Kirk Gittings
15-Jun-2016, 21:09
I can't really see the difference on my laptop, which is all I have with me. I have been printing B&W for over ten years now from scanned negs and always work with just Tiffs or the large file PS format. I have never felt that I lost anything by not working in raw format even though I push and pull the tones all over the place.

Peter De Smidt
15-Jun-2016, 21:33
Is this really a raw file, like a file from a Nikon or Canon dslr? I doubt that is the case. By chance, is it from Vuescan? My understanding is these are simply tiffs that save all of the non-software adjustments so that they can be reprocessed by vuescan down the road. Moving on to your color space, do you mean prophotoRGB? If so, why are you using such a huge color space for a black and white image?

Patrick Gauthier
15-Jun-2016, 21:35
Hi Kirk,

A rare situation where working with RAW files may be worse. You may have led me to a solution: exporting un-processed RAW files as .tiff and then directly post-processing the .tiff. With the current image, I may be able to just save the processing adjustments and quickly apply them to the .tiff.

I also occasionally handle .tiff files for processing, this happens when my scans exceed the maximum file size for the photoshop raw .psd format, but typically prefer to work with the raw files because of a speedier workflow.

I will re-post when I try the direct .tiff editing on this particular image tomorrow.

Thanks!

Patrick

Kirk Gittings
15-Jun-2016, 21:46
IME A raw format for raw conversion only offers some benefit when the b&w image is a conversion from a color original. Otherwise the quality of a the scan is a much more important factor such as a drum scan vs. a consumer flatbed.

maxotics
16-Jun-2016, 04:19
Keep in mind you can't really view a RAW file. It has 12 to 14-bits at each pixel location (RGB) and your monitor can show only 8-bits. So somewhere blacks must be pegged to start in an 8-bit space otherwise the RAW would just average to gray (which is how RAW video looks). Or put another way, I don't think it's a problem with your RAW file, it's how your Lightroom Develop module is configured to interpolate the large dataspace of your image down to something your monitor can display and you can see. You can't really look at RAW, sort of like you can't see infra-red.

A good test for you to do is to open the RAW file in the RAW filter and adjust it to your liking, then save as JPEG, then do the same to the JPEG. If there is not difference, use JPEG. If you can get a better tonality with RAW, keep using raw.

Patrick Gauthier
16-Jun-2016, 04:38
Hi Peter


Is this really a raw file, like a file from a Nikon or Canon dslr? I doubt that is the case.

Yes they are true raw, I scan and stitch with a mirrorless camera (sony nex).


Moving on to your color space, do you mean prophotoRGB? If so, why are you using such a huge color space for a black and white image?

I only have three options in exporting from lightroom/photoshop, I normally export with sRGB, but tried prophotoRGB to see if it was any better.

Lachlan 717
16-Jun-2016, 05:00
Given there is no specific ".raw" format (it's a grouped nomenclature of many sub formats), perhaps you are using an unrecognised or partially recognised sub-format.

Why not just use .tiff with properly scanned (unclipped) settings? Given it's lossless/uncompressed, you won't be losing data.

Christopher Barrett
16-Jun-2016, 05:12
Ahh... I think you were causing some confusion by saying RAW scans. You can't get raw files from scanners. Even the Hasselblad .FFFs are actually tifs. Now, digital captures... that's a whole other ball game. Have you tried using Capture One Pro? I use it exclusively for my commercial workflow and greatly prefer the file quality versus Lightroom.

Like Kirk, I don't really see any shadow detail difference in your screen captures, but I'll take your word for it. I'm not sure why you're working with Jpegs, though. Even at 100%, they're still compressed files, so I'm not surprised at all that the algorithm is throwing out shadow detail.

Lastly, I've never had much success "scanning" negs with a digital camera, and this was using a 60megapixel Phase One back... well at least when compared to my drum scanner. But if you're seeing what you want in the RAWS, there is absolutely no reason you can't output that to a 16bit Tiff, which is what I would print from.

