Printing pixel/inch for best quality

DanE3432 said:

Hi,

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Thanks.

Click to expand...

I send all my files to my Canon printers at 600ppi. There is noticeable improvement in fine detail, compared to 300ppi. I believe Keith Cooper has a video about this on his Northlight Images site.

DanE3432 said:

Hi,

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Thanks.

Click to expand...

Remember not to equate pixels with dots. You need many more dots than pixels. For 720x1440 dpi I doubt anything more than 360 ppi will benefit, especially if upscaled. (Upscaled 360 ppi is not the same as original 360 ppi, as it is difficult to create detail.)

Keith's articles here are good, but recognize that he is comparing various ppi downscaled from 1200 ppi (or 1440 ppi), not various ppi upscaled from a lower ppi original:

https://www.northlight-images.co.uk/best-canon-pro-200-driver-settings/

https://www.northlight-images.co.uk/driver-settings-and-print-detail/

You also need to be a bit of a dot-peeper (next level after pixel-peeper). Keith uses a microscope (mainly to be able to show the differences to others, I would presume.)

wilberforce_1 said:

You also need to be a bit of a dot-peeper (next level after pixel-peeper). Keith uses a microscope (mainly to be able to show the differences to others, I would presume.)

Click to expand...

Absolutely - I draw a huge distinction between 'interesting features' and ones that make visible differences that show ;-)

One of the reasons I looked at downscaling was after I saw some people recommending not printing at a native resolution of say 412 ppi and that resizing to 300 [360] worked better. I wanted to see if increased resolution is indeed fed through to the print (it is)

Upscaling is a whole different question, and one that I will return to when I next get a bigger (24"+) printer to test.

I have some thoughts as to how his will pan out, but the tests linked to earlier were specifically designed to address the question of whether more detail gets through the driver - it does.

My suspicion is that some methods of upscaling may well make for better prints - the question is just what makes a visible difference ;-)

It depends on the image and the type of paper it's going on. The less fine detail that you need/expect, the more you can upscale.

But here's one data point, if it's useful. I have some images with a good amount of fine detail, and I print them on Baryta paper. I upscale using Gigapixel AI, and I feel like the limit is about 2x. So my image that was only a 6x9 at 360 ppi is now a 12x18 at 360 ppi. Then I print with QImage Ultimate, and allow it to upscale further and sharpen. I'm very satisfied with the result. Great detail, much better than without upscaling.

On the other hand, I've got an image that is kind of soft and glowy and it's printed on matte Rag paper. Smooth matte, but still matte. Fine detail is not nearly important, I'm mainly just trying to prevent jaggies and obvious low res artifacts like that.

DanE3432 said:

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Click to expand...

You don't say what type of printer you're using, and 720x1440 dpi sounds pretty low by high-quality modern photo inkjet standards, but probably (because these things are usually integer multiples) that means your printer prints 360 ppi.*

If your printer prints at 360 ppi, and you don't use printing software that automatically resamples to that in a high-quality way (e.g. Qimage), then you will probably get slightly better, and maybe significantly better, results by resampling to 360 ppi in Photoshop.

The old conventional wisdom was that among photo inkjets, Epsons natively print at 360 ppi** and Canons and HPs natively print at 300 ppi. However, many of them also have a mode that lets you double that figure, e.g. to 720 ppi in Epsons and 600 ppi in Canons. In some cases you have to enable that mode with a driver setting (e.g. a "Finest Detail" setting in some Epsons). IME and IMO, going from 300 or 360 ppi to 600 or 720 ppi can sometimes (e.g. depending on the paper and the image) produce a very slight but visible to the naked eye improvement in fine, high-contrast details. What is less clear to me is whether there is a corresponding reduction in tonal smoothness and/or color accuracy. Imagine your printer: at 360 ppi you'd have a 2x4 = 8 space grid of addressable locations at which the printer can spray droplets of its however-many (between 3 and 11) colors of ink (or not); at 720 ppi you'd only have a 1x2 = 2 space grid. I don't care how many colors of ink you have, you can't simulate continuous tone (i.e. hundreds of thousands of visibly-distinct colors) with only two spaces at which to drop the at most 11 colors of ink.

