Printing DPI vs Render

[kaelaria]

On my Z3100, I have the options of printing at 600 or 1200 dpi.  I have always rendered my images at 300 dpi at size.  Should I be going to 600 now?

[Sam25]

On my Z3100, I have the options of printing at 600 or 1200 dpi.  I have always rendered my images at 300 dpi at size.  Should I be going to 600 now?
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PPI (pixels per inch) refer to your image file. DPI (dots per inch) refers to your printer’s capability. They are not the same.

I don’t have a Z3100, but I am guessing the difference between the 600 DPI, and 1200 DPI setting is one or two passes of the print head. This is totally unrelated to the image PPI.

Sam

[kaelaria]

Yeah, I'm retarded and realized I confused myself after posting this...forgot to edit/delete!  lol

Sometimes I forget the very basics when I get wrapped up in a project....

Thanks!

[Geoff Wittig]

PPI (pixels per inch) refer to your image file. DPI (dots per inch) refers to your printer’s capability. They are not the same.

I don’t have a Z3100, but I am guessing the difference between the 600 DPI, and 1200 DPI setting is one or two passes of the print head. This is totally unrelated to the image PPI.

Sam
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What Sam said.
You're talking apples & oranges. The native image file resolution accepted by the Z3100 is 300 dpi, meaning any resolution higher than this is thrown away as the printer down-rez's the file.
Printer dpi is a different issue, and this specifies how many passes the printhead makes to paint your image. For what it's worth, I see a noticeable improvement in image quality from my Z3100 when choosing 600 dpi rather than 300, particularly on luster/gloss/satin papers, where the lower resolution occasionally reveals some banding. I've only tried 1200 dpi once or twice, as it causes an absurd increase in printing time, without any visible improvement in image quality. I suspect that on matte/cotton rag papers even 300 dpi would look just fine, but most of the time I'm not in that much of a hurry.
Hope this helps.

[kaelaria]

I just rewatched Camera To Print #12 - even picked up a couple tips regarding the Z3100 specifically I didn't remember.  I've watched it 3 or 4 times already, and still pickup new stuff each time.  Love that series...

[walter.sk]

What Sam said.
You're talking apples & oranges. The native image file resolution accepted by the Z3100 is 300 dpi, meaning any resolution higher than this is thrown away as the printer down-rez's the file.
Printer dpi is a different issue, and this specifies how many passes the printhead makes to paint your image. For what it's worth, I see a noticeable improvement in image quality from my Z3100 when choosing 600 dpi rather than 300, particularly on luster/gloss/satin papers, where the lower resolution occasionally reveals some banding.

I print using Qimage. My files are 300ppi, and the printer resolution is 600dpi with extra passes.  I use this up to 24x36 prints.  I see a difference in smooth transitions over printing at 300dpi, but do not see a difference at 1200dpi.  Maybe the difference would show up in full frame head shots, or in very detailed landscapes, and maybe with much higher  camera resolution than my 1D MkII's 8.1Mp.

[Edhopkins]

What Sam said.
You're talking apples & oranges. The native image file resolution accepted by the Z3100 is 300 dpi, meaning any resolution higher than this is thrown away as the printer down-rez's the file.

Sam

How do you know that 300 dpi is the max that the Z3100 accepts?  I have not seen this in any technical document.  Can you point me to something? I expect I have much to learn.  (We do have a z3100ps GP and do send files to the printer at a resolution of 300 dpi but I was not doing this BECAUSE the printer would throw away and downres anything bigger.)

Thanks for the help!

ed

[kaelaria]

It was mentioned in the C2P series Ep12 21:10 that HP said to send files between 180 and 240, and nothing ever over 480.

[Edhopkins]

It was mentioned in the C2P series Ep12 21:10 that HP said to send files between 180 and 240, and nothing ever over 480.
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? So....

I don't have access to the "Camera 2 print series".  is the second a reference to the Bible?  

I am kind of lost here. I can't tell whether you are jesting or serious.

In any case, what you cite "nothing over 480" is NOT the same as nothing over 300.

This all strikes me as made up. As far as I can tell from the documentation (HP's User guide) the printer will accept 1200 ppi input and produce 1200 dpi output--though I am not sure there is any point in doing this.

The only sentence I could find directly addressing this question in my user manual was the following:

"Print resolution of up to 2400 × 1200 optimized dpi, from a 1200 × 1200 dpi input, using the
Best print-quality option, the Maximum Detail option, and photo paper "

I think they are using "dpi" as equivalent to "ppi" and are referring to the resolution of the image being sent to the printer.

Anyone know this stuff?

ed

[kaelaria]

I'm 100% serious, it was said by Michael - that is the time in the video they are talking about it.  He said he talked to an HP scientist about his Z3100 and they had done extensive testing on this subject already.  If the image is above 150 don't upres.  If you need to upres do so between 180 and 240 dpi.  Also never send a file more than 480 or the print driver will 'choke' as he said.