IMHO,
CB

Peter De Smidt
16-Jun-2016, 06:33
Hi Peter

Yes they are true raw, I scan and stitch with a mirrorless camera (sony nex).
I only have three options in exporting from lightroom/photoshop, I normally export with sRGB, but tried prophotoRGB to see if it was any better.

Ok. So you get the image how you like it in Lightroom, but when it's exported to Photoshop it's changed? Is that right?

Pro Photo RGB is a huge color space. About 13% of it's colors are imaginary colors that aren't visible. It's a great space if your image has some really saturated colors, but a bw photo doesn't have any. Pro Photo RGB's gamma is also 1.8, unlike sRGB's and Adobe 1998's 2.2. Either of those would be a better choice for your output space.

Speaking of color spaces, what's your working/editing color space in Photoshop? If there are some conversions between spaces happening they could cause a visual difference in the image.

Patrick Gauthier
16-Jun-2016, 07:38
Thanks for all the input!


Ahh... I think you were causing some confusion by saying RAW scans. You can't get raw files from scanners.

Yes fair enough, It's the only way I "scan" so I'm used to using that word to describe my use of a digital camera to digitize my negs.


Have you tried using Capture One Pro? I use it exclusively for my commercial workflow and greatly prefer the file quality versus Lightroom.

No I haven't tried. To be honest, this is only an issue about 1% of the time when I have a lot of shadow detail and contrast mixed in the shadows (e.g., such as for deep rock striations along a mountain side). The rest of the time lightroom and the raw workflow is great. I typically work with RAW because it's quicker in LR, and I ultimately export to JPEG only to reduce file size and for compatibility with flickr and sometimes proDPI if I get prints from them.

I do use .tiffs for prints and will likely use them for processing in the future for this particular purpose.

Pat

Patrick Gauthier
16-Jun-2016, 08:02
Hi Lachlan,


Why not just use .tiff with properly scanned (unclipped) settings? Given it's lossless/uncompressed, you won't be losing data.

Yeah I'm going to start doing this from now on when my needs are for dark yet contrasty images.

Pat

Patrick Gauthier
16-Jun-2016, 08:07
Hi Peter,


Ok. So you get the image how you like it in Lightroom, but when it's exported to Photoshop it's changed? Is that right?

Yes that's correct. Whenever I export it as any file type other than .DNG (Adobe's RAW type format), I loose contrast in the darks and shadows. Even exporting as photoshops and lightrooms .psd format. Only saving as .DNG preserves the image (because it's not actually converting the RAW file).


Pro Photo RGB is a huge color space. About 13% of it's colors are imaginary colors that aren't visible. It's a great space if your image has some really saturated colors, but a bw photo doesn't have any. Pro Photo RGB's gamma is also 1.8, unlike sRGB's and Adobe 1998's 2.2. Either of those would be a better choice for your output space.

Speaking of color spaces, what's your working/editing color space in Photoshop? If there are some conversions between spaces happening they could cause a visual difference in the image.

I believe the lightroom and photoshop colour space is either pro photo RGB or aRGB. I wonder, I've tried a few different colour spaces but none seem to be better than the other. I know Camera Raw has a grey gamma 2.2 color space for great B&W tones, I will see if there is a way to export a .tiff or .jpeg file with this colour space. Although I am not sure if other software's will support it. We shall see.

Patrick

maxotics
16-Jun-2016, 09:57
Hi Peter,



Yes that's correct. Whenever I export it as any file type other than .DNG (Adobe's RAW type format), I loose contrast in the darks and shadows. Even exporting as photoshops and lightrooms .psd format. Only saving as .DNG preserves the image (because it's not actually converting the RAW file).

I believe the lightroom and photoshop colour space is either pro photo RGB or aRGB. I wonder, I've tried a few different colour spaces but none seem to be better than the other. I know Camera Raw has a grey gamma 2.2 color space for great B&W tones, I will see if there is a way to export a .tiff or .jpeg file with this colour space. Although I am not sure if other software's will support it. We shall see.