Qimage does an excellent job sorting all this out for you 'under the hood' and with minimal intervention from you. Lightroom can do a very good job (but with Lightroom you have to know what ppi value to set). I don't doubt that other software can do it well.

*For more on that, see, e.g., https://www.dpreview.com/forums/post/60327729 .

**Some but not all newer Epsons natively print at 300 ppi, e.g. the P7570, P9570, P10000, and P20000.

DanE3432 said:

Hi,

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Thanks.

Click to expand...

Epson printers typically have a native print resolution of 360PPI or 720PPI depending on the print quality setting in your printer driver. Canon, HP and most other inkjets have a native print resolution of 300PPI or 600PPI

Basically, whatever the image's PPI setting is for the paper size, the printer will resample the image to its native print resolution before outputting the print.

This is a description of actually happens "under the hood" when you submit an image to an inkjet printer.

First I need to clear up the difference between PPI (Pixels Per Inch) and DPI (Dots of ink Per Inch). PPI should be straight forward for everyone. DPI is the print quality setting you set in the printer driver. Normally I set the print quality on my Epson P600 to 1440 DPI x 1440 DPI as shown below.



So, what happens when you send a digital image to a printer?

For the sake of simplicity I will be using a 2470px x 1976px (5:4 aspect) image and describe what I would do in my Photoshop Elements.

The first thing I need to do is size the image, without resampling, to the paper size I want to print to as shown below.



I enter the values 10in x 8in and PSE automatically calculates that the PPI for that paper size is 247 PPI. Had I entered a paper size of say 12in x 9.6in (still 5:4) PSE would have calculated a resolution of 205.8 PPI for the paper size.

But how does the printer know to print that 2470px x 1976px image to 10in x 8in or 12in x 9.6in because the printer does not know the paper dimensions I entered in PSE?

This is where I believe the printer's native print resolution comes into play.

Let's say I want a 10in x 8in print. The 247 PPI value for that paper size is made known to the printer somewhere in the print pipeline, where exactly is irrelevant.

Now, the printer wants image files at the printer's native print resolution, 360 PPI in this case. The image's PPI for the 10in x 8in paper size is only 247 PPI so the printer driver resamples the 2470px x 1976px image to 360PPI for the paper size by the math -

360/247 x 2470 = 3600px wide

360/247 x 1976 = 2880px high

The printer then reads the rgb data from the resampled 3600px x 2880px image in lots of 360 pixels at a time and converts it to data that shows how much of each of the printer's ink colours are to be laid down in 1440 dots of ink.

The printer then prints those 1440 dots of ink over 1 inch of paper at a time resulting in a 10in x 8in print.

NAwlins Contrarian said:

NAwlins Contrarian said:

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Click to expand...

You don't say what type of printer you're using, and 720x1440 dpi sounds pretty low by high-quality modern photo inkjet standards, but probably (because these things are usually integer multiples) that means your printer prints 360 ppi.*

If your printer prints at 360 ppi, and you don't use printing software that automatically resamples to that in a high-quality way (e.g. Qimage), then you will probably get slightly better, and maybe significantly better, results by resampling to 360 ppi in Photoshop.

The old conventional wisdom was that among photo inkjets, Epsons natively print at 360 ppi** and Canons and HPs natively print at 300 ppi. However, many of them also have a mode that lets you double that figure, e.g. to 720 ppi in Epsons and 600 ppi in Canons. In some cases you have to enable that mode with a driver setting (e.g. a "Finest Detail" setting in some Epsons). IME and IMO, going from 300 or 360 ppi to 600 or 720 ppi can sometimes (e.g. depending on the paper and the image) produce a very slight but visible to the naked eye improvement in fine, high-contrast details. What is less clear to me is whether there is a corresponding reduction in tonal smoothness and/or color accuracy. Imagine your printer: at 360 ppi you'd have a 2x4 = 8 space grid of addressable locations at which the printer can spray droplets of its however-many (between 3 and 11) colors of ink (or not); at 720 ppi you'd only have a 1x2 = 2 space grid. I don't care how many colors of ink you have, you can't simulate continuous tone (i.e. hundreds of thousands of visibly-distinct colors) with only two spaces at which to drop the at most 11 colors of ink.

