Simple printing feature

[Beep6581]

Originally reported on Google Code with ID 2652

I've just got my own photo printer, and I've started to dig into profile making with
Argyll etc.

Then I realized that it would be quite simple to introduce printing to RawTherapee,
we could do it in steps.

The first step would be to be able to produce TIF files ready for printing, RGB conversions
is good enough as most printers today are "fake" RGB devices, also the inkjets.

1. convert using a provided ICC profile, either with perceptual intent or relative
colorimetric with black point compensation.
2. scale the image to ideal printer resolution (usually 720, 360, 600 or 300 ppi)
3. optional print sharpening

Step 2 and 3 is not too important actually, the printer driver generally makes a good
job on scaling, and print sharpening is rarely needed (I think).

If you do it manually today you use "tifficc" from LCMS, or Argyll's own cctiff which
does the same, but cctiff lacks black point compensation, so I prefer tificc.

perceptual:
tificc -v -i <image file icc> -o <printer+paper icc> -t0 -w16 <input tif> <output tif>

relative colorimetric with BPC
tificc -v -i <image file icc> -o <printer+paper icc> -t1 -b -w16 <input tif> <output
tif>

All tifficc features are of course just simple LCMS API calls, so the API is already
there in RawTherapee.

The next step would be to actually send it to the printer driver, but I who run on
Linux like to be able to generate ready tif files too which I then just dummy-print
in Windows using the free Adobe Color Printer Utility, and then have some layout features.

First step suggestion:
* Current resize tool is used as scaling, no change required there to start with, but
we could add sharpening there later, and make it possible to set size in mm and set
PPI separately.
* In the color management tab add "Printer profile" below "Output profile", which contains
ICC selection, rendering intent, black point compensation on/off. I think we should
have all the rendering intent combinations available, a bit less user-friendly than
only two choices as in Lightroom, but RawTherapee should be a software where you can
experiment.
* Then how do differ between saving normal image and saving for print I'm open for
suggestions...

Reported by torger@ludd.ltu.se on 2015-01-31 12:25:44

[Beep6581]

Would be nice to have one!

I would like to be able to load a printer's ICC into RT and see what to expect in the
printout in the preview. Rendering intent, black point etc. would apply in real time
as any other tool. I don't think there should be anything special about this, not a
"mode", just load the ICC and see the print proof. All these print-proofing tools would
be at the end of the processing pipeline.

The crop tool needs improvement, there are multiple issues.

Sharpening after downscaling is issue 1358.

Storing processing settings for printing could be easily facilitated if issue 2624
- multi-PP3 support - was implemented.

Reported by entertheyoni on 2015-01-31 19:54:14

• Labels added: Type-Enhancement
• Labels removed: Type-Defect

[Beep6581]

First step suggestion:
* Current resize tool is used as scaling, no change required there to start with, but we could add sharpening there later, and make it possible to set size in mm and set PPI separately.

That is handled by #54