Patrick

"Whenever I export it as any file type other than .DNG (Adobe's RAW type format), I loose contrast in the darks and shadows." The converter only does what you ask it. Sorry if this sounds rude but it doesn't sound like you understand what happens when you convert from essentially a 48-bit image to 24-bit. We can only see around 16 million colors. RAW can hold up to 4 trillion shades of color! When you convert, you have to THROW out data. If you want to keep contrast in the shadows, you have to throw out detail in the highlights, and visa-versa. You can't expect the converter to predict what visual data is important to you. It sounds like you don't like the default of one program over the other.

"I believe the lightroom and photoshop colour space is either pro photo RGB or aRGB" Color-space is meaningless by itself. It is printer/monitor dependent. You chose depending on your equipment, NOT depending on the accuracy you want in color. Most color-spaces allow colors beyond any difference we can tell. Especially if we're men, women see color better than we do. Double especially if we're old men ;)

Patrick Gauthier
16-Jun-2016, 10:16
The converter only does what you ask it. Sorry if this sounds rude but it doesn't sound like you understand what happens when you convert from essentially a 48-bit image to 24-bit

This is exactly the point, I am telling it what to do. . . through lightroom and/or photoshop processing, or even more directly with camera raw. If the issue is that the conversion looses information, I can accept that, and move on. And yes, I don't understand the exact process of converting RAW to an image. As a consumer, I was under the assumption that adobe would take care of that for me. If you have any references or resources to share, please do.

Peter De Smidt
16-Jun-2016, 13:24
In Lightroom you can export as sRGB, Adobe RGB (1998), or ProPhotoRGB. For this use, choose sRGB . In Photoshop, go to the Edit menu. Choose color settings. Your screen should look like the attached file, with the exception that your working space should be sRGB.

If you also work with color images, you can use Adobe RGB (1998) as your Lightroom output file, and also as your Photoshop working space. Before saving a jpg for web use, though, you would need to convert the file to sRGB.

The bigger color spaces are mainly for images with saturated colors. In particular, do not use ProPhotoRGB for images that are mainly neutral.

The Joker
16-Jun-2016, 14:26
what profile is the file in when it leaves lightroom?
what are your colour settings in photoshop doing when opening a file? Do they use profiles, leave as is or convert to a different profile?

You should check these things and report back.

Patrick Gauthier
16-Jun-2016, 17:17
what profile is the file in when it leaves lightroom?

Typically I just choose sRGB. But in this particular case I've also tried aRGB and prophotoRGB with no noticeable difference.


what are your colour settings in photoshop doing when opening a file? Do they use profiles, leave as is or convert to a different profile? Upon import, the color profile of the RAW files (actually sony ARW files), according to their file properties (I assume this is the truth) is aRGB.

I feel this thread has been hi-jacked by talk of color profiles. I should re-emphasize I'm working with B&W negatives, and either de-saturating or selecting the "black and white" treatment of the imported files in lightroom. I'm not doing a colour conversion or anything like that, so will the colour profile make a big difference? So far my various exports with different colour profiles has not made any difference.

I think maxotics description of the raw conversion is probably a likely explanation for what I'm having experiencing.


you convert from essentially a 48-bit image to 24-bit. . . When you convert, you have to THROW out data.

maxotics
16-Jun-2016, 17:50
This is exactly the point, I am telling it what to do. . . through lightroom and/or photoshop processing, or even more directly with camera raw. If the issue is that the conversion looses information, I can accept that, and move on. And yes, I don't understand the exact process of converting RAW to an image. As a consumer, I was under the assumption that adobe would take care of that for me. If you have any references or resources to share, please do.

