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02-12-2020, 03:54 AM   #31
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QuoteOriginally posted by biz-engineer Quote
Now I imagine I'd buy this super expensive Fuji GFX100 because I want the ultimate image quality (which would justify that much money spent) while I'd actually cut off some colors out of well saturated color images in to sRGB JPEGs because exporting the GFX100 file as 16bits TIFF (Adobe RGB or ProPHoto) would just be insane *. Such large file would make my processing laborious and it would use up so much of my storage space. Now I think our computers are not ready to deal comfortably with such large files. I guess 50Mpixels is the maximum with state of the hart PC / Mac technology. Digital cameras are ahead of computer and display tech.

That seems to tally with my own thinking. I save my finished photos for viewing as JPEG rather than TIFF because of the file size and because my PC is quite slow at displaying big TIFF files. So my reasoning is that I might as well use sRGB all the way through, so that I'm always seeing the colours that I'll actually see in the final version. Although of course I keep it all in 16bit until I do the final JPEG export.

Because I tend to use layers and masks, I'm used to ending up with Photoshop PSD files over 200MB just for shots taken with the humble 10MP CCD that I get the most pleasure from shooting with. I dread to think what sort of file sizes I'd end up with using something like the Fuji GFX100 (although I have to confess that I'd like to try - some of the sample shots I've seen from that camera have been truly superb).

02-12-2020, 05:12 AM   #32
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QuoteOriginally posted by Dartmoor Dave Quote
but here's my question: Will I see any colour shift when I finally convert from AdobeRGB in Photoshop to sRGB jpeg for general viewing on screen?
I think it will depend on how much of the AdobeRGB "edge" colours (not in the sRGB gamut) are contained in your image. For most of my processing I notice no difference at all. That does not mean there is no benefit from working in AdobeRGB and16 bit. Any extensive editing should always show smoother transitions and less artefacts when working in the widest gamut and bigger bit size, when you finally create a 8 bit sRGB jpeg from your work.

When you do some testing, do check out the histogram though, before and after you "convert to profile". That will change even if your eyes tell you otherwise
02-12-2020, 06:51 AM   #33
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QuoteOriginally posted by pschlute Quote
I think it will depend on how much of the AdobeRGB "edge" colours (not in the sRGB gamut) are contained in your image. For most of my processing I notice no difference at all. That does not mean there is no benefit from working in AdobeRGB and16 bit. Any extensive editing should always show smoother transitions and less artefacts when working in the widest gamut and bigger bit size, when you finally create a 8 bit sRGB jpeg from your work.

When you do some testing, do check out the histogram though, before and after you "convert to profile". That will change even if your eyes tell you otherwise

Thanks. I've played around with some raw files over lunch, just switching between sRGB, AdobeRGB and ProPhoto RGB in camera raw. I see what you mean about there being surprisingly big differences in the histograms, and more significantly for me personally there was a discernible visible difference. Only a slight difference, mostly affecting reds and the appearance of colour contrast, but it's definitely there. Which suggests that if I do switch to editing in a different colour space then I probably will notice a shift when I finally export as sRGB JPEG.

And that's a shame, because it was obvious at first glance that ProPhoto RGB gives a much nicer rendering than either of the others. I'm going to have to do some more experimenting to find out just how much of that obviously nicer ProPhoto rendering disappears when I finally export as sRGB JPEG.
02-12-2020, 07:04 AM - 1 Like   #34
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QuoteOriginally posted by Dartmoor Dave Quote
Thanks. I've played around with some raw files over lunch, just switching between sRGB, AdobeRGB and ProPhoto RGB in camera raw. I see what you mean about there being surprisingly big differences in the histograms, and more significantly for me personally there was a discernible visible difference. Only a slight difference, mostly affecting reds and the appearance of colour contrast, but it's definitely there. Which suggests that if I do switch to editing in a different colour space then I probably will notice a shift when I finally export as sRGB JPEG.

And that's a shame, because it was obvious at first glance that ProPhoto RGB gives a much nicer rendering than either of the others. I'm going to have to do some more experimenting to find out just how much of that obviously nicer ProPhoto rendering disappears when I finally export as sRGB JPEG.
It's an interesting dilema, as I see it... work in sRGB, which - for want of a kinder term - is pretty much the "lowest common denominator", and you'll see almost exactly (or very close to) what should be reproduced when exporting with sRGB output profile and viewing on any profiled sRGB-capable medium; or, work in the widest available colour space and gain the potential to export for devices with wider, "richer" colour capabilities - but experience a shift in colour when exporting to "narrower" colour spaces...


