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Author Topic: Clarification on Print Resolution  (Read 62980 times)
BartvanderWolf
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« Reply #140 on: June 21, 2011, 02:33:22 AM »
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To answer Bart - as I said originally, there's no particular downside except for longer processing times, for real world images.

Indeed, that seems to be the consensus amongst those who have tested it, although Jeff seems to have another opinion based on something that was told to him. That's why I asked him if his position was also based on personal observation, which it apparently isn't.

Which raises another question, since Jeff was involved in structuring the most recent LR output logic/workflow, why let Lightroom upsample to 720 PPI (assuming that is what it does when instructed to do so), and let the printer driver downsample to 360 PPI ? All the empirical evidence I've seen, and heard being described by others (including Eric Chan and Mike Chaney), indicates that resampling (up or down) to 360 PPI is happening unless the Finest Detail option is set, as witnessed by aliasing artifacts which would not be generated by dithering alone.

Cheers,
Bart
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Farmer
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« Reply #141 on: June 21, 2011, 02:47:16 AM »
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Gromit - yes, but that's not changing the input resolution.
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Shane Webster
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« Reply #142 on: June 21, 2011, 11:23:48 AM »
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John,

I did print the full test chart at 720.  Living in the land of inches, I could never get an exact size within LR to print at 720 so I adjusted the canvas size (not image size) in PS to even numbers, went back to LR, set the cell size and printed (LR was reporting the image at 720).  While I'm fairly certain there was a difference in line thickness between 360 and 720's Column D, I need to pull the print and look.  I've been out of pocket since yesterday afternoon, but will look at it either this evening or in the morning and post the result.
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Schewe
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« Reply #143 on: June 21, 2011, 11:33:08 AM »
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Indeed, that seems to be the consensus amongst those who have tested it, although Jeff seems to have another opinion based on something that was told to him. That's why I asked him if his position was also based on personal observation, which it apparently isn't.

Always happy to learn something...I tried printing out on my 4900 with and without Finest Detail selected. With an image at 720 PPI, I can see a tiny improvement in high frequency image data when the Finest Detail option is selected. So, it looks like I'll be selecting that option when printing on printers that offer it–which is the Epson pro line.

The R3000 that I have does not offer that option. It does have two different 1440 dpi settings; SuperFine and Photo. The settings I've been using with that printer is SuperPhoto which states 5760 dpi.
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Mark D Segal
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« Reply #144 on: June 21, 2011, 11:39:00 AM »
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Always happy to learn something...I tried printing out on my 4900 with and without Finest Detail selected. With an image at 720 PPI, I can see a tiny improvement in high frequency image data when the Finest Detail option is selected. So, it looks like I'll be selecting that option when printing on printers that offer it–which is the Epson pro line.

The R3000 that I have does not offer that option. It does have two different 1440 dpi settings; SuperFine and Photo. The settings I've been using with that printer is SuperPhoto which states 5760 dpi.

Great - glad you did that Jeff.
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Mark D Segal (formerly MarkDS)
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John R Smith
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« Reply #145 on: June 21, 2011, 12:37:14 PM »
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I did print the full test chart at 720.  Living in the land of inches, I could never get an exact size within LR to print at 720 so I adjusted the canvas size (not image size) in PS to even numbers, went back to LR, set the cell size and printed (LR was reporting the image at 720).

Shane, you can't set the cell size in LR accurately enough if you have the measurements set in inches. A hundreth of an inch is bigger than a hundreth of a centimetre - 2.54 times bigger. You have to select the metric option in order to alter the cell size in small enough increments to get exactly 720 ppi for the test. Check your output in column D with a decent loupe.

John
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BartvanderWolf
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« Reply #146 on: June 21, 2011, 12:41:59 PM »
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Always happy to learn something...I tried printing out on my 4900 with and without Finest Detail selected. With an image at 720 PPI, I can see a tiny improvement in high frequency image data when the Finest Detail option is selected. So, it looks like I'll be selecting that option when printing on printers that offer it–which is the Epson pro line.