Cambridge In Color (http://www.cambridgeincolour.com/tutorials/raw-file-format.htm)is very good. Also this, bit depth (http://www.cambridgeincolour.com/tutorials/bit-depth.htm)

First, I find this stuff frustrating myself. So please don't think I feel I know everything ;)

A RAW file is based on the bayer sensor, (http://www.cambridgeincolour.com/tutorials/camera-sensors.htm) where a pixel is either red, green or blue. Each pixel generally takes a 14-bit value (varies, but anyway). Because you're scanning negatives, which probably have less resolution than your cameras, it doesn't really make sense to keep that amount of separate, sensor-position, color detail. That's why others have suggested just saving to a high-bit depth TIFF (getting rid of the demosaicing issue--combining the colors). With a TIFF, you have full color information at each pixel, or 65,536 for each primary color, whereas JPEG has 256 shades of each color.

Okay...let me try a different explanation... When you look from the inside to the outside your pupil dilates so you can see shadow detail from the inside to the outside. You can't make out detail in both inside and outside if your pupil doesn't limit the light. In a sense, the RAW file has the data for both inside and outside. When you convert from RAW/TIFF to 8-bit JPEG you are focusing in on the data you want to see (inside or outside). Perhaps I'm making this worse--a bit in a rush.

Then you have the problem that even when you decide what data you want from your RAW, to show inside shadow detail, or outside, then you must make sure your JPEG matches your monitors calibration so black is the same black as you'll print, and others see.

Peter De Smidt
16-Jun-2016, 17:50
You work with BW negatives, but you aren't scanning as BW, and you aren't making the image a BW file in your raw processor. It's a desaturated image in a color space. I've done quite a bit of scanning with a dslr....but I won't hijack your thread any longer.

The Joker
16-Jun-2016, 17:58
how does a bit get a rush?

maxotics
16-Jun-2016, 19:10
how does a bit get a rush?

When it's going out for a byte ;)

I was thinking some more of the OP's confusion. Perhaps it is that he thinks of RAW files as having the same range from black to white, but with more "detail" vs JPEG, say, in the shadows. That could lead to confusion. What is "black" in any image is relative to the 6 stops of dynamic range we see. So looking outside, black might be 6 EV and the highlights 12EV, whereas, inside black would be 2EV and a indoor light 8EV. A full-frame camera can generally capture 12-stops of dynamic range (though the bottom and top not as good as the middle of course). He may think that both a RAW file and JPEG agree about where black and white is.

All detail/contrast is a function of essentially where you place that 6-stop black-to-white range on your RAW data.

Patrick Gauthier
16-Jun-2016, 19:59
You work with BW negatives, but you aren't scanning as BW, and you aren't making the image a BW file in your raw processor. It's a desaturated image in a color space. I've done quite a bit of scanning with a dslr....but I won't hijack your thread any longer.

Thank you Peter, I really do appreciate your help.

Patrick

The Joker
16-Jun-2016, 20:20
very often people like to put a little warmth into their B&W images which equates to using a warmtone paper or even a neutral paper which is very slightly on warm side. You can't do that with Gray gamma 2.2 profile. And besides all image software uses profiling even if you can't control it. But you can in PS. So profiles are very relevant whether you use gray or colour. There is mapping from your image to the monitor profile which goes on without you knowing about it even if your system is using its default profiles. Most people seem to calibrate their monitors these days. Have you done that? I ask becasue photohop used to automatically install adobe gamma loader by default. Don't know if it still does with current versions but I found it a real pain and switched it off. That allows you to calibrate your monitor and not have PS adjust it. Then you can use whichever profile on your images as you like but as others have suggested, sRGB or Gray Gamma 2.2 or Adobe RGB.
And do not keep converting profiles on an image. You should only do it once as multiple converts are lossy. If you convert from sRGB to Adobe RGB and then convert Adobe RGB to sRGB you don't end up with the same as you started with. So if you need to do a second profile change you should use undo to go back to original profile and then convert to new one.
That means that once Lightroom or your camera has set the profile of an image you shouldn't change it again unless you want to lose data. So that means its best to either let your camera set it or output RAW and only convert to working profile once and keep it that way. If Lightroom has converted to sRGB then make sure PS is using sRGB as its working profile or don't let PS convert to a different profile when you open file in PS.

Again personally, if you have adobe gamma loader running I would stop it and remove it from your windows startup folder. Then calibrate monitor and then play with profiles to your hearts content.

