[TonyW]

In a recent Medium Format thread the subject of printing cropped up including a discussion of what to send to the printer and does it really matter. While the topic started around MF or Canon 5D for high resolution printing it is just as relevant to FF and crop sensor image printing so thought this may be of interest to others in the Printing section of the forum for those that may not visit the MF. The original thread HERE

I hope that this may be of interest and that I am not seen as trying to teach granny to suck eggs

One of the subjects was related to how many ppi needed for a good print resolving the maximum information contained in the capture data. While there is a lot more to making a good print the ability to resolve the finest detail contained within your captured data must surely rank quite highly? So in this case we are talking about what PPI the printer needs to make the most of our image data.

I believe that in the case of Epson the driver reports to the OS that it expects image input of either 360 or 720 ppi, Canon would expect 300 or 600 ppi. For output to the print paper then the DPI (droplets per inch) will be controlled by the driver based on paper type and quality selected and is likely to be several times that of the image ppi.

Anyway the discussion did get me thinking and wondering how good my cheapo Canon MP495 everyday inkjet would cope. This printer must be among the cheapest you can buy at £45 ($58). It uses two cartridges, one black and one containing CYM, the cost of the two at retail prices nearly equal to the cost of the printer!

The result for such a cheap printer took me by surprise.

There are many test that you could undertake for assessing print quality, I decided to limit this to two one being a resolution test based on fine lines (from Mike Chaney Qimage and shown in MF post linked above) and sending the printer data at 600 ppi and 150 ppi and a composite of sections of a real raw image from a Pentax K1 from DPR at 600 and 100 ppi (meant to send 150 but...).

Both files had enough pixels at native resolution to print images @ 600 ppi that fitted well within A4 paper borders. It should be noted that with larger image requirements you will run out of pixels from the native file resolution and of course you will have to upscale via your editing app PS or LR or allow the print driver to do this. The general consensus is that you should let Adobe handle it as the processing algorithms should do a better job than leaving it to the printer driver.

Not having any best quality A4 paper these were printed on Canon Satin a semi gloss paper at best quality setting. To show the actual print I needed to scan the images and used an Epson V500 @ 600 SPI. To enable the differences to be viewed clearly on the web I cropped and zoomed the images.

You will just have to trust me when I tell you that the differences you see correspond to what I saw and describe on the A4 prints or of course even better grab some images yourself and print .

This is a section of an image when printed is sized at 6.7" x 4.4 (marked the print with 2" line to give idea of the zoom). As can be seen the left side of the image is from a print @ 150 ppi and the right hand side printed at 600 ppi. I do not have 20/20 vision and need to wear reading glasses but what I can tell you is viewing the print at 10-12" reveals the detail improvement you see here pretty precisely.


This is the DPR composite from the K1, just using the 100ppi and 600 ppi versions. For this I just made a screen grab of both images within PS. Once again the gain in IQ seen on the right is what I see on the printed version viewing at the same distance as the first image. The print area in this case 7.5" x 4.5"


The surprise for me is that the little cheapo printer really handled these images very nicely indeed at least IMHO

---

Last edited by TonyW; 08-31-2016 at 11:52 AM. Reason: Correct Canon ppi to 600

[Alex645]

Tony,
This is very interesting. I was always told the holy grail for printing was 300 ppi/dpi for color and 240 ppi/dpi for monochrome. It is not clear to me if this limitation is based on offset screen dot patterns or inkjet paper absorbency, but if we are just talking about inkjet printing, I would love to see an additional comparison in your test at 300.

I should also add I'm a bit confused over the labels "printed @ 600 ppi". You meant the print came from a 600 resolution image? Normally I print 300 res images at 1440 dpi settings on an Epson inkjet printer. When I've tried 2880 dpi, I've never found a paper that could handle that detail and ink.

[Adam]

Ultimately it depends on how closely you'll be examining your prints, and what resolution your camera shoots at. If your files are big enough, there's no reason not to print at max DPI if you want to prioritize quality.

[mohb]

Most people will be happy with what their printer decides is 'high quality,' those who want to argue the toss about ppi/dpi or whatever never seem to define the relevance of their exalted standards to those of us who hang our photos on the wall

[normhead]

Awesome stuff, TonyW.... I've spend a lot of time searching for this kind so stuff and, honestly to date, it's the best I've seen.

