Does soft-proofing work without looking to the output profile?


#1

I make a new topic out of this:

One question: Are you sure that the soft-proofing works as it should?

When I open a wide gamut test chart, output profile sRGB and switch
on soft-proofing and gamut-indicator, I get a lot of grey fields showing
the colours that the proof profile cannot indicate.

But when I switch to another output profile, e. g. ECI-RGB v2, the
grey fields should change in some way in comparison to sRGB, but
anything stays the same.

RT seems to indicate the gamut control independent of the image
output profile, but the output profile is essential for the colours in
the image and if they can be displayed by the printer.

Soft-proofing colour profile was ISOcoated_v2_300_eci in both cases.
It seems not to make a difference, if the source was a JPG or a raw file.


#2

Hi,

could please somebody give me an opinion to that?

Did I do something wrong or understand it wrong or is the softproofing not ready to work with already?

Thank you,
T70


(Elle Stone) #3

Hi @T70 - Do you have a link to your wide gamut test chart? I downloaded your ECI profiles from http://www.eci.org/en/downloads . But without a link to the test chart, it’s not possible to try to answer your question, just because it’s entirely possible that the color gamut of the test chart lies entirely within the intersection of the sRGB and ECI-RGB v2 profiles.


(Andrew) #4

hi @T70, I’m no expert in this but I’m interested to check my understanding in any case, so this is my explanation FWIW.
Firstly, forget about output profile. You are editing in RT, it has a load of numbers in memory and a defined WORKING profile, so RT knows all about your colours. You now choose a profile to do soft proofing in Preferences, and so RT can identify all the pixels which fall outside the gamut represented by the print proofing profile. This is all valid and has nothing to do with an output profile, which is why the grey doesn’t change when you change the output. You might make some more adjustments then you want to save the image. Now you can choose any output profile you want provided it is big enough to hold your image adequately. If you need the print profile applying to the output, perhaps because the print shop requires it that way, then you use the print profile as the output profile - and you can do this provided it’s RGB, following a recent change made by the wonderful developers. I think that’s it!


(Andrew) #5

@Elle has replied whilst I was typing…!


(Elle Stone) #6

And @RawConvert replied just as I was about to start typing :slight_smile:

Anyway, what @RawConvert said seems right based on what I know about RawTherapee soft proofing, which is not much.

The question I actually wanted to answer is whether soft proofing from sRGB or ECI-RGB to ISOcoated_v2_300_eci would give different results, assuming the output profile was used as the source profile for soft proofing. To answer this question requires having the test chart.

But in RT apparently the output profile isn’t used as the source profile for soft proofing, which seems a bit odd but perhaps useful in the context of overall RT functioning.

Then I was going to ask the following questions about RT soft proofing, which I’ll go ahead and ask:

What source profile does RawTherapee actually use for soft proofing to a user-chosen soft proofing profile?

It might be using CIELAB?
Or the user’s chosen RGB working space?
Or it might be using the user’s chosen output profile? (apparently not)
Or the image input profile?

And does RT use clipped or unclipped conversions from the image’s original input profile (or the camera raw profile for raw files) to CIELAB, and/or to the user’s chosen RGB working space, and/or to the output color space, and/or to the soft proofing space if the soft proofing space actually supports unclipped conversions?

There seem to me to be many “moving parts and possible paths” in RT soft proofing. I would love to see an explanation of the actual conversion paths for RT soft proofing, taking into account the issue of “clipped vs unclipped” ICC profile conversions.


#7

Hello Elle and RawConvert,

thank you for inspiriting this thread :wink:

You can test it with this image from Wikipedia:
Many colours

This seems to be the opinion of Rawtherapee makers, too. But this is not the idea of softproofing. Softproofing shall answer the question: which of the colours of my image will be representable on a defined print?

And I am sure that only the output image can be meant, otherwise I could not control the advantages of a wider output profile like AdobeRGB or ECIRGB. I do softproofing to decide which output profile will be the best for my image under a defined printing condition.


(Andrew) #8

hi @T70, I’m not sure I can add much more, and I haven’t yet used RT soft-proofing for real / “in anger”.

Can you say exactly where RT fails to meet your needs regarding the question above?

I thought the fundamental purpose of soft-proofing was to check and adjust your image so that you get the result you want when it is printed with a specific printer/paper/ink combination?


#9

@RawConvert You are right. But the printed result is strongly dependent on the output image, since the printer does not have anything else.

Images profiled with AdobeRGB or ECI-RGB have more colours than sRGB images, so there should be a difference in softproofing.

Especially ECI-RGB was designed to fit as many CMYK (=printer) colours as possible.


#10

The issue of soft-proofing in RT-5 is still, in my mind, a very foggy topic. I intend to start a new thread with a more comprehensive approach to the subject. However in the meantime could we finally come to a definitive conclusion about the role of the “Output Profile” in the soft-proofing workflow.

The latest RawPedia has this to say:

Monitor Profile and Soft-Proofing
One can also enable soft-proofing of the preview. This will show you what your image will look like once it gets transformed by the printer profile set in Preferences > Color Management. If you want to adjust an image for printing and you have an ICC profile for your printer-paper combination you could set that as your output profile, enable “Black point compensation” in Preferences so that the blackest black in your image will match the blackest black your printer-paper combination is capable of reproducing, then enable soft-proofing. You will see what your image will look like if you print it.