Last edited by BigMackCam; 02-12-2020 at 12:16 PM.
02-12-2020, 07:27 AM - 1 Like   #35
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QuoteOriginally posted by BigMackCam Quote
It's an interesting dilema, as I see it...

It's a Pandora's Box I'm wishing I'd never opened with those lunchtime experiments.

AdobeRGB. . . meh. In some ways I preferred sRGB anyway.

ProPhoto RGB. Holy moly! Where has THAT been all my digital photographic life? Now I've seen how much better it made those raw files look, I'm not sure I'm going to be able to leave this one alone.


(Edit: I know I originally called the differences "slight" above, but the more photos I've looked at, the bigger the difference has seemed. And so far lunch has stretched to two-and-a-half hours, but since it's only volunteer work done at home today that doesn't matter.)

Last edited by Dartmoor Dave; 02-12-2020 at 07:37 AM.
02-12-2020, 10:59 AM - 1 Like   #36
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That’s good. You’ve taken your first step into a larger world, Dave. Enjoy!
02-12-2020, 11:55 AM - 2 Likes   #37
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QuoteOriginally posted by StiffLegged Quote
That’s good. You’ve taken your first step into a larger world, Dave. Enjoy!

Those are true words. The last few days have been some of the most informative and educational since I started moving from film to digital back in 2012. I've discovered that DisplayCAL gives me a much more accurate monitor profile than I was getting from Spyder's own software, and I've discovered that from now on I absolutely have to edit in ProPhoto RGB.

It really has been a revelatory few days, and it's sure to have a major influence on the look of my photos from now on.

02-12-2020, 01:08 PM   #38
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QuoteOriginally posted by Dartmoor Dave Quote
and I've discovered that from now on I absolutely have to edit in ProPhoto RGB.
The problem of ProPhoto RGB is that there is no display , nor printer than can show as much as ProPhotoRGB color gamut, the limit will be the maximum the display can do, Adobe RGB seems to be the max for the best monitors.
02-12-2020, 01:34 PM   #39
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QuoteOriginally posted by biz-engineer Quote
The problem of ProPhoto RGB is that there is no display , nor printer than can show as much as ProPhotoRGB color gamut, the limit will be the maximum the display can do, Adobe RGB seems to be the max for the best monitors.

That's true, but after going back through a couple of dozen raw files from the past few years this afternoon I think there's a very clear difference in the way the data is rendered within the colour range that my monitor is able to display. I'm left with no doubt that ProPhoto RGB renders my raw files better than I've ever seen them before, even though I accept that I'm not seeing the full gamut that it's capable of. There's also no doubt that a big chunk of that rendering is lost after converting to sRGB to save as a final JPEG, but I think enough of it remains that I'll be using ProPhoto from now on.

I accept that this all very subjective rather than objective, but I'm just calling it as I see it. To my eyes, it's not about how far the colour space goes beyond what you can actually see on the monitor; its about how it renders within the range that you actually can see. And I should probably point out that this was most definitely not the conclusion that I was hoping and expecting to end up with. I'd assumed that I'd end up with confirmation that I might as well just edit in sRGB anyway, but I didn't.

(And apologies to Oxfam for not doing any of the classical vinyl online listings that I was planning to do this afternoon. That's volunteers for you. . . )

Last edited by Dartmoor Dave; 02-12-2020 at 01:40 PM.
02-12-2020, 01:52 PM - 1 Like   #40
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QuoteOriginally posted by biz-engineer Quote
The problem of ProPhoto RGB is that there is no display , nor printer than can show as much as ProPhotoRGB color gamut, the limit will be the maximum the display can do, Adobe RGB seems to be the max for the best monitors.
Whilst it would be nice, it doesn't matter so much that you can't see the entire ProPhoto RGB gamut on your display or printer. Using ProPhoto RGB as your working colour space when editing on, say, a 100% sRGB monitor won't allow you to see saturation outside the sRGB gamut (due to the limitations of the monitor), but you will see the ProPhoto RGB representation for tones that fall within the monitor's profiled gamut, and that will be less compressed than with the sRGB working space... images should look somewhat "richer", depending on content. Furthermore, and most importantly, by working in ProPhoto RGB you'll retain and apply edits to a much wider representation of the "real world" colour captured by the camera's sensor, instead of shoe-horning it into a narrower colour space such as sRGB or AdobeRGB at the point of editing. Finally, soft-proofing can be used to see how the image will look with sRGB and other output profiles (depending on the capabilities of your display). As I see it, you lose nothing by working in ProPhoto RGB, and gain a lot.