Get the series, everyone will learn SOMETHING from it.

[rdonson]

Native resolution of the HP Z print driver has been said to be 300 ppi.  

The old conventional wisdom was to uprez to the drivers native capability because the drivers did a lousy job of uprezing.  

This has changed and the current recommendations are as stated by Bryan (Kaelaria).

[Schewe]

I'm 100% serious, it was said by Michael - that is the time in the video they are talking about it.  He said he talked to an HP scientist about his Z3100 and they had done extensive testing on this subject already.  If the image is above 150 don't upres.  If you need to upres do so between 180 and 240 dpi.  Also never send a file more than 480 or the print driver will 'choke' as he said.
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Actually, while he (Mike) was talking about the resolution sweet spot, he said don't resample (merely resize without resampling) if the native resolution of your image is between 180-480PPI.

In the case of Epsons, DON'T uprez beyond 480 because A-it won't buy you anything and B-certain rezes above 480 (particularly around 600) causes potential interference patterens that can actually loose micro-detail.

The key to the resolution issue is try to use the native resolution and let the actual PPI fall where it may as long as the resulting resolution is between 180-480PPI...then sharpen based upon those final resolution settings.

[kaelaria]

Yes, my 2nd post was a typo, I meant 180 as in my first post, not 150.

Transcript:

Michael: "If your file is over 180, let the printer handle it.  Don't upres a file; you know, just because you want to make a bigger print, don't upres the file if it's only 180.  Interesting huh?  He said [HP] if it's under 180, then use Photoshop bicubic, to upres it.  But don't go higher than about 240.  Upres to 180 or 240."

[Ernst Dinkla]

It was mentioned in the C2P series Ep12 21:10 that HP said to send files between 180 and 240, and nothing ever over 480.
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In the past driver up and downsampling was bad if compared to dedicated extrapolation software. Best algorithms available were nearest neighbour etc. It improved to a crude bicubic in drivers later on. Software like Qimage improved as well in that period and can still deliver a better upsampling and downsampling than the driver does.

While the HP driver's extrapolation may have improved to a quality that comes near to what Qimage can do it doesn't have the choice and flexibility in rendering choices and smart sharpening. It is also strange that 180 and 240 PPI  are mentioned as input resolution limits while the Z3100 will ask for 300, 600 and 1200 PPI native resolution depending on media preset and quality settings. A number represented above the preview window of Qimage that it picks up from the Windows API where the driver sets that request. The 180 and 240 PPI mentioned here have that unexplainable relation to the Epson native and print resolutions and not to the HP resolutions. There's no point of discussion that 600 PPI input would be overkill on 99,9 % of the paper qualities but for each paper coating there's a maximum in image quality possible with a given printer and that maximum quality can be translated back to a PPI input number that will be an odd number, not related to the dpi output resolution or PPI native resolution. The driver however defaults to the 3 native resolutions as a kind of stepping stone to create the output patterns with. It is just simpler to create software that way. So that odd 163 PPI or 451 PPI image you load will be upsampled to 300 PPI or 600 PPI or 1200 PPI before it goes into the pattern (dithering, weaving, stochastic screening) generation to make the DPI resolutions. If that driver proves to do better upsampling or downsampling than the software you use for that then there's no reason not to let the driver do that job. Thing is that it has to be checked with the right targets to proof that.

I'm well aware of the qualities of HP engineers but I have some reservations whether the statement above will make Qimage obsolete on its up and downsampling + smart sharpening (there are enough other Qimage features left). Given the difficult cooperation between Qimage and the Z3100 Windows driver I wonder whether there is much experience with that application at HP R&D headquarters. That the Photoshop CS 123 up and downsampling could be surpassed by the Z3100 driver doesn't say much. There's enough extrapolation software including Qimage that can do a better job.

[a href=\"http://www.steves-digicams.com/techcorner/tc_index.html]http://www.steves-digicams.com/techcorner/tc_index.html[/url]

http://www.ddisoftware.com/qimage/quality/


Ernst Dinkla

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

[kaelaria]

Have you done any comparisons on your Z3100, Ernst? I mean printer driver vs. Oimage?

[Ernst Dinkla]

Have you done any comparisons on your Z3100, Ernst? I mean printer driver vs. Oimage?
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Yes, in the past with Epsons and with the Z3100 when I got it. I have done some further testing this morning and it confirms what I have written. I want to check some printing from other applications including Photoshop before I give my verdict.

There's nothing wrong with the HP Z3100 hardware, if it gets the right data it lays down ink on a good coating in an awesome resolution.



Ernst Dinkla

try: [a href=\"http://groups.yahoo.com/group/Wide_Inkjet_Printers/]http://groups.yahoo.com/group/Wide_Inkjet_Printers/[/url]