Use RT_Medium_gsRGB and let your printer know that you’re using the AdobeRGB colorspace.
http://rawpedia.rawtherapee.com/Color_Management#Output_Profile
Thanks! I didn’t know ImageMagick could do that.
Here are two more ways to retrieve an ICC profile that’s embedded in an image file:
Using a recent version GIMP 2.9, open the image and do “Image/Color Management/Save Color Profile to File” - this can handle V2 and V4 profiles and works with any file format that GIMP can open (which is to say, a lot of different file formats).
Using ArgyllCMS “extracticc” (http://argyllcms.com/doc/extracticc.html) from the command line:
extracticc name-of-image-file name-you-want-to-give-to-extracted-icc-profile.icc
This requires either a jpeg or a tiff, and probably only works with V2 profiles.
How many printable colors exceed the sRGB color gamut depends on the printer and the paper (and no doubt on the number and quality of the inks, state of calibration of the printer, and so forth).
Here are some 3D gamut comparisons between sRGB and four photographic printer profiles using various papers:
http://ninedegreesbelow.com/files/srgb-vs-printer-profiles/sRGB-vs-Frontier-Glossy.x3d.html
http://ninedegreesbelow.com/files/srgb-vs-printer-profiles/sRGB-vs-Chromira-Matte.gam.x3d.html
http://ninedegreesbelow.com/files/srgb-vs-printer-profiles/sRGB-vs-Silver_Rag_Epson_9890.x3d.html
http://ninedegreesbelow.com/files/srgb-vs-printer-profiles/sRGB-vs-SilverRag_Epson_4900.x3d.html
What do you think? Are there any significant printable colors that exceed the sRGB color space?
The 3D gamut comparisons (made using ArgyllCMS) require a browser that supports X3DOM: » Browser support - x3dom.org
I forgot to say, the gamut views can be rotated so you can see the differences in color gamut coverage from all angles. The color gamuts are in the LAB color space. The white wire frame is the sRGB color gamut. The color areas are the comparison printer profile color gamut.
If you aren’t familiar with LAB, here’s a brief introduction:
Pictures of Color Spaces Inside CIELAB
I summarized the various ways of extracting and examining ICC profiles here:
http://rawpedia.rawtherapee.com/How_to_extract_and_examine_ICC_profiles
Feel free to copypasta.
Thanks @Elle ! So which output profile would you recommend ? The printer one or a large standard color profile ?
You didn’t ask me, but I will put in my $0.02.
It depends on how you will print the image.
If you are sending it to a commercial printer who provides a profile for their printer AND who will accept the image already converted to that profile’s color space, then using the printer profile for soft-proofing AND for output is the preferred method. Of course that option is not currently available in RT. Regarding this method, I strongly recommend reading this thread , particularly the posts by"digitaldog". Note what he has to say about commercial printers who provide a printer profile for soft-proofing, but insist that the image you send be in sRGB space.
If you are printing at home the choice of output profile will depend on what software you use to print. Can’t offer any advice there.
@mikesan summarizes the situation pretty well. The post he refers to is well worth reading. The best answer is “it depends” on the printer and the color gamut of the image, and also (as discussed in the luminous landscape forum) on what the place you send your image to be printed actually does with the file you send them.
If you take the time to look at the color gamut comparisons I put together showing various printer profile color gamuts compared to the sRGB color gamut (and really you should if you are interested in making prints), you’ll see that:
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Even the lowly Frontier printer can print blue-greens, greens, yellow-greens, yellows, and oranges that fall outside the sRGB color gamut.
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Compared to the Frontier printer, the Chromira printer can print a somewhat larger volume of colors in the same range.
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The Epson printers with Silver rag paper can print hugely more colors in the same range, plus they can print some reds and magentas that fall outside the sRGB color space.
