How to test if a print was made at 16 bit?

[Alan Goldhammer]

Why do you say that only 8-bit printing is supported. Maybe without a checkbox, 16-bit is now always selected.

It was my understanding from some posts on LuLa several years ago when this topic was discussed and the point was made at that time that WinOS only supported 8 bit printing.  As I noted in my previous post, there is no check box for 16 bit printing in the Epson driver for WinOS that I use (and it is the most current driver). 

Earlier thread:  https://forum.luminous-landscape.com/index.php?topic=89357.0

[elliot_n]

Why do you say that only 8-bit printing is supported? Maybe without a checkbox, 16-bit is now always selected. That certainly makes more sense. There never was any good reason to uncheck the box to begin with.

As I understand it, Epson's replacement for the 3880, the P800, no longer has a 16 bit checkbox on MacOS. I think with that set-up, it is valid to ask whether 16 bit is selected by default (for the reasons you state).

[Garnick]

As I understand it, Epson's replacement for the 3880, the P800, no longer has a 16 bit checkbox on MacOS. I think with that set-up, it is valid to ask whether 16 bit is selected by default (for the reasons you state).

Interestingly, the P7000 initially used a driver version that dates back to Mavericks at least.  When I upgraded to High Sierra about 6 months ago the first thing I did was check the Epson site for a new driver for the P7000.  At that point it was still the same driver I had already installed (v9.89) and it still works very well.  When Andrew mentioned a few days ago that the "P" series drivers now have no 16Bit availability I immediately checked my driver and it still has the 16Bit checkbox, which I have never used.  I was about to question Andrew on that but decided to first check the Epson site again.  Low and behold there was a shinny new driver for my P7000, which I downloaded but have not yet installed.  I will install the new driver on a Boot-Clone drive and test it before I apply it to my Main Work Drive, a procedure I always follow when upgrading any very important app.  I expect that the new driver will not include the availability of 16Bit printing, which I will not miss at all.

Gary 

[Mark D Segal]

As I displayed many posts back, the SC-P5000 driver for Mac does have the 16-bit option in the Printer Settings tab. It is therefore likely that the sister models (SC-P7000/9000) also have it. But you'll see soon Gary. I have no idea about the set-up for Windows - nothing in the product manual for Printing with Windows mentions it.

[Doug Gray]

This is not how it works on a mac.

With ACPU and an Epson 3880 there is a 16 bit checkbox. One can thereby choose between an 8 bit or a 16 bit print pipeline.

With the 8 bit pipeline, your ball image prints with visible banding (subtle, but clearly visible under a bright light - no need to trim off the prints white edges). With the 16 bit pipeline the image prints smoothly.

Good to know that it works on a Mac. Or at least that one. It indicates ACPU likely does not automatically convert 16 bits to 8 before printing and when it appears to do so the problem is elsewhere. It's likely ACPU source code is not doing it. Thanks for testing it!

[felixpq]

Here something to reflect on for all of us I would assume. The quote is from (Graeme Gill)

"If you assume that the gamut of a printer roughly spans 150 delta E units, then 8 bit precision amounts to 0.6 delta E if the space was perceptually uniform. So you might aim for a measurement precision of 0.2 delta E or better, so as to be able to distinguish 0.6 delta E steps."

A true 16 bit pipeline would imply something in the order of 0.002 to 0.005 DE range which is mostly likely beyond the range of most instrument to begin with. Based on that I'll let you draw your own conclusions.

That's all for me on this subject.
YG
 

[Doug Gray]

Here something to reflect on for all of us I would assume. The quote is from (Graeme Gill)

"If you assume that the gamut of a printer roughly spans 150 delta E units, then 8 bit precision amounts to 0.6 delta E if the space was perceptually uniform. So you might aim for a measurement precision of 0.2 delta E or better, so as to be able to distinguish 0.6 delta E steps."

A true 16 bit pipeline would imply something in the order of 0.002 to 0.005 DE range which is mostly likely beyond the range of most instrument to begin with. Based on that I'll let you draw your own conclusions.

That's all for me on this subject.
YG

It's very much a function of the printer's device space. Printers are typically pretty non-linear over their space and what happens is the average dE00 doesn't change much for in-gamut colors but you get some areas where the printer has 8 bit space steps that exceed 1 dE00 while the large majority are under .4 dE00. By analyzing a given printer's profile you can find the region that is most sensitive and can show banding in color areas. But those regions are small and the combination of factors required to produce visible results are such that it is likely very rare to ever encounter them even with synthetic images.

Banding seen in real life is a function of hitting gamut edges and how smoothly profiles transition requested colors at those edges where 8 bits or 16 bits is irrelevant. This is a function of the software that creates profiles and is to some degree an esthetic choice. This is the real value of images that stress printer/profile limits. It's the real value of images like Andrew Rodney's gamut test images.

[digitaldog]

For the Epson 3880 printing under WinOS with the most current driver, only 8 bit printing is supported.  There is no checkbox for 16 bit printing.  I cannot remember whether for THIS printer 16 bit printing is/was supported under MacOS.  It may be that the current Epson printers support 16 bit printing under WinOS but I don't have one of those.

Correct, I'm aware of that on Windows for the 3880 but I'm wondering about the newer printer Mark is using. On my Mac, P800, the option for 16-bit is gone now. But it's available on his newer printer. I was wondering if that's the case on Windows.

[Mark D Segal]

Correct, I'm aware of that on Windows for the 3880 but I'm wondering about the newer printer Mark is using. On my Mac, P800, the option for 16-bit is gone now. But it's available on his newer printer. I was wondering if that's the case on Windows.