I am assuming you are running windows and not a Mac. If you are running a mac then ignore what I say as I have no idea if exact same applies regarding PS but I suspect its similar.

Patrick Gauthier
16-Jun-2016, 20:27
I feel this thread has been led astray. . . but I think I can provide some clarity for others who may be encountering the same issue, and so that maybe we can move forward, although perhaps my original description/question has not been clear enough to some.


Hi LFF!

I shoot 4x5 B&W and by various means scan my negatives and post-process with lightroom/photoshop. My scans are RAW files and are quite large (~170 mp). About 99% of the time I can convert these while still preserving the digital editing I have done. However, when I have a particular dark and contrasty scene (especially a lot of micro contrast), the conversion cannot handle the dark tones and I'm left with something 'blander' than the RAW file.

Does anyone else work with RAW scans and encounter similar issues? Are my expectations too high?

From a practical point-of-view

1) This issue rarely surfaces as most of my images do not have such a high demand for shadow detail and contrast.

2) It is likely my expectations of RAW to .tiff/.jpeg conversions are too high in this particular situation.

3) Colour profile plays a role in controlling B&W tones, but exporting with many different RGB profiles provided no noticeable benefit for this particular image.

4) A working solution is to do the editing with a .tiff file instead of RAW to avoid the un-expected change upon exporting.

5) There may be other practical solutions out there that I will be exploring and reporting on.

Thank you all for your input!

Patrick Gauthier
16-Jun-2016, 20:30
Again personally, if you have adobe gamma loader running I would stop it and remove it from your windows startup folder. Then calibrate monitor and then play with profiles to your hearts content.

Yeah I've been through monitor calibration, I will take a stab at stopping adobe gamma loader though,

Thanks for the suggestion!

The Joker
16-Jun-2016, 21:14
I don't have lightroom so don't know what it can and can't do. However, my understanding was that it doesn't actually edit the image but instead keeps a history of adjustments which are applied to your working file in memory only. I'm presuming your "export" applies all the changes to the physical file including converting to the profile you specify.
If it looks different in PS then it WILL be a profile or adobe gamma loader problem so I don't think the topic has gone astray at all.
Your edit from RAW to whatever in lightroom should be showing you the same as you see in PS.
If you export the file from Lightroom and then rename the file and load that exported file into lightroom, does it look the same as it did before the export? You only mentioned it being different in PS which is why I suspected colour profiles being the cause. But if its different when reopening the exported file in Lightroom then I could understand it being the RAW to Jpeg conversion. However, I assume your RAW edits in lightroom should be showing you what the output file will look like except jpeg normally only uses 24bit colour which could cause a change but you should be seeing that change on screen before the export since your monitor will only be upto Adobe RGB at best and may only be upto sRGB.
And in your original post you specified jpeg using photoproRGB as being the exported image file. Does PS convert that to a different profile when you open it? I did ask before but you didn't answer this. Just trying to nail down exactly where the loss is actually happening. Maxotics may well be right but you should be seeing that loss in lightroom and not just PS.

Patrick Gauthier
16-Jun-2016, 21:38
If it looks different in PS then it WILL be a profile or adobe gamma loader problem so I don't think the topic has gone astray at all.

I will continue to explore this option. I wish I had more time, this is all happening so fast! :eek:


If you export the file from Lightroom and then rename the file and load that exported file into lightroom, does it look the same as it did before the export? You only mentioned it being different in PS which is why I suspected colour profiles being the cause. But if its different when reopening the exported file in Lightroom then I could understand it being the RAW to Jpeg conversion.

Yeah it is also different when imported back into lightroom, the original screenshot i posted is of the comparison in lightroom. I should have been more clear, my apologies.


And in your original post you specified .jpeg using photoproRGB as being the exported image file. Does PS convert that to a different profile when you open it? I did ask before but you didn't answer this

PS has kept the assigned color profile when imported.


Just trying to nail down exactly where the loss is actually happening.

Much appreciated!

