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Author Topic: 16 Bit B/W Printing  (Read 3438 times)
John R Smith
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« on: June 25, 2007, 09:05:28 AM »
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Fellow Printmakers -

As I understand it, printers such as my Epson R2400 convert any file to 8-bit greyscale before printing via the Advanced B/W Mode. Theoretically, there are then just 256 shades of grey available to describe the image. Are there any printers or RIPs which can handle 16 bit greyscale images? And if there are, is there any visible improvement in the output?

John
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and a case full of (very old) lenses and other bits
rdonson
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« Reply #1 on: June 25, 2007, 10:07:04 AM »
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Fellow Printmakers -

As I understand it, printers such as my Epson R2400 convert any file to 8-bit greyscale before printing via the Advanced B/W Mode. Theoretically, there are then just 256 shades of grey available to describe the image. Are there any printers or RIPs which can handle 16 bit greyscale images? And if there are, is there any visible improvement in the output?

John
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Windows print drivers are 8 bit so they convert any 16 bit data to 8 bit for the printer.

RIPs often offer 16 bit data paths since they don't use the manufacturer's print driver but the question becomes what do they do with it.  In color it offers smoother tonal changes.  

In b&w I'll defer to those with greater expertise but its long been thought that the human eye/brain can't discern more that 256 shades of gray anyway.

I think the real key in b&w isn't how many bits of data you're using its "how many shades of black do you have in your printer?"

You might want to check out something like Jon Cone's Piezography systems [a href=\"http://shopping.netsuite.com/s.nl;jsessionid=ac112b1b1f432e37cb610a8c4b5cb6ee9601cf1ea281.e3eTaxmKbNaNe34Pa38Ta38Max50?c=362672&sc=15]here.[/url]
« Last Edit: June 25, 2007, 10:11:38 AM by rdonson » Logged

[span style='font-size:14pt;line-height:100%'][span style='font-family:Arial'][span style='font-family:Geneva'][span style='font-size:8pt;line-height:100%']Regards,
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Bruce Watson
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« Reply #2 on: June 25, 2007, 02:43:51 PM »
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I print with an Epson 7600 using Cone's PiezoTones and StudioPrint. StudioPrint handles 16 bit files, so I skip the step in output of converting my file down to 8 bits. To see if it matters, I've run this experiment a couple of times.

Take a 16 bit file, do all your edits. At print time I send the 16 bit file to StudioPrint to print. While the printer is busy with that, I convert this file to 8 bits and print that when the first print is done. Put them up side-by-side on my "proofing wall" under the same lights.

Personally, I can't tell the difference. Everything I've read says that the human visual system can't identify anything close to 256 individual grays, so this result isn't surprising on that level. I would have thought that the extra grays in the 16 bit files would make for smoother transitions thought, and I don't see that either. Both prints have the same silky smoothness.

For what it's worth...
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John R Smith
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« Reply #3 on: June 26, 2007, 05:20:06 AM »
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So then, the concensus would be that there are worthwhile gains to be had from editing a B/W file in 16 bit space, but no discernible differences when printing (if a 16 bit print driver was available).
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and a case full of (very old) lenses and other bits
Geoff Wittig
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« Reply #4 on: June 26, 2007, 05:46:23 AM »
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This seems to be the standard conclusion. For what it's worth, Bill Atkinson advocated using a Photoshop action to prepare edited files for printing by flattening the layers and dropping to 8 bits, since this reduced the amount of data being sent to the printer and sped up the process without any visible effect on print quality.
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Ernst Dinkla
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« Reply #5 on: June 26, 2007, 06:26:03 AM »
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This seems to be the standard conclusion. For what it's worth, Bill Atkinson advocated using a Photoshop action to prepare edited files for printing by flattening the layers and dropping to 8 bits, since this reduced the amount of data being sent to the printer and sped up the process without any visible effect on print quality.
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To add to that advice: I think there could be an advantage when the conversion to printer profile is done in 16 bits if one uses profiling before the B&W print. Depends on the driver/RIP whether that is done at 16 bit normally and the quality of the profile. While it is doubtful whether we can see an 8 bit tone range on paper in reflecting light and it is also not so evident all B&W prints have a tone range like that, it would be bad if several 8 bit steps in the process resulted in losing one of the 255 tone steps. The profiling step could be like that. In the 8 bit (in-output) drivers some 16 bit calculations are quite common to avoid similar rounding off errors.

Ernst Dinkla

www.pigment-print.com
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neil snape
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« Reply #6 on: June 26, 2007, 06:43:04 AM »
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Let's just separate image bit depth and rasterise bit depth.
For B&W I can't really see why more shades of grey would produce anything quite different between 8 or 16 bit.

Yet there is a lot of difference between masking done at 16 bit before sending to the printer. HP's 9180 driver is full 16 bit screening which is easily shown to be better on B&W to those who know what they are looking for.
Too bad it is only for the humble 9180.
I think the Epson printers with variable drop are very good at screening to albeit a lower bit depth. It will be nice to see what variable droplet size would be like with 16 bit screens.
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TylerB
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« Reply #7 on: June 26, 2007, 11:52:10 AM »
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...
I think the Epson printers with variable drop are very good at screening to albeit a lower bit depth. It will be nice to see what variable droplet size would be like with 16 bit screens.
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Reliable rumor has been around for some months that there will be 16 bit Epson drivers. Exactly what that means and how it makes use of the data, and whether or not it results in actual 16 bit screens will probably remain proprietory. StudioPrint takes 16/channel in, who knows how it's used?
This is one of those issues that is hard to address, I suspect you will rarely if ever see a different on paper, until that magic alignment of the image, stars, and your mood, suddenly makes the difference appear.
I would think single channel (several B&W methods) would reveal a difference before color, where other channels/inks will mask an individual channels "problems".
Interestingly, IJC/OPM, an advanced B&W driver based on GIMP code, insists they take 16 bit in, and make use of it.
There seems to be little user talk about the Canon export module with this regard, that I have seen.
Tyler
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neil snape
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« Reply #8 on: June 26, 2007, 02:58:03 PM »
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I think GIMP or rather Gutenprint has phenominal things inside. You can drw your own screens, change separation settings, run full 16 bit images and high bit screening. Most of the developers know this and sometimes play in there too just to see what raw output is on various machines. Yet for the casual user we are restricted to the OEM driver or a RIP that has some rich features such as ImagePrint with 16 bit imagery with high bit screens that go well beyond the driver.
Canon had to make a driver plug in to get there, but with Vista and Os X.5 the fundamental architecture, I'm told is set for 16 or even 32 bit drivers.
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