Hi Jeff,

That's good news. Who would say no to better quality at a price that cannot be beat? One more item that can be eliminated from the QED list. I assume you tested with Lighroom 3, which would mean that selecting the 720 PPI option there now really results in 720 PPI detail without downsampling by the printerdriver to 360 PPI, if available. Did you notice any adverse effects as alluded to by the Epson enigineer? Maybe that only happens in very rare and specific/theoretical scenarios?

Cheers,
Bart
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Schewe
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« Reply #147 on: June 21, 2011, 12:46:14 PM »
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I assume you tested with Lighroom 3, which would mean that selecting the 720 PPI option there now really results in 720 PPI detail without downsampling by the printerdriver to 360 PPI, if available.

Correct...

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Did you notice any adverse effects as alluded to by the Epson enigineer? Maybe that only happens in very rare and specific/theoretical scenarios?

Well, my test was really only a few prints with and without Finest Detail checked so I would NOT call that exhaustive. I'll be seeing some of the Epson people next month and see if I can drill down on the Finest Detail setting.

Note, edited my response to add the word "NOT"
« Last Edit: June 21, 2011, 02:03:51 PM by Schewe » Logged
Mike Guilbault
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« Reply #148 on: June 21, 2011, 12:53:16 PM »
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So... any chance we can have a summary of what's been discussed here?

It sounds like, for Epson printers, if the image resolution is below 360, then use a Print Resolution of 360 (in LR).  Finest Detail won't have any benefit at this resolution. If IR is above 360, then use a PR of 720 and turn on Finest Detail.  Yes? No?  I know... it depends!
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John R Smith
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« Reply #149 on: June 21, 2011, 01:16:35 PM »
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So... any chance we can have a summary of what's been discussed here?

How did you like your thread, Mike? It got quite good, didn't it  Wink As for a summary, we're still in the thick of it here . . .

Seriously, as far as I can see yes it still all depends - on your output software, your printer model, and just as important the size of print you are making and whether that involves up or down-sampling to achieve that size on paper. The rule of thumb which Jeff set out at the beginning is still a good one in general, for LR and Epson printers. The debate has been about why it works, not whether it works. However, in some cases as we have seen with my R2400, you would probably be better off sending all your print data whatever size print at 720 ppi, otherwise it could be resampled twice (not a good thing). And the only way to be sure about this is to thoroughly test your own printer and software combination. As Mark said, you have to trust your own eyes.

John
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BartvanderWolf
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« Reply #150 on: June 21, 2011, 01:23:01 PM »
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Well, my test was really only a few prints with and without Finest Detail checked so I would call that exhaustive. I'll be seeing some of the Epson people next month and see if I can drill down on the Finest Detail setting.

Great, that's most helpful. Do not hesitate to also raise the issue of resampling to 360 or 720 PPI, versus dithering. All the effects we can see point to resampling, but it's all based on the resemblance of the artifacts with those from resampling. Although unlikely, it might well be something different and only they can know for sure.

Cheers,
Bart
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Mike Guilbault
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« Reply #151 on: June 21, 2011, 04:52:03 PM »
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How did you like your thread, Mike? It got quite good, didn't it  Wink As for a summary, we're still in the thick of it here . . . John

Quite good doesn't quite cover it John. I've learned a lot - much of it is still over my head - but I think it's sinking in.  That's why I asked for the summary. Wink

So, just to be sure I have the test right, I should try a Print Resolution (set in LR Print module) of 720 with Finest Detail On, and Off as well as the 360 setting to see what's best for my combination?

Now,lets say I get the best results at 720 with Finest Detail on... would there be a problem with using this setting all the time? I realize there may not be a visible difference, but if it doesn't lower the quality, then I shouldn't have to do a test for each image that I want to print. 
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Schewe
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« Reply #152 on: June 21, 2011, 05:11:49 PM »
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Now,lets say I get the best results at 720 with Finest Detail on... would there be a problem with using this setting all the time? I realize there may not be a visible difference, but if it doesn't lower the quality, then I shouldn't have to do a test for each image that I want to print. 