I checked the Windows section of the SC-P5000 Manual and there is nothing said about a 16-bit checkbox for printing with Windows, so I assume the option is not provided in the Epson 5000 driver for Windows operating systems. Nor do I understand why the option should be provided on the 5000, but not on the 800. There has to be an explanation - I just don't know what it is!

[JRSmit]

Yeah. Mine prints 16 bit images too. Nothing I said suggests it doesn't print 16 bit images. It just converts them to 8 bits first and produces exactly the same banding as printing BillsBlackBall in Photoshop w/o dither and no color management to my 8 bit driver.

I just did it on my Windows 10 x64.

And selecting dither fixes it.

Keep in mind this is hard to see. You have to print the Ball out, trim the white edges, and view it under a strong light - a flashlight works pretty well. But only illuminate the print. if you have anything nearby that the strong light hits it will keep your eyes from adapting.

Recall that creating an image that can actually detect 16 bit v 8 bit printer paths is not easy. In fact the bands are only .4 dE00 apart. This is why they aren't normally visible. However, if you follow the instructions to remove the white borders and look at the print under a strong light, this has the effect of multiplying the dE00 separations and makes the banding visible. This is also why to check a monitor one has to get rid of the white background and ideally use a black one.

The dE00 metric assumes one is viewing two patches, close but not touching, against a neutral L*=50 background. The relative brightness overwhelms the banding. But viewing against a black background brings it out because the eye adapts to the lower illumination and smaller dE00s become magnified and visible.

But this is with Windows and it's possible the Mac ACPU differs.

Contrary tot Lightroom, when Printing from Photoshop the spoolfiles does not double in size. So yes i Think that PS is still 8bit of was when i tested this, about a year ago.

[digitaldog]

For Printers:
Print with a 8 bit driver using Null-Transform or RelCol on a glossy type paper or anything with Dmax of 2 or higher. Make sure the Edit->Photoshop->Dither option is off. It's best to print this w/o using color management using the Null-Transform technique but it can be printed normally too. The banding will be more regular with the Null Transform but will occur with both. You should then trim the white borders of the print and examine the print in a bright light. The banding will be quite obvious.

I just tried this test. First, awesome and useful new testing image (Bill's black ball).
I used an Epson 3880 on Mojave where one can select a 16-bit check box in the driver. I set the driver for 2880, finest detail is off.
I made the first print with check box on, 16-bit, used my output profile (cause why would I print without it and Doug said it's OK). This is premium luster. RelCol for RI.
I see NO banding.
I converted this to 8-bits per color in PS. I immediately see banding on-screen. Note I'm using a full high bit video path and display. I see the 'banding' (concentric circles) on the print under my GTI booth.
Next I printed the 16-bit image again as in step #1, the ONLY difference is, I turned OFF the check box in the 3880 driver. I see NO banding on the print, it looks just like print #1.
Conclusion: the check box doesn't do anything. Now I could be wrong, but print #1 and #3 look the same. The only difference is if the check box is on or off and the two prints are identical.
Next I printed the 16-bit document in ACPU. No profile of course. I see NO banding. Nothing like I saw in Photoshop printing the 8-bit per color doc. It's darker of course, no profile. But no concentric circles, smooth as a baby's behind.
Conclusion: It appears to me, ACPU does print 16-bit data.
Next I printed the image in 16-bit on my P800 again using my profile, RelCol etc. There is of course no check box in this driver.
I see NO banding.
Conclusion: Lack of check box doesn't affect the output of high bit data. Just as seen above with the 3880.
Dither was OFF in Photoshop for all testing.
Now the question is, does Windows do the same, can it pass the high bit data to the driver with or without a check box, that check box appearing on this end to do nothing at all.
Doug's test image appears to provide a good way to decide IF or IF NOT high bit data is passed to the driver or, the driver is doing something with that data that can be seen on output.

[Mark D Segal]

Very useful Andrew, at least answers the outcomes for OSX; but leaves open of course why they provide the option in the one printer but not the other, and what happens on Windows.

[digitaldog]

Very useful Andrew, at least answers the outcomes for OSX; but leaves open of course why they provide the option in the one printer but not the other, and what happens on Windows.

This indicates to me, the 16-bit check box is a marketing created option in the driver. Of course if anyone finds a difference in their testing, I'd love to know. I didn't try 8-bit per color with the check box on, seems pointless. And it makes sense that the driver wouldn’t need the check box as unseen on the P800. Not super happy Epson has some drivers with and some without the option or that the option even exists based on what I see. Which again is why I think the check box is almost certainly a marketing generated 'feature' and nothing more. 

[elliot_n]

Next I printed the 16-bit image again as in step #1, the ONLY difference is, I turned OFF the check box in the 3880 driver. I see NO banding on the print, it looks just like print #1.

I get banding in this scenario (with 16 bit unchecked, and 'Use Dither' in Photoshop's Color Settings unchecked). If 'Use Dither' is checked, there is no banding.

[digitaldog]

I get banding in this scenario (with 16 bit unchecked, and 'Use Dither' in Photoshop's Color Settings unchecked). If 'Use Dither' is checked, there is no banding.

NONE of my output testing as Doug indicated, had Dither on. Dither should play no role with high bit data.

[elliot_n]

So it's strange that we got different results.

[elliot_n]

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.

Printing from Photoshop I got banding when 16 bit was unchecked, but only if 'Use Dither' was also unchecked.

Printing from ACPU I got banding when 16 bit was unchecked.

[faberryman]

So I guess we should use "Use Dither" in its default setting of on. This doesn't sound like rocket science.

[faberryman]

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

[Doug Gray]

NONE of my output testing as Doug indicated, had Dither on. Dither should play no role with high bit data.

Right. Dither plays no role in 16 bits.