I guess, ideally, every one of us ought to edit in a ProPhoto RGB working space - and soft-proof - on a monitor with the widest available gamut, and output only to profiled devices with gamuts no bigger than our monitor can fully represent. Only that way can we be sure that we're seeing every tone represented in our working colour space and output-profiled files. In practice, though, most of us have monitors that don't even display the entire sRGB gamut, while some have 100% sRGB, and a small percentage have 100% AdobeRGB. But all of us will be able to see the tonal expansion (or, rather, lack of tonal compression) when working in ProPhoto RGB, even if we only see the range that fits within our monitor's profiled gamut.

Dave - I believe what you're seeing when working in ProPhoto RGB is the lack of tonal compression you'd have experienced in the sRGB colour space...

Last edited by BigMackCam; 02-12-2020 at 03:38 PM.
02-12-2020, 03:24 PM   #41
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I've just been looking around the web, and this is a pretty good article extolling the virtues of ProPhoto RGB colour space for editing. Many of the very points we've discussed are covered in the article and comments, and there's a nice little video to accompany it...

Why Use the ProPhoto RGB Color Space? (Podcast 423) · Martin Bailey Photography
02-13-2020, 01:00 AM   #42
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QuoteOriginally posted by BigMackCam Quote
but you will see the ProPhoto RGB representation for tones that fall within the monitor's profiled gamut, and that will be less compressed than with the sRGB working space...
The CMM engine does the real time color space fit to display. If the display color space is exactly sRGB, there should be no difference between displaying an sRGB converted image and a ProPhotoRGB version of the same image.
But...

---------- Post added 13-02-20 at 09:07 ----------

QuoteOriginally posted by BigMackCam Quote
Dave - I believe what you're seeing when working in ProPhoto RGB is the lack of tonal compression you'd have experienced in the sRGB colour space...
... the display gamut can be larger than sRGB and smaller than Adobe RGB , or it's also possible that a wide gamut display is slightly larger than Adobe RGB, yet smaller than ProPhoto, that's where I believe the superior rendering comes from real time displaying of an ProPhotoRGB image on a monitor.

My monitor is mainly sRGB, slightly wider than sRGB but it's not a dedicated "photographer's" 99% Adobe RGB monitor. Like Dave, if I display an Adobe RGB (or ProPhoto RGB) on my "sRGB" type monitor, the image is better rendered than the same image exported as sRGB displayed on the same monitor. It's just that the CMM (Color Management Module) uses as much as the monitor can do when the image color space is larger than the monitor color space. If the image is already sRGB the colors at the outter edge of sRGB have been removed by the sRGB export, the CMM only display what's in sRGB even if the monitor is capable of more. However, I see no difference of image rendering on my monitor between Adobe RGB and ProPhotoRGB, because my monitor gamut is fully inside Adobe I believe.

One thing that puzzles me is the difference between my 8 years old 27" "special offer" Philips IPS display fr which I paid 200 euros, and my DELL notebook display of 2019 for which I paid 1400 euros. The 200 Euros display exceeds sRGB (110% or so), while the DELL IPS supposed to be the superior version covers only 60% of sRGB ! No matter how many calibrations I've tried, I've never been able to get that notebook display gamut more than about 60%. At least it was good to become aware about the 60% limitation, I now know that I should never edit color images on the notebook display. And I guess 200 euros of 8 years ago was a pretty good deal .

Last edited by biz-engineer; 02-13-2020 at 01:24 AM.
02-13-2020, 02:26 AM   #43
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QuoteOriginally posted by biz-engineer Quote
The CMM engine does the real time color space fit to display. If the display color space is exactly sRGB, there should be no difference between displaying an sRGB converted image and a ProPhotoRGB version of the same image.
But...