No currently known downside other than slightly slower spooler processing and printing.
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Mike Guilbault
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« Reply #153 on: June 21, 2011, 05:51:07 PM »
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Slightly slower doesn't bother me for this type of printing so that's good to know.

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Schewe
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« Reply #154 on: June 22, 2011, 01:19:04 AM »
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Do not hesitate to also raise the issue of resampling to 360 or 720 PPI, versus dithering.

At this point it's unclear if or when any upsampling occurs on Mac and Windows. There's some indication that with older print pipelines the device driver reported a "device resolution" to the system level OS print pipeline. I think that the older (meaning pre Win 7 and Carbon based on the Mac) pipeline "assumed" that the image data passed to the print driver needed to be a specific resolution based on what the devise was "asking for" (meaning, reporting to the OS). Whether or not the system level print pipeline resampled image data and the manner of the resampling is unclear.

I'm still kinda sticking to the statement that the print driver for Epson doesn't resample the image data line for now. I'm now thinking it's possible that somewhere in the print pipeline some sort of resampling gets done. What not clear is where the resampling may be done nor the manner of the resampling (flavor of the algorithm).

What is clear is that with regards to Lightroom and Epson pro printers, doing the upsampling to 360/720 (depending on the native resolution of the file) and then choosing the correct driver settings (Finest Detail off if upsampling to 360 from below 360 native rez and Finest Detail on if upsampling to 720) will produce the finest image detail in the print.

Eric Chan is somewhat involved in the discussion and so is the engineer for Photoshop. I'm also pushing this up the pole to people at Epson (I have zero contacts at HP & Canon) to get some sort of official response. I will say that my contacts at Epson are of course, very interested in advancing the art of printing to Epson printers. If it turns out that we can recommend a new "best practices" to them, they'll adopt it. Of course it'll take a while to trickle down to manuals and such. But there may be a "white Paper" that could be released that gives a definitive answer.

For now the essence is for Epson pro printers, if the native resolution of the image size is below 360, upsample to 360 and don't select the Finest Detail setting in the driver. If the native rez is above 360 but below 720, resample to 720 PPI and make sure to select the Finest Detail option. Presumably for Canon and HP the magic numbers are 300/600. But I have zero experience in configuring HP or Canon print drivers so you'll need to test this out for yourself.
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BartvanderWolf
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« Reply #155 on: June 22, 2011, 03:33:03 AM »
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[...]
What is clear is that with regards to Lightroom and Epson pro printers, doing the upsampling to 360/720 (depending on the native resolution of the file) and then choosing the correct driver settings (Finest Detail off if upsampling to 360 from below 360 native rez and Finest Detail on if upsampling to 720) will produce the finest image detail in the print.

Indeed, by sending resampled (to 360/720 PPI) data to the printer, we can make sure that the printer or printer driver don't do that. All risks are eliminated, and the sending application has full control over the quality of resampling and can do sharpening at that final resolution. All that people need to be aware of is that selecting borderless printing will again invoke a re/upsampling operation with a variable amount (and thus sensitive to the unknown quality of that resampling).

Quote
Eric Chan is somewhat involved in the discussion and so is the engineer for Photoshop. I'm also pushing this up the pole to people at Epson (I have zero contacts at HP & Canon) to get some sort of official response. I will say that my contacts at Epson are of course, very interested in advancing the art of printing to Epson printers. If it turns out that we can recommend a new "best practices" to them, they'll adopt it. Of course it'll take a while to trickle down to manuals and such. But there may be a "white Paper" that could be released that gives a definitive answer.

Great, that's helpful. Thanks for your cooperation.

Quote
For now the essence is for Epson pro printers, if the native resolution of the image size is below 360, upsample to 360 and don't select the Finest Detail setting in the driver. If the native rez is above 360 but below 720, resample to 720 PPI and make sure to select the Finest Detail option. Presumably for Canon and HP the magic numbers are 300/600. But I have zero experience in configuring HP or Canon print drivers so you'll need to test this out for yourself.

