Of course it's possible, I didn't say otherwise. I said very, very few print drivers provide this data to be fully passed onto the printer. And I said, based on my testing of this, it's not at all useful; it's invisible!
My Epson 3880 driver (on Mac OS ONLY) has a check box for passing 16-bit data. Using this very wide gamut test file, filled with images and synthetic constructs, I sent the image to the driver in 16-bit. Then converted to 8-bit per color and turned the check box off to be sure. There is NO visible difference in the two prints under my best loupe. Nada, nothing, zero.
Try it for yourself using this test image:
http://www.digitaldog.net/files/Gamut_Test_File_Flat.tif
Now even more interesting is that my newer P800 driver no longer has this option (check box). What does that tell you?
Some Canon print drivers (the PS plug-in) also allow this option. So yeah, it's possible. And thus far, I've seen no one that has provided data it's at all necessary.
High bit data is about editing overhead. Then all you need to do is send the best 8-bits per color to the driver. And when you don't, most drivers convert the high bit data to 8-bits per data behind your back.
Thanks for the file, it seems super at first glance, I'm curious about one little thing though, at the top of the sheet it says ProPhoto RGB 16 bit data, so why the file profile is Adobe RGB?
I especially love this one, "... most drivers convert the high bit data to 8-bits per data behind your back." and it is exactly why I would like to be able to know if they did this to me or not?
When most people here say there is no visible difference between a 16 and a 8 bit print and suggest strongly don't waste your time on this, could it be because someone is playing in their back?
Since every one seems to agree that I waste my time and yours with my questions and that whether or not the companies do stuff behind our backs. You are correct in saying there is no noticeable difference but for the wrong reason unfortunately.
Here is an answer that everyone can verify probably even with a scanner, using the CIE76 Delta E metric and even considering that this metric is not uniform across the spectrum, ie we can see some color difference better then others and that I tested only a few RGB triplets by changing just on color by one 8 bit level say (100, 100,100) compared to (100,101,100), I converted each of those to (XYZ) and then to L*A*B* then applied both CIE76 Delta E and CIEDE2000 and the result are under the just discernible threshold according to my reference, in other words we can't see it. That being said, with an instrument like the I1Studio spectrometer or whichever, again this as to be taken with a grain of salt because we don't know what companies do in our backs and I didn't read all the fine print. The RGB triplets above give a DE2000 of about 1 unit, to be honest I used an Excel sheet to do these calculation and I don't know which colorspace these RGB values are treated as, nor the illuminant and which observer so your mileage will vary that's for sure. The good news is a spectrometer like the one in the I1Studio product can in theory measure a 0.1 DeltaE*2000 under an illuminant of D50 and assuming a 2 degrees observer. In other words if you have one of these to make your profiles you can check if you've been screwed or not.
Same goes for your supposedly 10 bit quasi full (95% plus) covering of the AdobeRGB gamut display, some companies play in your back here as well , I forgot many paper, ink and printer combo bust the AdobeRGB colorspace but it doesn't matter, no monitor is likely to show these color anyway and since you can't see them in your workflow, why bother. I think Ansel Adams wouldn't like this kind of thought but who knows.
Think of this, suppose that on this or that print, you have say in 16 bit a value just barely above the 8 bit level of say 100 and the value of next pixel to it is halfway between 101 and 102. According to most of what you say, in this situation your driver may very likely convert these 16 bit values to 100 and 101 and yes we won't see a noticeable difference we agree 100 % but at a true 16 bit values of 100 to 101 + 126/255 the Delta E increases by 50%, again it may not be noticeable visually. But it will at some point even if it's barely noticeable overall your image will definitely have smoother gradient at 16 bit then at 8 bit, it's a fact.
Have a nice day all and thanks for the inspiration.