Patrick

The Joker
16-Jun-2016, 21:59
Yeah it is also different when imported back into lightroom, the original screenshot i posted is of the comparison in lightroom. I should have been more clear, my apologies.


In that case the problem is in Lightroom so PS is irrelvant at this stage. It may become relevant but I'll forget about PS for now.


PS has kept the assigned color profile when imported.

When you say assigned do you mean "assigned to" or do you really mean "converted to". There is a big difference. Assigning doesn't change the physical file, it just maps the output using the assigned profile. e.g when sending the file to the monitor or printer. Converting actually modifies the files pixel values using the closest match it has available to the original profiles colour for that pixel. Closest meaning within the new profiles colour space. The vast majority of pixels will have values as before the convert but some of the original profiles colours may not exist inside the new profiles colour space and so there is no direct equivalent and it gets as close as possible. It may be that the profile being converted to has a larger colour space than the original so no "closest colour match" takes place at all and what will actually happen is that the original colour space pixel values (the from profile) won't fill the new profiles(the to profile) colour space.

You specified photoproRGB which is an extremely large colour space. This means your scan will easily fit inside it especially since its of a B&W neg. The convert to that may well result in a flat looking image. To use an analogy, its like putting a 5 stop range neg directly onto 7 stop range paper without increasing print contrast. If you put it in the middle of the 7 stop range then there is a missing stop at either end and the blacks won't be black as possible and the whites won't be as white as possible. You could place at the shadow end of the 7 stop range so blacks are black but whites would be 2 stops short of being white or you could put it at the highlight end so that whites are pure white but blacks are 2 stops short of being pure black.
So I think the photoproRGB profile is not a good choice for black and white images. I would use a profile that your camera is able to output in. That way your export should more closely fill the colour space. I think most cameras have sRGB and Adobe RGB but if camera can't output in photoproRGB then don't use it as its probably too big for your files although you can probably correct by just using levels tools to pull in sliders either end of histogram which will increase contrast to fill the colour space of your images profile.

On the other hand, Maxotics may be correct but I don't understand why you are not seeing the effect on screen before your export unless lightroom is not applying the convert until you actually do the export so you never see it in lightroom until you import the exported image. And all of this doesn't explain why you see no difference when using sRGB or Adobe RGB unless you have been converting the already converted image when infact you should be starting again each time using the original file from the scan for the reasons I gave earlier about convert being lossy.

Patrick Gauthier
17-Jun-2016, 07:36
When you say assigned do you mean "assigned to" or do you really mean "converted to".

The camera color profile is aRGB, when imported to lightroom, it is imported as aRGB. I do all my work with this profile. Throughout this thread I have mentioned exporting with several different color profiles (this is the "converted to" step you are referring to). However, there is no important difference (to me as a photographer in this particular situation - I'm not trying to say it never makes a difference) when exported as either the original color profile, or converted to another. The conversions were made in response to many people here, and elsewhere, explaining that I play with different profiles to see if that will fix the problem mentioned in my original post. It does not.

I have a lead from another forum that the issue may be related to lightrooms develop module in terms of it's interpretation of the image, as the same (unexported/ work-in-progress/ original raw + edits but not exported yet) seen in lightrooms preview module has the same issue as the exports (a duller look). An issue I didn't originally notice because I typically just export from develop, and because since the files are so large the build previews takes forever so I'm not keen to switch back and forth. So the issue may not be related to RAW conversions either, and rather a lightroom issue.

I will report back when I have investigated further

The Joker
17-Jun-2016, 07:57
It is unclear to me what the aRGB profile is. I have never used it but have only ever seen it referred to RGB with an apha channel. Am I correct in this?
If it is an alpha channel and the A channel is not 100% then you will lose that when converting to jpeg since jpeg doesn't handle alpha channels.
Why you would use an alpha channel in a normal photograph I don't know. Its usually used for doing overlays or displaying semi transparent online and not in normal photo processing.
If aRGB is something else other than RGB with an alpha channel then please enlighten me. Do you really mean Adobe RGB, the terminology makes a difference to everyones understanding of it ?

