Topic: How to test if a print was made at 16 bit? (Read 43703 times)

digitaldog · « **Reply #180 on:** October 16, 2018, 04:08:07 pm »

Quote from: elliot_n on October 16, 2018, 03:31:48 pm

In none of my tests did I convert the document to 8 bit. I just toggled the 16 bit checkboxess in the print driver, and the 'Use Dither' checkbox in Photoshop's Color Settings.

Well I think you should. The check box is very suspicious and doesn't live in the P800 driver or other drivers so I'd suggest you convert.
I'd also suggest you utterly ignore the Dither options unless we hope to only discuss Photoshop. What other products provide such an option? Not Lightroom (which needs testing), among many others. Lastly, as Adobe clearly shows in the Color Settings, Dither should only affect 8-bit per color data. IF it affects 16-bit data, it's a bug.

digitaldog · « **Reply #181 on:** October 16, 2018, 04:09:46 pm »

Quote from: faberryman on October 16, 2018, 03:44:06 pm

And why uncheck 16-bit? I mean turn it off to do the test, but check the box when you are actually printing.

If you're asking me, I turned it off WITH 16-bit data to see if it did anything with actual 16-bit data. It did absolutely nothing. It's not an option on my other printer and appears to be unnecessary; 16-bit data printed as expected with no such option.

faberryman · « **Reply #182 on:** October 16, 2018, 04:25:49 pm »

So checked or unchecked?

digitaldog · « **Reply #183 on:** October 16, 2018, 04:27:58 pm »

Quote from: faberryman on October 16, 2018, 04:25:49 pm

So checked or unchecked?

Checked or uncheck WHAT?

faberryman · « **Reply #184 on:** October 16, 2018, 04:28:51 pm »

16-bit.

elliot_n · « **Reply #185 on:** October 16, 2018, 04:29:15 pm »

Quote from: digitaldog on October 16, 2018, 04:08:07 pm

Well I think you should.

It didn't strike me as being relevant. I'm only interested in the effect of the print drivers' 16 bit checkboxes (there are two) on the printing of a 16 bit file.

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The check box is very suspicious and doesn't live in the P800 driver or other drivers so I'd suggest you convert.

I don't think it's suspicious. It does what it says it does.

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I'd also suggest you utterly ignore the Dither options unless we hope to only discuss Photoshop.

The 'Use Dither' setting is an integral part of the equation.

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What other products provide such an option? Not Lightroom (which needs testing), among many others.

I'm only interested in Photoshop.

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Lastly, as Adobe clearly shows in the Color Settings, Dither should only affect 8-bit per color data. IF it affects 16-bit data, it's a bug.

You're correct to the extent that if the entire pipeline is 16 bit, Dither won't be invoked. However, if you uncheck '16 bit' in the print driver, then the 16 bit file is converted to 8bit, and Dither is important in this conversion process.

digitaldog · « **Reply #186 on:** October 16, 2018, 04:36:09 pm »

Quote from: elliot_n on October 16, 2018, 04:29:15 pm

It didn't strike me as being relevant. I'm only interested in the effect of the print drivers' 16 bit checkboxes (there are two) on the printing of a 16 bit file.

It didn't do a damn thing on this end. ON, or OFF, with 16-bit data, I get the SAME results. I also get the same results in the P800 which has NO such options.
You think that if you take 16-bit data and turn the check box off, something converts it to 8-bits per color? That's absolutely not what I see testing with a 3880 on this end. And why assume it does? Convert the data to 8 bits per color THEN make a print. There's zero question it's 8 bits per color now. I see the difference too, on screen which I reported for those who read what I reported.

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I don't think it's suspicious. It does what it says it does.

What do you think it does? Why do I see zero difference if it's on or off?

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The 'Use Dither' setting is an integral part of the equation.

What equation would that be? Considering there are many, many applications for printing that have no such options, why would it be at all pertinent? And you don't seem to believe either Doug or I or Adobe who clearly show that dither in Photoshop alone is for 8-bit per color data, NOT 16-bit data.

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I'm only interested in Photoshop.

Terrific, you're not the only one here and the only one printing solely in Photoshop, that's WHY ACPU was discussed.

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You're correct to the extent that if the entire pipeline is 16 bit, Dither won't be invoked.

I know.

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However, if you uncheck '16 bit' in the print driver, then the 16 bit file is converted to 8bit, and Dither is important in this conversion process.

ONLY if you assume turning it off produces 8-bits per color with just that setting which doesn't jive with what my prints show. Or that many applications have no such option for Dither. Or that if you're printing 16-bit, as the OP who left asked about, Dither does absolutely nothing.

digitaldog · « **Reply #187 on:** October 16, 2018, 04:37:32 pm »

Quote from: faberryman on October 16, 2018, 04:28:51 pm

16-bit.

See my last post.

digitaldog · « **Reply #188 on:** October 16, 2018, 04:41:05 pm »

Quote from: elliot_n on October 16, 2018, 04:29:15 pm

I'm only interested in the effect of the print drivers' 16 bit checkboxes (there are two) on the printing of a 16 bit file.

Two, where? What print driver? I see simply one on my 3880n driver.