Click to expand...

I recall having heard about adjustments of drop sizes which may be part of the differences between 300 vs 600, and 360 vs 720 modes. Maybe the color resolution question you raised is moot?

I’m very curious about the dithering that goes on when creating pixels out of mere dots, and have on order a device that lets my phone act as a microscope to let me poke around a bit on that.

NAwlins Contrarian said:

Qimage does an excellent job sorting all this out for you 'under the hood' and with minimal intervention from you. Lightroom can do a very good job (but with Lightroom you have to know what ppi value to set). I don't doubt that other software can do it well.

Click to expand...

My experience with printing from Lightroom to my Epson printer is that the 720 mode brings so very little more than 360 that I just stick with 360 and never worry. On the other hand printing from Qimage vs LR is a more significant difference and worth doing sometimes. However I do waste more paper and ink in the process of correcting my careless user mistakes in Qimage due to it’s less intuitive user interface.

--
Wag more; bark less.

just Tony said:

just Tony said:

What is less clear to me is whether there is a corresponding reduction in tonal smoothness and/or color accuracy. Imagine your printer: at 360 ppi you'd have a 2x4 = 8 space grid of addressable locations at which the printer can spray droplets of its however-many (between 3 and 11) colors of ink (or not); at 720 ppi you'd only have a 1x2 = 2 space grid. I don't care how many colors of ink you have, you can't simulate continuous tone (i.e. hundreds of thousands of visibly-distinct colors) with only two spaces at which to drop the at most 11 colors of ink.

Click to expand...

I recall having heard about adjustments of drop sizes which may be part of the differences between 300 vs 600, and 360 vs 720 modes. Maybe the color resolution question you raised is moot?

I’m very curious about the dithering that goes on when creating pixels out of mere dots, and have on order a device that lets my phone act as a microscope to let me poke around a bit on that.

Click to expand...

It's my distinct impression--but I'm far from certain about this--that with one exception (more on that below), printers that can print more than one size of ink droplet (typically rated in picoliters) nevertheless use only one size of droplet in any given print, and what changes the droplet size is the quality setting. So e.g. if you print at 5760x1440 dpi the printer prints only / all 1.5 pl droplets, but if you print at 1440x1440 dpi, then the printer prints only / all 5 pl droplets, or something like that. What I don't know is whether e.g. printing at 5760x1440 dpi and printing at 720 ppi are separately-selectable; or e.g. setting the driver for either 5760x1440 dpi or 720 ppi always means you also get the other, and setting the driver for 2880x1440 dpi or 360 ppi always means you get the other.

The exception of which I'm aware are certain HP printers with its "dual drop technology", which HP touts as providing equal image quality without the need for light-colored inks. Even in the current flagship photo printer, the Z9+, all this means is that some (but not all) ink colors can spray two different drop sizes on the same print. Specifically, the Z9+ can spray 7 pl and/or 3 pl droplets of cyan, magenta, photo black, gray, or blue ink, but only 6 pl droplets of yellow, matte black, red, or green ink; by doing so it apparently doesn't need light cyan, light magenta, or light gray ink. See the datasheet at https://h20195.www2.hp.com/v2/GetDocument.aspx?docname=c07914104, as accessed from https://www.hp.com/us-en/printers/large-format/designjet-z9-series-printer.html.

On my Epson P600, the paper type also plays a part in the native printer resolution the printer asks for (360 PPI or 720 PPI) in addition to the print quality setting in DPI I set in the printer driver.

For example, if I set 1440 DPI x 1440 DPI print quality and glossy photo paper then the printer reports back to the Photoshop Elements print dialogue box that it wants the image at 720 PPI.

