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Print dpi

  
 
Zenon Char
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p.2 #1 · p.2 #1 · Print dpi


I forgot about this. If you look at LrC's Web module it does not even offer PPI. Only quality and sharpening.      



Nov 27, 2022 at 01:22 PM
story_teller
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p.2 #2 · p.2 #2 · Print dpi


mcbroomf wrote:
PPI is used for both display and printing. When printing it will tell you the size print you can make for a given print PPI and pixel dimension. eg a 3600 pixel wide file printed at 360 PPI will give you a 10" wide print. Very important for us printers.


That's only because the terms have been misused over the years by people who didn't know the difference. A pixel is a screen term. A dot is a term for a printer. They are now interchangeable because the misuse over the years, not because they are technically correct.

This is from the Merriam-Webster dictionary -

pixels
1
: any of the small discrete elements that together constitute an image (as on a television or digital screen)
If the ball is flying from left to right across a video screen, a pixel at one fixed location on the screen will get darker and darker as time ticks on because it depicts points farther and farther to the left on the ball.
Frédo Durand et al.

Other common mis-uses -
Hard drive vs SSD
Disk vs Disc
Affect vs Effect
Referring to a simple video interface as a GPU
etc.



Nov 28, 2022 at 07:43 AM
Zenon Char
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p.2 #3 · p.2 #3 · Print dpi


Explains why Canon has used DPI forever. On an other note. One file was exported at 1 PPI. The other at 5,000 PPI. Which is which?












Nov 28, 2022 at 11:20 AM
Peter Figen
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p.2 #4 · p.2 #4 · Print dpi


Zenon Char wrote:
Explains why Canon has used DPI forever. On an other note. One file was exported at 1 PPI. The other at 5,000 PPI. Which is which?


It doesn't matter because all a browser is going to do is display the number of pixels in the file.



Nov 28, 2022 at 11:58 AM
mcbroomf
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p.2 #5 · p.2 #5 · Print dpi


story_teller wrote:
That's only because the terms have been misused over the years by people who didn't know the difference. A pixel is a screen term. A dot is a term for a printer. They are now interchangeable because the misuse over the years, not because they are technically correct.
....


Yes, totally different. For printing on lustre paper I typically print at 360 PPI with 720 x 1440 DPI



Nov 28, 2022 at 02:05 PM
story_teller
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p.2 #6 · p.2 #6 · Print dpi


Just because something has been used and accepted for a while doesn't make it correct. Feel free to use it incorrectly, The Print Industry Glossary of Printing and Graphic Terms" doesn't recognize the term pixel or PPI, but it does recognize the term DPI.

https://www.printindustry.com/Glossary.aspx



Nov 29, 2022 at 06:35 AM
Zenon Char
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p.2 #7 · p.2 #7 · Print dpi


story_teller wrote:
Just because something has been used and accepted for a while doesn't make it correct. Feel free to use it incorrectly, The Print Industry Glossary of Printing and Graphic Terms" doesn't recognize the term pixel or PPI, but it does recognize the term DPI.

https://www.printindustry.com/Glossary.aspx


Depends in what what you are using to print at the commercial or non commercial level.

https://www.myprintsouth.com/resources/blog_articles.html/article/2018/06/07/what-you-should-know-about-lpi-dpi-and-ppi

http://resources.printhandbook.com/pages/dpi-for-printing.php

I never worked in pre press. I know they did 4 colour separations using PS but really didn't know how they output to achieve the correct LPI for the offset presses. I thought there might be a separate page for this but apparently not.

https://helpx.adobe.com/ca/photoshop/using/printing-images-commercial-printing-press.html



Nov 29, 2022 at 09:54 AM
John Wheeler
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p.2 #8 · p.2 #8 · Print dpi


Cambridge in Color has been a long term great site on a number of image (camera and printing) information. Here is the link about PPI which also covers DPI and the difference:
https://www.cambridgeincolour.com/tutorials/digital-camera-pixel.htm



Nov 29, 2022 at 01:55 PM
dclark
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p.2 #9 · p.2 #9 · Print dpi


story_teller wrote:
Just because something has been used and accepted for a while doesn't make it correct. Feel free to use it incorrectly, The Print Industry Glossary of Printing and Graphic Terms" doesn't recognize the term pixel or PPI, but it does recognize the term DPI.

https://www.printindustry.com/Glossary.aspx


But they got it wrong!!



Nov 29, 2022 at 11:23 PM
RustyBug
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p.2 #10 · p.2 #10 · Print dpi


mcbroomf wrote:
Yes, totally different. For printing on lustre paper I typically print at 360 PPI with 720 x 1440 DPI


Which ... (question) would effectively be printing two drops of ink per pixel and four drops of ink per pixel (respective direction).