I am using what I believe is the latest version of RT (from the download site) version 5.0-r1-gk3. I have an ICC profile for my printer (in RGB color space). While I am able to select that profile in Preferences>Color Management, I am not able to select that profile as my Output Profile.
@RawConvert suggests above that a recent change has made this possible. Where is this changed version to be found?

Soft-proofing, as I understand it, is an editing process that allows one to produce a print matching (as closely as possible) the image seen on your monitor. The prerequisites are: having a valid monitor profile and an appropriate printer profile. It also demands the ability to send the edited (proofed) image to the printer. How the hell can that happen if I cannot specify the Output Profile as the space in which the image has been edited?


#11

@mikesan I don’t know what is your system.
If it is windows you should find recent development builds here https://discuss.pixls.us/t/download-rawtherapee-development-builds/2924 .

Choose the dev branch build “RawTherapee_dev_5.0-r1-gtk3-124-gb84e570f_WinVista_64.zip” or more recent.
As it is a deveolpment build, option files are located in …/rawtherapee5-dev


#12

Thanks @gaaned92
Have downloaded the latest (dated today) and will give it a try.


#13

Before I try out the development version let me point out a significant error with version 5.0-r1-gk3.
When one hovers over the soft-proofing icon (edit window) the tool tip shows:

If active lets you simulate de rendering generated by the output profile of the ICM tool.

Demonstrably false. When one changes the output profile to any of the available choices there is no visible change in the image.

EDIT: Although I am unable to discern any change in color appearance when changing output profile, a lockable color picker placed over color patches in image does show very significant changes with output profile, as does the histogram. These changes occur independent of state of soft proof.


#14

I think this is definitely wrong. The profile for soft-proofing has to be adjusted on the Colour Management Tab at Printer (Soft-Proofing).

Mixing up soft-proofing profile and output profile makes no sense. At the latest when you try to adjust a CMYK soft-proofing profile as output profile, you will get a crash in RT, since RT cannot produce CMYK images.

Yes but no :smiley: What you get out of RT will always be an RGB image, mostly sRGB or AdobeRGB. The printer takes this image and converts it to printing colours. The printer does that - not RT. This is why the soft-proofing profile may not be adjusted as output profile.

This is what irritates me, too, and what was the reason for this thread.


#15

@T70

But did you read my edit in that same post:

I should add that, when making this test, my monitor profile was correctly entered in Preferences>Color Management.
Have you tried this and, if so, what results?


#16

I’m sorry - now i did.

No, absolutely not. No changes in color picker values, when changing output profile, and not when switching soft-proofing on or off. Only image getting brighter, when switching on - but the same “getting brighter” independent of the output profile.


#17

@T70

That is indeed strange. The image I am using is one of an X-Rite Color Checker Passport. When I place several color pickers on various patches the values change significantly with changes in output profile. The values are not affected by switching soft-proofing on/off.

As I noted before, my eyes cannot detect any change in the color of the patches when switching output profile. I am using a well profiled and calibrated wide gamut monitor but I can’t say much about my rather ancient eyeballs

I also note that when I turn on the “out of gamut” indicator, several patches show the grey areas (indicating out of gamut). However there is no change in this indicator when switching output profile or, for that matter, no change when switching the printer profile in Preferences>Color Management. The latter is particularly strange since out of gamut indicator should be very dependent on printer profile.

It is possible that altering the printer profile in Preferences does not take effect until the program is closed and restarted. Does anyone know?


(Andrew) #18

hi there. Are you expecting the preview image to change when changing output profile? If so, why?

On my RT (5.0 R1, Ubuntu), the preview changes when I change printer profile; and with no need to re-start RT.


#19

@RawConvert

Hi Andrew.
There is still some confusion about how to display a soft-proof image in preview. It is generally agreed that the printer profile must be entered at Preferences>Color Management. There is still some question about what profile should be selected in Color Management tool>Output Profile. RawPedia suggests that the latter should (also) be the printer profile; although with my version of RT (win7 RT-5.0-r1gtk3) it is not possible.

Note, that while the preview image does not change with output profile, when I place several color pickers on various patches, the values change significantly with changes in output profile. Thus it seems clear that the choice of output profile does affect the preview image, in spite of the fact that my eyes do not detect a change.


#20

Hi @mikesan

I have been following this thread, but have been reluctant to join in, because my information on this is only from following the discussions in github etc, not through actual use. My understanding is…

The output profile does not affect soft proofing, it defines the profile that is used for the final tiff/jpg.
Depending on how you are printing, dictates whether you should use the print profile for the output profile.
If you are printing and your print program is responsible for converting to the print profile, then assign an output profile that is larger than the print profile.
If you are printing, but your print program does not let you select your special custom print profile, then set it as your output profile, and make sure your print program is configured to print without assigning a profile.
If you are sending off to a print service online, set the output profile to whatever they say. If they don’t say, then they probably want sRGB.

Just because the numbers are different, doesn’t mean that the colours are different. The same colour is represented by different RGB values for different profiles. From what you describe, it sounds like the colour picker is showing the numbers for the final output file, rather than the soft proofing profile, the working profile, or the monitor profile.

Perhaps @Hombre can clarify?