Canon/HP printers sofar usually default to 300/600 PPI with the appropriate driver settings for paper and quality. Programs like Qimage report back what the printer driver expects as input, and on-the-fly automatically adjusts its resampling and smart sharpening to that final output size. So if a specific printerdriver setting would require/allow anything different, it will be taken care of automatically. The user is given control over the amount of smart sharpening, and that's all that's needed because it will allow to adapt to different print media.

So, unless the printer manufacturers can point out any drawback for this safe practice of requested resampling and sharpening before sending to the printer(driver), it would seem a logical move for the software developers to optimize the workflow and quality at their end, based on what the printer driver reports to expect.

Cheers,
Bart
« Last Edit: June 22, 2011, 03:37:56 AM by BartvanderWolf » Logged
Shane Webster
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« Reply #156 on: June 22, 2011, 07:23:42 AM »
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John,

I did look at the 720 input and output file and, as expected, there is a definite difference in line thickness between the 720 ppi and 360 ppi in column D.  This is true whether the print driver is printing 8-bit, 16-bit, 1440 or 2880 or 2880 with fine detail on or off.  One difference I did note in printing with finest detail off is the 720 ppi rectangle of Column A is a lighter gray to the naked eye than the other ppi rectangles when finest detail is not selected and I cannot make out any hints of vertical lines when viewing under a loupe (I just see darker spots splotched on top of a lighter, seemingly solid background).  With finest detail on, the 240, 360 and 720 rectangles are all darker to the naked eye, and hints of vertical lines may be seen in the 720 rectangle, though not clearly defined.

On the image size front, yes, I could not get the image to the correct DPI within LR when working with US measurements.  In PS, I merely changed the canvas size to 6x4 inches which did nothing to the image's ppi.  In LR, I then set the cell width to 6 inches and all was fine. 
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deanwork
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« Reply #157 on: June 22, 2011, 09:02:49 AM »
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I've used QImage for years on the Hp and it does indeed to an excellent job, especially when upsampling for very large prints from dslr files, as in sending them to the printer at 150 ppi.

I'm wondering if anyone knows exactly what is going on with the Canon IPF plug-in? It seems to be doing something similar for file optimization and also has a slider for output sharpening adjustments that can be changed for various media.

john
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John R Smith
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« Reply #158 on: June 22, 2011, 10:42:20 AM »
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John,

I did look at the 720 input and output file and, as expected, there is a definite difference in line thickness between the 720 ppi and 360 ppi in column D.  This is true whether the print driver is printing 8-bit, 16-bit, 1440 or 2880 or 2880 with fine detail on or off.  One difference I did note in printing with finest detail off is the 720 ppi rectangle of Column A is a lighter gray to the naked eye than the other ppi rectangles when finest detail is not selected and I cannot make out any hints of vertical lines when viewing under a loupe (I just see darker spots splotched on top of a lighter, seemingly solid background).  With finest detail on, the 240, 360 and 720 rectangles are all darker to the naked eye, and hints of vertical lines may be seen in the 720 rectangle, though not clearly defined.

Thank you for the update, Shane. Now what does all this mean? What your results seem to be telling us is that, with the 4900 -

* If you send your printer 720 ppi input, it will process it at 720 no matter what the output quality settings are in the print driver user interface. This mirrors my result with the 2400. (I have a nasty feeling that the opposite is also true, but I have another test to run)

* The “Finest Detail” box does something extra, but it does not select or deselect 720 ppi as has been suggested. It more likely refines the dither pattern in some fashion, hence your observations in block 1, column A. My 2400 when printing 720 ppi with no resampling also prints a block 1 where the lines are just visible with an 8x loupe.

This could change our view of the Epson world, yet again . . .

John
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BartvanderWolf
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« Reply #159 on: June 22, 2011, 11:13:40 AM »
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This could change our view of the Epson world, yet again . . .

That's why I have a bit of a problem with drawing conclusions based on Lightroom output. LR also does it's thing, and doesn't offer enough control to set an exact input PPI, or so it seems. That's fine for regular use (for which it is intended), but not optimal for testing. A test from e.g. Photoshop probably offers more control.

I'd wait a bit for (in)direct feedback from someone like Eric Chan, who also is familiar with Epson printers.

Cheers,
Bart
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