But if I select a much lower quality paper type, like plain photocopy paper, and stay with 1440 DPI x 1440 DPI print quality then the printer asks for a 360 PPI image.

NAwlins Contrarian said:

NAwlins Contrarian said:

I’m very curious about the dithering that goes on when creating pixels out of mere dots, and have on order a device that lets my phone act as a microscope to let me poke around a bit on that.

Click to expand...

It's my distinct impression--but I'm far from certain about this--that with one exception (more on that below), printers that can print more than one size of ink droplet (typically rated in picoliters) nevertheless use only one size of droplet in any given print, and what changes the droplet size is the quality setting. So e.g. if you print at 5760x1440 dpi the printer prints only / all 1.5 pl droplets, but if you print at 1440x1440 dpi, then the printer prints only / all 5 pl droplets, or something like that. What I don't know is whether e.g. printing at 5760x1440 dpi and printing at 720 ppi are separately-selectable; or e.g. setting the driver for either 5760x1440 dpi or 720 ppi always means you also get the other, and setting the driver for 2880x1440 dpi or 360 ppi always means you get the other.

The exception of which I'm aware are certain HP printers with its "dual drop technology", https://h20195.www2.hp.com/v2/GetDocument.aspx?docname=c07914104, as accessed from https://www.hp.com/us-en/printers/large-format/designjet-z9-series-printer.html.

Click to expand...

Another factor could be the difference between Epson's piezo cold firing printhead and ie. Canon's thermal printhead.

Canon's Pro 10 :

40X



Epson's R800

40X



The above may not be the best to show differences but the Canon seems to be quite uniform dot size and the Epson seems to show variation in dot sizes. Things may show differences if I select a highest quality vs lowest quality setting. ( I only have the Canon now -R800 is long gone)

A good explanation of ppi and dpi is given here:

https://castleink.com/blogs/printer-help/inkjet-printer-resolution-dpi-printer-guide

Another discussion on this has some details on how a printer lays down dots. Do they vary in size or placement?

Keith Cooper said:

wilberforce_1 said:

You also need to be a bit of a dot-peeper (next level after pixel-peeper). Keith uses a microscope (mainly to be able to show the differences to others, I would presume.)

Click to expand...

Absolutely - I draw a huge distinction between 'interesting features' and ones that make visible differences that show ;-)

One of the reasons I looked at downscaling was after I saw some people recommending not printing at a native resolution of say 412 ppi and that resizing to 300 [360] worked better. I wanted to see if increased resolution is indeed fed through to the print (it is)

Upscaling is a whole different question, and one that I will return to when I next get a bigger (24"+) printer to test.

I have some thoughts as to how his will pan out, but the tests linked to earlier were specifically designed to address the question of whether more detail gets through the driver - it does.

My suspicion is that some methods of upscaling may well make for better prints - the question is just what makes a visible difference ;-)

Click to expand...

Looking forward to your test results, when available.

dRomano said:

I upscale using Gigapixel AI, and I feel like the limit is about 2x. So my image that was only a 6x9 at 360 ppi is now a 12x18 at 360 ppi.

Click to expand...

That's 4x

Euell said:

dRomano said:

I upscale using Gigapixel AI, and I feel like the limit is about 2x. So my image that was only a 6x9 at 360 ppi is now a 12x18 at 360 ppi.

Click to expand...

That's 4x

Click to expand...

It's 4 times the image area but a 2x enlargement because it's enlarged in both dimensions

As to the issues N'Awlins mentions, I'm guessing that the author of QImage has thought through that for us.

Lot of ways to skin a ... and I wouldn't underestimate the imaging engineers at Canon, Epson, HP. I don't printer larger than 12 x 18 inches, so I never bother with trying to hit those supposedly magic numbers.