Whereas if printing at 180 Pixel / Inch and 720 Dots / Inch x 1440 Dots / Inch ... the ratio is now four to one and and eight to one ... making for a larger (printed) pixel (offset by different viewing distances for visual perception of "sharp" or "soft").

Am I getting that right?



Nov 30, 2022 at 06:03 AM
 


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mcbroomf
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p.2 #11 · p.2 #11 · Print dpi


Well you get the same dot dithering per inch, but more per pixel as you say (at 180PPI). However you are submitting a file with less actual resolution at 180 PPI than 360 PPI and testing has shown that it can be seen (in fact some paper peepers (ie not screen pixel peepers) maintain that a file can benefit being printed at 720 PPI over 360 under the right circumstances. I know that canvas printers often don't go any higher than 180 to 240 (perhaps others with more experience can chime in, I print canvas but using the same files as I print papers, so I have plenty of pixels). And as you say viewing distance matters.

I gave up paper peeping a long time ago, maybe once sensors got to or over the 36MP mark. I uprez from 240 to 360 at a given print size if needed but don't go further. If I happen to have more than 360PPI to start with I just leave it.

In other word, yes and I think we agree ....



Nov 30, 2022 at 07:02 AM
story_teller
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p.2 #12 · p.2 #12 · Print dpi


Ok, I see what you are saying, but PPI still refers to Pixels Per Inch. According to the Adobe document listed above, to print a reasonable representation of an image displayed on a monitor (in PPI), you need to determine a DPI setting for a specific printer. PPI is being used as a guide to set print quality. In other words, you need a certain DPI (printer dependent) to match a corresponding PPI line scan rate being displayed. The terms still don't mean the same thing and are not interchangeable.


Dec 01, 2022 at 07:26 AM
gunmetal
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p.2 #13 · p.2 #13 · Print dpi


mcbroomf wrote:
Well you get the same dot dithering per inch, but more per pixel as you say (at 180PPI). However you are submitting a file with less actual resolution at 180 PPI than 360 PPI and testing has shown that it can be seen (in fact some paper peepers (ie not screen pixel peepers) maintain that a file can benefit being printed at 720 PPI over 360 under the right circumstances. I know that canvas printers often don't go any higher than 180 to 240 (perhaps others with more experience can chime in, I print canvas but using the same files
...Show more

I would be curious to see the tests that show a visible difference in 720 PPI vs 360. I struggle to see the difference in 320 vs 240 in an A3 print from 2' away from a 20MP sensor. Then again, I hit 45 years old and my vision up close went to crap,



Dec 02, 2022 at 11:03 AM
chez
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p.2 #14 · p.2 #14 · Print dpi


gunmetal wrote:
I would be curious to see the tests that show a visible difference in 720 PPI vs 360. I struggle to see the difference in 320 vs 240 in an A3 print from 2' away from a 20MP sensor. Then again, I hit 45 years old and my vision up close went to crap,


Given we all seem to pixel peep at 100% or more when evaluating sharpness of lenses, why would we not evaluate prints with a magnifying glass?



Dec 02, 2022 at 11:21 AM
mcbroomf
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p.2 #15 · p.2 #15 · Print dpi


Yea ... I think unless you do them yourself they mean nothing. By that I mean you can't take a photo of a 360 vs 720 PPI print and expect anyone to see on screen (from a miserable jpg + internet) the difference.

I can't recall where I read it, probably on Luminous Landscape and maybe decade(s) ago by either Michael or maybe Jeff Schewe. I'd say if you can't see it (I can't) don't worry. I print at 360 if I can but either down to 240 or interpolate up from there (to 360). I think it was also Jeff Schewe who said a good bottom limit to go for was 180 dpi, IOW below that and you will see a clear difference. Bear in mind that this would have been said with interpolation and printer tech of that age and may be much better now (so easier to see if our eyes can).

I do like to print large so today's much higher MP sensors make it easier to keep in that range.

I know what mean about eyes but dual cataract surgery gave mine a new life ...