Alan Goldhammer · « **Reply #189 on:** October 16, 2018, 04:41:56 pm »

It very well could be that the 16 bit check box was an Easter Egg gone wrong.

elliot_n · « **Reply #190 on:** October 16, 2018, 04:42:24 pm »

Andrew, we've done the same test and got different results. I will redo my tests to double check. I don't think anything I am saying contradicts what Doug has already said.

digitaldog · « **Reply #191 on:** October 16, 2018, 04:44:24 pm »

Quote from: elliot_n on October 16, 2018, 04:42:24 pm

Andrew, we've done the same test and got different results. I will redo my tests to double check. I don't think anything I am saying contradicts what Doug has already said.

Back up, you say you see TWO check boxes. I see ONE. I don't recall what printer you're using. So please indicate what printer and where you see two 16-bit check boxes. With the ONE I see for my 3880, toggling it on or off makes no difference in the print when the data is indeed 16-bit. We may be getting differing results from differing drivers but until I know what you're doing and where, I can't comment further.

elliot_n · « **Reply #192 on:** October 16, 2018, 04:48:16 pm »

Epson 3880. OSX (High Sierra). Photoshop CS6.

Two 16 bit checkboxes:

Doug Gray · « **Reply #193 on:** October 16, 2018, 05:22:47 pm »

When I created Bills Black Ball, I first ran a dE00 on 1 bit changes from 0 to 255 in ProPhoto and selected the dark range that also had the largest dE00 for each bit increase. I used ProPhoto RGB because it has a 1.8 gamma which is a somewhat better match for the many different printer profiles I've examined.

However, I've been looking at the math and perceptual sensitivity v step size area and I should be able to produce an image that brings out the 8bit/16bit difference even better on prints. I'm also looking at doing an optimal version specifically for monitors to make it easier to test whether people's 30 bit system is really performing or has, without warning, reverted to 24 bits.

Alan Goldhammer · « **Reply #194 on:** October 16, 2018, 05:26:36 pm »

Quote from: elliot_n on October 16, 2018, 04:48:16 pm

Epson 3880. OSX (High Sierra). Photoshop CS6.

Two 16 bit checkboxes:

One is the PS dialogue box and the other is the Epson driver box. Different boxes for different purposes.

elliot_n · « **Reply #195 on:** October 16, 2018, 05:40:09 pm »

Quote from: Alan Goldhammer on October 16, 2018, 05:26:36 pm

One is the PS dialogue box and the other is the Epson driver box. Different boxes for different purposes.

Yes, you're right. I misunderstood the functions of those two dialog boxes.

Sorry, Andrew, your results now make sense to me.

However, it seems that there is one test you didn't do - printing the 16 bit file through ACPU with 16 bit unchecked. When I do this, I get banding in the print. This seems to contradict your conclusion that 'the check box doesn't do anything' (?)

digitaldog · « **Reply #196 on:** October 16, 2018, 05:43:50 pm »

Quote from: elliot_n on October 16, 2018, 04:48:16 pm

Epson 3880. OSX (High Sierra). Photoshop CS6.

Two 16 bit checkboxes:

Ah, the very old' CS6; no wonder; I'm on CC2019.

Only one of those is in the print driver. The other is Photoshop itself. I didn't mess with the Photoshop area whatsoever.

digitaldog · « **Reply #197 on:** October 16, 2018, 05:46:07 pm »

Quote from: elliot_n on October 16, 2018, 05:40:09 pm

However, it seems that there is one test you didn't do - printing the 16 bit file through ACPU with 16 bit unchecked.

I don't see the point. I was interested in seeing IF ACPU did pass the 16-bit data or not, seems it did.

digitaldog · « **Reply #198 on:** October 16, 2018, 06:52:41 pm »

Quote from: digitaldog on October 16, 2018, 03:00:42 pm

Next I printed the 16-bit document in ACPU. No profile of course. I see NO banding.

Decided this wasn't as clean a test as possible. The other tests, Doug's image was converted to the output color space through PS. Now while we'd not do this with ACPU, figured I'd give that a shot.
Converted to my custom profile (RelCol) in Photoshop using Convert to Profile. Again, Dither is off but shouldn't make any difference.
Opened the converted copy above in ACPU. For fun, I actually kept the 16-bit check box OFF in my Epson 3880 driver. The print isn't as dark this time because it was converted like the others.
Smooth as a baby's back end again. Like the others printed through Photoshop.
Conclusion: ACPU accepts 16-bit data and uses it. Further, the check box for 16-bit in the Epson print dialog doesn't do squat.

elliot_n · « **Reply #199 on:** October 16, 2018, 07:51:07 pm »

I repeated my tests.

I am seeing banding, admittedly subtle, when the image is printed with 16 bit unchecked in the Epson print driver*. There is no banding when 16 bit is checked.

I see this when printing from Photoshop, and also when printing from ACPU.

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* When printing from Photoshop, I have 'Send 16-bit Data' checkbox in the Photoshop print dialog checked. I am toggling the '16 Bit Output' checkbox in the Epson print driver.

Author Topic: How to test if a print was made at 16 bit? (Read 43703 times)