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Where all the printer profiles fall short compared to sRGB is that sRGB holds brighter colors in the shadows and highlights, and this is especially true in the range of colors from red through magenta to violet-blue and blue. When using relative colorimetric intent, using black point compensation can sometimes help to bring the shadow colors into gamut. But bringing out of gamut highlights into gamut usually requires a bit of desaturation as well as lowering the image white point. And even with black point compensation, often you’ll need to desaturate the shadows to bring them fully into the printer’s color gamut.
One factor that hasn’t been addressed in this thread is the color gamut of the image itself, as compared to the color gamut of your chosen printer. If the image has colors that your chosen printer can print (and that you want to preserve in the final image to be printed), and these colors aren’t contained in the sRGB color space, then of course use a larger color space for editing. Otherwise those colors are clipped upon conversion to sRGB (assuming integer precision, unbounded floating point images changes this situation considerably).
As an example, this page has pictures in CIELAB space of clipped image colors upon conversion of a bright red flower from ProPhotoRGB to sRGB: Clipped colors from ICC profile conversions. I encourage you to make your own such CIELAB comparisons, so you have a better idea of what colors fit into which color spaces.
Another factor that the discussion in http://forum.luminous-landscape.com/index.php?topic=109714.0 touches upon is the color gamut of your monitor. Any color in your image that’s out of gamut with respect to your monitor will display as the nearest color your monitor can display. So soft proofing an image that has colors your monitor can’t display is problematic, though many people manage to still produce excellent prints under such circumstances.
The bottom of this page has pictures in CIELAB of several sample monitor profiles compared to sRGB: Your LCD monitor and the sRGB color gamut
I encourage you to make your own such comparisons using your own monitor profile, so you have a good idea of which colors your monitor can actually display, compared to whatever printer profile you might want to use, and whatever RGB working spaces you like to use.
In case anyone actually wants to make such color gamut comparisons, here are sample commands:
Make a “gam” file from a color profile such as sRGB or a printer profile or a monitor profile (iccgamut):
iccgamut -v -w -k -ir sRGB.icm
iccgamut -v -w -k -ir ClayRGB1998.icm
Make a “gam” file from an image file (tiffgamut - the image must be a tiff or a jpeg, and you have to tell tiffgamut what color space the image is in):
tiffgamut -v -k -ir ACES-elle-V2-labl.icc two-apples.tif
Compare two color gamuts (viewgam - can be color space to color space, color space to image, or image to image).
Here is a sample command for comparing the sRGB and ClayRGB1998 color gamuts, assuming you already have the “gam” files:
viewgam -i -cn -t0.5 -s ClayRGB1998.gam sRGB.gam -w sRGB-vs-ClayRGB1998
And here’s a link to the resulting 3D view of the two color gamuts:
http://ninedegreesbelow.com/files/srgb-vs-printer-profiles/sRGB-vs-ClayRGB1998.x3d.html
Here’s a sample command for comparing an image color gamut to a printer profile, assuming you already have the gam files:
viewgam -i two-apples.gam -cn -t0.4 MPL-Chromira-Matte.gam apples-chromira
Here’s a link to a 3D view of a sample image color gamut compared to a sample Chromira printer profile (the wire frame is the Chromira profile, the smaller solid color gamut is the image, which is a picture of two yellow apples sitting on a navy blue table cloth):
http://ninedegreesbelow.com/files/softproof-test/apples-chromira.x3d.html
As an important aside, there is no such thing as “the” Chromira or “the” Frontier or etc printer profile. As the Luminance Landscape discussion makes clear, these profiles are the result of actually profiling actual printers, and even “the same” printer will produce different results from profiling given things like age of the printer, it’s state of calibration, new ink lots, new paper lots, new profiling software, the operator’s knowledge level, and etc. I have verified this “not the same” by actually looking at some sample profiles, so this isn’t just theory.
Anyway, hope some of the above is helpful. But if you are looking for “do this to accomplish that”, then again, the answer is “it depends”. And so the best anyone can do is share insights into what actual commercial printing establishments actually do with your image files, which @mikesan has done, plus share some useful tools for exploring the relevant color gamuts so you can make an informed decision, which I have tried to do.
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