Dec 02, 2022 at 11:31 AM
ilkka_nissila
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p.2 #16 · p.2 #16 · Print dpi


gunmetal wrote:
I would be curious to see the tests that show a visible difference in 720 PPI vs 360. I struggle to see the difference in 320 vs 240 in an A3 print from 2' away from a 20MP sensor. Then again, I hit 45 years old and my vision up close went to crap,


Right, but if you use glossy paper and make relatively small prints, and observe them with 20-year-old eyes, subtle differences can be visible. I remember seeing subtle differences when I was younger but nowadays I just print at 360 ppi. I don't use glossy paper on my pigment inkjet because viewing angle affected the image too much. With semiglossy, luster or matte paper, I am not sure if it makes any difference if I go higher than 360 ppi. I am happy with the appearance of the prints and since I nowadays have the option of printing quite large, I am not as concerned with the sharpness of small prints (that I do for various purposes such as evaluating how a set of images work together and optimizing the visual story). I can just print larger if I want to see more detail.

As long as I have been making prints, the term pixels per inch was used to quantify how many pixel rows or columns in the digital image (this has nothing to do with the display I use) are supplied to the printer driver. The driver then uses the manufacturer's preferred algorithms to control the printer to place droplets of ink on the paper. The printers typically have 720 x 2880 dpi specs but as a user I don't need to know how exactly the printer uses its hardware to achieve the final image. Out of habit I send the file resampled to 360 ppi to the driver because it is one half of the dpi value on one axis, but this was just a recommendation (to use either 360 or 720 on these devices) but I haven't rigoroslytested if it makes any difference if I send the file at its native resolution. Sometimes I do just that and let the printer driver sort it out. The outcome appears the same as far as I can tell. Maybe some more picky eyes can discern these subtle differences. For my purposes the printer driver takes low level control of the printer so that I don't need to.



Dec 02, 2022 at 11:38 AM
gunmetal
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p.2 #17 · p.2 #17 · Print dpi


chez wrote:
Given we all seem to pixel peep at 100% or more when evaluating sharpness of lenses, why would we not evaluate prints with a magnifying glass?


It's a good question. One that I've never really given any thought to likely because I don't have to have an additional tool when pixel peeping on a computer. Serious question here: Do individuals who go to art galleries/exhibits bring a magnifying glass with them?



Dec 02, 2022 at 03:41 PM
chez
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p.2 #18 · p.2 #18 · Print dpi


gunmetal wrote:
It's a good question. One that I've never really given any thought to likely because I don't have to have an additional tool when pixel peeping on a computer. Serious question here: Do individuals who go to art galleries/exhibits bring a magnifying glass with them?


I highly doubt it. Do people that view prints at a gallery want to zoom in 100% into the image that created the print. I just find it interesting that we obsess over the quality of images created by a lens, taking images of brick walls and viewing them at 100 or even 200% just to get that one lens that is just so great…and then when the rubber hits the road in a print…well things are just good enough.





Dec 02, 2022 at 05:53 PM
amv8
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p.2 #19 · p.2 #19 · Print dpi


gunmetal wrote:
I would be curious to see the tests that show a visible difference in 720 PPI vs 360. I struggle to see the difference in 320 vs 240 in an A3 print from 2' away from a 20MP sensor. Then again, I hit 45 years old and my vision up close went to crap,


I've specifically tested the following cases using my Canon Pro 1000 printer (note the Canon takes either 300 dpi or 600 dpi as native resolutions).

- input file size is 300 dpi and printed at 300 dpi using QImage One
- input file size is 300 dpi and printed at 600 dpi using QImage One and QImage One's upscaling to 600 dpi
- input file size is 600 dpi and printed at 600 dpi

In all cases, I used just a slight amount of QImage One's proprietary "Depth Focus Sharpening." Upscaling the dpi to 600 dpi improved the print quality over the original 300 dpi prints, and providing a 600 dpi input file improved a tiny bit more. I wouldn't notice the differences from a two or three feet or more away (they were 4"x6" test prints), but upon closer viewing yes. I didn't expect to see these improvements. Now, when I'm making a final print, I either upscaling to 600 dpi or providing a 600 dpi file as input.



Dec 02, 2022 at 06:13 PM
Peter Figen
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p.2 #20 · p.2 #20 · Print dpi


gunmetal wrote:
It's a good question. One that I've never really given any thought to likely because I don't have to have an additional tool when pixel peeping on a computer. Serious question here: Do individuals who go to art galleries/exhibits bring a magnifying glass with them?


No, but they do walk right up to prints with reading glasses on. Some like to see the up close micro detail and others like to stand back and take it all in. I remember when Mountain Light was still open that when you walked right up to one of the 32x48 prints from Kodachrome that were displayed there, there was obvious, and to me, objectionable, stair stepping in the print. Reason: Not enough resolution in the drum scanner they used. At a certain point, those types of artifacts do become a problem on a subconscious level for the critical viewer, and it's even worse when it's not in your subconscious anymore.




Dec 02, 2022 at 06:45 PM
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