---------- Post added 13-02-20 at 09:07 ----------


... the display gamut can be larger than sRGB and smaller than Adobe RGB , or it's also possible that a wide gamut display is slightly larger than Adobe RGB, yet smaller than ProPhoto, that's where I believe the superior rendering comes from real time displaying of an ProPhotoRGB image on a monitor.

My monitor is mainly sRGB, slightly wider than sRGB but it's not a dedicated "photographer's" 99% Adobe RGB monitor. Like Dave, if I display an Adobe RGB (or ProPhoto RGB) on my "sRGB" type monitor, the image is better rendered than the same image exported as sRGB displayed on the same monitor. It's just that the CMM (Color Management Module) uses as much as the monitor can do when the image color space is larger than the monitor color space. If the image is already sRGB the colors at the outter edge of sRGB have been removed by the sRGB export, the CMM only display what's in sRGB even if the monitor is capable of more. However, I see no difference of image rendering on my monitor between Adobe RGB and ProPhotoRGB, because my monitor gamut is fully inside Adobe I believe.
I believe the "elephant in the room" here is the "colormetric rendering intent" in each of the multiple conversions taking place - raw file to editing suite's working colour space, editing suite to the selected display profile, editing suite to the selected printer profile, editing suite to the export file's selected profile, export file to image viewer's selected display profile, export file to selected printer profile etc. In each conversion, a "colormetric rendering intent" - perceptual, relative colormetric, etc. - will have a different impact on the mapping of colours from source to destination colour space... and, depending on the intent, both out-of-gamut and in-gamut colours may be mapped differently...

It's quite the rabbit hole, isn't it?

QuoteOriginally posted by biz-engineer Quote
One thing that puzzles me is the difference between my 8 years old 27" "special offer" Philips IPS display fr which I paid 200 euros, and my DELL notebook display of 2019 for which I paid 1400 euros. The 200 Euros display exceeds sRGB (110% or so), while the DELL IPS supposed to be the superior version covers only 60% of sRGB ! No matter how many calibrations I've tried, I've never been able to get that notebook display gamut more than about 60%. At least it was good to become aware about the 60% limitation, I now know that I should never edit color images on the notebook display. And I guess 200 euros of 8 years ago was a pretty good deal .
Traditionally, it seems that laptop / notebook displays have been less capable than desktop displays. I'm not sure why that is. My five or six year old budget HP desktop monitor - now pressed into service as my Dad's "new" desktop display - comfortably displays almost full sRGB and is surprisingly accurate even without a custom profile. When, though, at the back end of 2018 I was buying a new laptop, the choice of machines with 100% sRGB gamut (or greater) was very limited indeed. I ended up paying a big premium for a machine with a 15" 4K 100% AdobeRGB screen (I didn't actually want 4K, but none of the Full HD options offered 100% sRGB or greater)...

Last edited by BigMackCam; 02-13-2020 at 04:01 AM.
02-13-2020, 02:39 AM   #44
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QuoteOriginally posted by biz-engineer Quote
The CMM engine does the real time color space fit to display. If the display color space is exactly sRGB, there should be no difference between displaying an sRGB converted image and a ProPhotoRGB version of the same image.But...

That's really why I was so mindblown yesterday. I wasn't expecting to see any visible difference, I hated the fact that I was seeing one, I tried to convince myself that I wasn't, and I ended up having to accept that I was.

Given that a colour space is basically a triangle within which points for specific colours can be mapped, and that a wider colour space is effectively just a bigger triangle, what's actually happening when I view a ProPhoto file on a monitor like mine that can only display 98% of sRGB? Is it remapping points in the bigger triangle (ProPhoto) as points in the smaller triangle (sRGB) to scale the bigger triangle down? Or is it only displaying the points that fit inside the smaller sRGB triangle and just ignoring all the points in the ProPhoto triangle that fall outside that?

Sorry if that's a hopelessly simplistic way of putting it.
02-13-2020, 02:51 AM   #45
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QuoteOriginally posted by BigMackCam Quote
It's quite the rabbit hole, isn't it?

It really is, and I'm starting to suspect that it's one of those things that can only really be understood if you're familiar with a branch of mathematics that's beyond me.
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