RT output profiles and soft-proofing

Software RawTherapee
21

Hi Hombre.

While we have been carrying on a conversation in another thread, I had forgotten this request.

The procedure in P’shop is simple: Convert the jpg file from working space to the printer profile color space. The image itself and the printer profile are here:

image
profile

Again, many thanks for your time and your help.

PS: If you check the profile you will see it is in RGB color space. I can select it easily in Preferences>Color Management, but there is no way (right now) to select it as the Output Profile.

22

@mikesan Can’t you build RT yourself ? Are you on Linux ? I could send you a Windows binary if you want.

23

Thanks Hombre. I am on Win7/64. I am not feeling confident enough to try a build; will wait for the modification to reach the current download. Meanwhile I can still use the printer profile for soft-proofing purposes only even though I will not be able to save the file using that profile for output.

24

hi @Hombre, I’d be interested in this if it’s not a lot of extra work for you, it would get me started printing. I would do most of the processing on my Ubuntu PC, then output to 16bit TIFF, then over to my old Win7 64bit PC, open in your RT, apply the printer profile (which Elle kindly confirmed was an RGB one), save as an 8bit TIFF (or 16 if the print company will take that) and send the file off.

25

@RawConvert if you do your processing on an Ubuntu machine, why not compile yourself? It’s a magnitude easier to do than on Windows.
http://rawpedia.rawtherapee.com/Linux
You could also use ImageMagick to convert/assign the color profile.

26

hi Morgan, I had no idea it might be so easy… do I really need to do just the two 16.10 commands?, i.e.
sudo apt-get update
then
sudo apt-get install etc. etc.

Would I need to first remove my current RT which is done via “ppa:dhor/myway” ?

I tried ImageMagick but on my PC it’s a badly-behaved app prone to crashing, and I’ve removed it. (it also seemed to be installed twice with the same name). Do you know of any other apps, please, which could convert to a printer profile (in case I can’t get the Dev build installed) ?
@Elle, you know loads of apps! Do you know any to do the conversion please? (You mentioned Gimp but I found the associated issues made it too daunting for me)

27

I’d investigate your installation of ImageMagick, it is a stable application used everywhere there are images on the internet. It is not crash prone nor unstable.

2 Likes
28

Well, at the command line:

There’s tificc from LCMS. This can handle 8- and 16-bit integer and also 32-bit floating point tiffs, and also V2 and V4 profiles. To see the available options, just type “tificc”. It’s easier to use if you put the source and destination profiles in the same folder as the image file (makes typing the paths to the profiles easier).

The basic usage is:

tificc list-of-conversion-options-to-use -i input-profile.icc -o output-profile.icc input-image.tif output-image.tif

So if:

  1. you want to use relative colorimetric intent (-t1)
  2. you want to use black point compensation (-b)
  3. you want 16-bit integer output (-w16)
  4. you want to embed the printer profile in the converted image (-e)
  5. the input image profile is “ClayRGB-elle-V2-g22.icc” (-i)
  6. the output image profile is “DC-Colour-labs-Frontier-Glossy.icc” (-o)
  7. the input image is “two-apples.tif”
  8. the output image is “two-apples-frontier-glossy-using-tificc.tif”

Then here is the tificc command:

tificc -t1 -b -w16 -e -i ClayRGB-elle-V4-g22.icc -o DC-Colour-labs-Frontier-Glossy.icc two-apples.tif two-apples-frontier-glossy-using-tificc.tif

LCMS also provides a jpeg version of tificc, but I forget what it’s called.

Also there are “-c” switches that govern the quality of the output. These switches used to be important, but right now I’d have to do some experimenting to confirm. On the LCMS mailing list Marti made a comment that indicated that the switches shouldn’t be used, but the context was matrix profile conversions and the comment possibly doesn’t apply in the latest version of tificc (I’m using LCMS 2.8).