Patrick Gauthier
17-Jun-2016, 11:48
It is unclear to me what the aRGB profile is. I have never used it but have only ever seen it referred to RGB with an apha channel. Am I correct in this?

I believe you are correct. I'm not sure why the sony nex would save the raw file with a transparency and have it less than 100%. That would be very sneaky of them. I'll have to double check when I get home, in my rush to post I may have indeed mixed up aRGB and adobe RGB.

Either way, whenever I export it as any file type other than .DNG (Adobe's RAW type format), I loose contrast in the darks and shadows. Even exporting as photoshops and lightrooms .psd format. So if there were a transparency, would it not be applied to a .tiff or .psd?

Patrick

The Joker
17-Jun-2016, 12:40
not sure about tiff but it should be saved in a psd. But why use an apha channel anyway? If you need one for graphics creation you can add one in photoshop later.
If you can, use Adobe RGB1998 or sRGB as output from camera. Adobe RGB1998 is probably better for colour images and sRGB is adequate for B&W but if you are capturing in colour which I expect you are, then use AdobeRGB1998 and desaturate in PS where you will have better control of it in a fully colour managed application. And when I say colour managed I mean an application where you can control your profiles regardless of B&W or Colour and not that your image is a colour image.
I think Peter had it right in the first place. And Maxotics has it right with reducing pixel depth too. It's a been a while since I messed with colour profiling.
jpeg is 24 but colour without an alpha channel.
If you do have an alpha channel then you can try exporting as tiff or 24bit png which can have alpha channel and is non lossy (unless you are converting from higher bit depth) but will create big file sizes. png is usually used for online display with transparency being adjustable.

Patrick Gauthier
17-Jun-2016, 21:30
It's all adobe RGB, from the moment the ARW file is imported. Not sure where aRGB was spawned in my mind, most probably my laziness in skipping 5 keys whilst typing.

The Joker
18-Jun-2016, 04:49
So keep everything in Adobe RGB then and don't convert or assign to other profiles.

So what you are seeing must be due to the convert from raw to jpeg. Jpeg is a 24bit file. So export to TIFF in high bit depth using adobe RGB 1998. Then open exported file in lightroom and see if there is a change. IF not then you will be sure its the convert to jpeg or rather 24bit that is causing the problem. If there is a visible change then you will be sure its the convert from raw that is causing the problem. But I would have thought decent software would show you the change before you actually export/save the file. Not having lightroom I can't test this.

Let us know for future reference.

Patrick Gauthier
24-Jun-2016, 13:25
Sorry for not posting this sooner.

As suspected, it's not a color profile issue, but it's also not a RAW conversion issue.

It's actually how the the presentation of blacks is influenced by the interaction between how lightrooms develop module re-sizes its previews and handles its "details" adjustments with the "fit" preview ("fit" previews the whole image). For those who don't use lightroom, the develop module is where you do all your editing, and the details panel controls sharpening and noise reduction. The develop module can't be avoided in terms of lightroom workflow - unless you only use presets.

The title of the thread is therefore a little misleading, as the issue is not directly with the RAW conversion.

Please see the two references from the adobe forum by trshaner - a very competent adobeist. ssprengle from the adobe forum was also very helpful.

https://forums.adobe.com/message/8817522#8817522

https://forums.adobe.com/message/7327718#7327718

From now on I will always preview the edited image in the Library module in lightroom, as the Library module "fit" preview more accurately represents the exported image. The most accurate way to deal with the issue is to work with 1:1 previews, as there is no re-sizing being done. However, a 1:1 preview is more technically useful than artistically useful, so that doesn't really help (you need to see the big picture - no pun intended).

It also doesn't matter if you do the editing with a RAW file or TIFF, the representation of the darks in the develop module "fit" preview will still be darker because there is still re-sizing taking place to see the whole picture.

In case you're interested, here is the image that caused this all.

https://www.flickr.com/photos/126831719@N03/27091022753/in/dateposted-public/lightbox/