NAwlins Contrarian said:

It's my distinct impression--but I'm far from certain about this--that with one exception (more on that below), printers that can print more than one size of ink droplet (typically rated in picoliters) nevertheless use only one size of droplet in any given print, and what changes the droplet size is the quality setting. So e.g. if you print at 5760x1440 dpi the printer prints only / all 1.5 pl droplets, but if you print at 1440x1440 dpi, then the printer prints only / all 5 pl droplets, or something like that.

Click to expand...

Hi NA, during my time in printer development more than one size could be printed during the print to enable variable dot/multiple intensity printing. That is simplifying a huge subject including the potential differences between the vari-dot asked for by a printer driver in the printer language and what the print marking mechanisms (head, head placement etc) produce.

The readability varies but you can find some practical information if you are interested in patents from the obvious supects such as Canon, Epson and HP. If you search on terms like "variable dot inkjet" or "multiple intensity inkjet" in patent searches you will find some info. I didn't read into them closely but two random examples:


It's not a hard rule but turning to your resolution examples, extreme resolution can often suggest a single intensity dot, whilst a mid-resolution suggests a variable dot. Interestingly in the single intensity dot the driver dev has a choice, either print with the single intensity at that high resolution, or use some of the resolution to create a multiple intensity "variable dot" in s/w.

NAwlins Contrarian said:

What I don't know is whether e.g. printing at 5760x1440 dpi and printing at 720 ppi are separately-selectable; or e.g. setting the driver for either 5760x1440 dpi or 720 ppi always means you also get the other, and setting the driver for 2880x1440 dpi or 360 ppi always means you get the other.

Click to expand...

Where are you selecting 720 ppi in your driver?

Keith Cooper said:

One of the reasons I looked at downscaling was after I saw some people recommending not printing at a native resolution of say 412 ppi and that resizing to 300 [360] worked better. I wanted to see if increased resolution is indeed fed through to the print (it is)

[snip]

I have some thoughts as to how his will pan out, but the tests linked to earlier were specifically designed to address the question of whether more detail gets through the driver - it does.

Click to expand...

Nothing wrong with black box testing and it has the nice aspect that ultimately print quality is about what ends up on the page, but be aware your results will be application dependent. The app decides what scaling is asked of the printer driver.

DanE3432 said:

When upscaling an image in Photoshop what is the best pixel/inch to go for 300, 360, 720 etc? I have carefully checked all upscaled images and they look good without any artefacts but I am not sure if more is better or if at some point the more pixel/inch will result in a more blurry print. My printer’s best quality mode is 720x1440dpi – any help on what I should do to get the best result would be appreciated.

Click to expand...

300 vs 360 relates to the design of the print head and its pitch. Traditionally 300 for Canon and HP, 360 for Epson.

I am a great believer in figuring out your own needs so if you see no improvement go with whatever you feel happy with. The printer and app will both be limiting factors.

The app decides what gets fed to the printer driver. So if you keep going with ever higher resolutions it may not result in a blurry print, but the app simply downsampling before passing the image. The printer driver and app talk to each in both physical and logical measurements. So if in the app you say print into this 6x5 box then either the app or printer driver will scale to make it fix. The app decides which it is.

Although obviously related the input app image and the output print data live in different image processing realms. The input is continuous tone, the output side takes each picture element in the input and uses a collection of tools to trick your visual system into thinking the print is also continuous tone. So in the general sense although it is logical to see a connection between say 720 dpi on input and your 720x1440dpi print quality in practise it is not as simple.

Unless your chasing down diminishing returns for most people try 300/600 or 360/720 input depending on your printer mgfr as input with your preferred output settings see what looks good and enjoy your photography/printing. Other things in the print process will make a bigger difference.

For example, if I set 1440 DPI x 1440 DPI print quality and glossy photo paper then the printer reports back to the Photoshop Elements print dialogue box that it wants the image at 720 PPI.

But if I select a much lower quality paper type, like plain photocopy paper, and stay with 1440 DPI x 1440 DPI print quality then the printer asks for a 360 PPI image.

Where are you seeing this? Thanks.

As I posted earlier, in my printer driver and on my Photoshop Elements print dialogue box.