So if you want to experiment, for maximum quality add “-c0” somewhere in the list of conversion options (the exact order doesn’t matter for any of the options, except the input and output tiffs must be at the end). The other options are “-c1”, “-c2”, and “-c3”. I don’t remember what the default is, but it’s not “-c0”.

Here is a sample ImageMagick command:

convert two-apples.tif -profile ClayRGB-elle-V4-g22.icc -profile DC-Colour-labs-Frontier-Glossy.icc two-apples-frontier-glossy-using-im.tif

Does anyone know of any additional options for using IM to convert from one ICC profile to another?

There was a time when IM was hard-coded to use one of the “less precise” -C# options provided by LCMS (confirmed by checking the source code), but I don’t know if that is still the case. Presumably there are switches to use or not use black point compensation and to specify the conversion intent, but I don’t use IM for converting images from one ICC profile to another (I do sometimes use IM, but not for this).

Here is a sample ArgyllCMS cctiff command (cctiff):

cctiff -v -ir -p -k ClayRGB-elle-V2-g22.icc -ir DC-Colour-labs-Frontier-Glossy.icc -e DC-Colour-labs-Frontier-Glossy.icc two-apples.tif two-apples-frontier-glossy-cctiff.tif

Here is what the cctiff options mean:

-v Be verbose (spit out a lot of information about the profiles and such)
-ir (must be repeated for each profile) Use relative colorimetric intent. See the documentation for specifying a different intent
-p Use slow accurate conversion routines
-k Calculate the difference in accuracy between using the slow accurate routines vs using the default routines
“-e DC-Colour-labs-Frontier-Glossy.icc” Do embed the final profile (or other profile of your choice) in the output image (by default no profile is embedded in the output image)

A couple of years ago I did some rather extensive comparisons of the accuracy of ICC profile conversions using round-trip convesions of 16-bit integer images - that in theory should be completely lossless conversions because both profiles had color gamuts that completely encompassed all the image colors - and cctiff provided the most accuracy.

cctiff requires V2 profiles and can work with jpegs and tiffs, including 16-bit integer tiffs, but afaik it doesn’t work with floating point tiffs.

cctiff can be used to chain together a sequence of conversions.

2 Likes
29

hi @Morgan_Hardwood, so I didn’t read the page properly! :flushed:
I’ve now compiled a Dev build and it all seemed to work ok, leading to RT launching, except for one glitch. On doing “~/rt/rawtherapee” I got this error message six times in quick succession in the Terminal window -

(rawtherapee:15448): Gtk-CRITICAL **: gtk_box_gadget_distribute: assertion ‘size >= 0’ failed in GtkScrollbar

Do I need to worry about this please?

30

hi, I re-installed it via the “Ubuntu Software” app but it was no better. However I should say I didn’t know it was mainly a command-line app, whereas I was using it gui-style, e.g. right click file, open with IM. Perhaps I’ll have another go sometime. Thanks.

31

Many thanks @Elle, that’s a fantastic amount of info!
I downloaded LCMS and had a quick look, however it looked a bit tricky! e.g. C code needing compiling, so I’m going to pass on that for now. I will try the latest RT which I built (well my PC built) earlier. But thanks again, you’re a star.

32

It is indeed a CLI application.

You can ignore the gtk errors, gtk spews them everywhere.

33

Hmm, I’m confused. If you have RT installed, or just about any other free/libre image editing application, then you should already have LCMS installed, unless maybe you are using an RT AppImage (or something similar) that tosses LCMS into the build.

But just about every desktop Linux OS in the world should already have LCMS installed.

Did you try typing “tificc” at the command line?

34

Nope, it’s normal.

35

No, sorry! I used the “Search your computer” app - the Dash? - and it came up with nothing for tificc or lcms. Neither did the Ubuntu Software app show anything installed. But I can see it’s there now I’ve done the command. Thanks again.

36

Those apps are CLI too, they probably won’t show in the dash search.