When you select Colour Management -> Profile -> "Managed by Printer", in what colour space does LR Classic send the image data to the printer?
I've searched the documentation, and I can find only (https://helpx.adobe.com/lightroom-classic/help/print-job-options-settings.html ) "To send the image data to the printer driver without first converting the image according to a profile, choose Managed By Printer."
Fine, but without converting the image from what? LR uses internally a variety of colour spaces, including
I can't find any statement about which is used in this case. Obviously, the printer driver needs to know the colour space of the image if it is to colour manage correctly.
The question arose on dpreview, and I realised I simply don't know the answer.
You should not be allowing managed by printer, you should be using an icc profile. When you allow managed by printer, colour management is lost.
Thanks for your posts and link. I agree with your posts about using colour managment by LR (and it's what I always use). And I do know what colour mangement is and does.
I probably didn't make my question clear. One should be able to do colour managment either in the printer driver or in LR. Most printer drivers for photo printers support colour management, and you can specify an icc profile in driver settings. So either you can do colour management in LR, and turn off colour management in the printer driver, or you can do colour management in the printer driver, and turn it off in LR (by setting "Managed by printer"). That option doesn't mean "no colour management"; as it says, it means colour management by the printer (i.e. the printer driver).
You have the same choice in Photoshop: in the Color Management section of the Print dialogue, you can choose "Printer Manages Colors" or "Photoshop Manages Colors". If you take the former choice, then it's clear that Photoshop will send the image to the printer in the current Working Space (which you set in Edit -> Color Settings). I think that's what LR does, and LR's Working Space is always ProPhoto RGB (but with linear TRC).
The problem is that LR and its documentation don't actually say what colour space is used when sending data from LR to the printer when you use "Managed by printer". It appears to be ProPhoto RGB / Linear, but I can't find that stated definitively.
It's rather hypothetical: I always use colour management by LR, not the printer driver, but the question arose in a recent dpreview thread, and I'm curious!
Again, thanks for your answers.
As for conversion, well no conversion , no new copy, just a translation, as defined in the icc profile, not as defined by LrC code.
icc profile for specific printer, specific paper, and sometimes for specific ink (not common)
And some icc profiles for specific look (typically from third party, no, I do not have an example)
When LrC is set to 'Managed by Printer' the application tags the image with the appropriate colour space (i.e. LrCs internal colour space). The printer driver then does the necessary colour space conversions. Photoshop handles 'Printer Manages Colour' in the same way.
Thanks! If by "the appropriate colour space" you mean "ProPhoto RGB with linear TRC" (which I believe is always LR's working colour space) then that's what I assumed, but couldn't find it documented.
Taking this discussion to the next event in processing, at so point either the Print Driver and/or Printer needs to convert to CMYK which has a smaller gamut that any of the other colour spaces. So, does it really matter?
I think it matters to the extent that the printer driver must convert to to some CMYK space (or some other subtractive space) from the space in which the data is sent to the driver. It needs to kow what that space is!
Actually, the gamut of subtractive spaces may be larger than that of typical RGB spaces at low luminance levels.