[TonyW]

Hi Alex, thanks for your interest to try and address your points at least based on my current understanding

I was always told the holy grail for printing was 300 ppi/dpi for color and 240 ppi/dpi for monochrome. It is not clear to me if this limitation is based on offset screen dot patterns or inkjet paper absorbency, but if we are just talking about inkjet printing, I would love to see an additional comparison in your test at 300.

My view is that 300 ppi is one of those myths that has permeated the net in particular, although probably has some basis in fact - I suspect that you are correct and and that this comes from the requirements for screen image and dot patterns.

A rough guide says if you are to print for a magazine at 150 LPI then 300 PPI equates to the same. What is really bad to hear IMO is that no one can see any image improvements over 300 ppi as that is the limit of human visual acuity. Clearly not the case as far as inkjet printing goes.

It is also irrelevant for many inkjet printers as some require 360 or 720 ppi i.e. Epson and ? whereas Canon and HP requirements are 300 and 600

I should also add I'm a bit confused over the labels "printed @ 600 ppi". You meant the print came from a 600 resolution image? Normally I print 300 res images at 1440 dpi settings on an Epson inkjet printer. When I've tried 2880 dpi, I've never found a paper that could handle that detail and ink.

Yes I could have made it clearer printed from the image at 600 ppi.

Just to be clear your camera capture does not have any size other than the number of pixels in the x and y directions i.e. native size. It only has a size when you declare such by picking the ppi you require for instance to print 150, 200, 240, 300, 360, 600 or 720 ppi - you can also pick the finished print size and the ppi (which may involve upsample/downsample).

To guarantee that you are getting the best from your data if the finished size does not come to your printers native ppi then you should probably upsample in your editor of choice rather than allow the printer driver to do this - remembering your printers requirements, in your case with Epson 360 or 720.

So really in your case with a finely detailed image there may be benefits to using 360 or 720 ppi. Your 1440 dpi printer setting is squirting up to 4 droplets of ink per pixel when you send it 360 ppi and 2 when you send it 720 ppi - in truth it is not quite that simple as inks will be overlaid but maybe a good way to think about it.

---------- Post added 08-30-16 at 12:02 PM ----------

Ultimately it depends on how closely you'll be examining your prints, and what resolution your camera shoots at. If your files are big enough, there's no reason not to print at max DPI if you want to prioritize quality.

You are spot on about distance viewing and in the other post I offered some ways to calculate what ppi required.

However it should also be born in mind that while you may have to accept that to get your print size from your native file size you will have to resample that it is not always ideal to just let the system get on with it as up to date printer processing algorithms inherent in the drivers do not seem to give as good a result as those from Adobe and perhaps LR in particular. There are other applications for printing that may be even better e.g. Qimage.

The bottom line seems to be if you have an image that has only 100 ppi to make a print of the required size then it will have to be upscaled somehow and you probably do not want to allow the OS or the printer driver to handle it when there are better options available

---------- Post added 08-30-16 at 12:04 PM ----------

Most people will be happy with what their printer decides is 'high quality,' those who want to argue the toss about ppi/dpi or whatever never seem to define the relevance of their exalted standards to those of us who hang our photos on the wall

OH dear seems to me someone has got out of the wrong side of the car today If you cannot see the relevance of what is posted fine - perhaps glasses are in order

---------- Post added 08-30-16 at 12:05 PM ----------

Awesome stuff, TonyW.... I've spend a lot of time searching for this kind so stuff and, honestly to date, it's the best I've seen.

Thanks norm, I know that you were not over the moon with the initial results from your Canon printer. I really believe that it should be able to knock your socks off.

[normhead]

Thanks norm, I know that you were not over the moon with the initial results from your Canon printer. I really believe that it should be able to knock your socks off.

I'm sure it would TonyW, my problem is I'd rather be shooting, and because my printing sessions are often 6 months apart, dry ink, forgetting how i got the results I got last time were achieved, and the fact that i rarely even tried to print unless I had a show deadline coming up, meant I really wasn't developing any proficiency. I'm sure a lot are in the same boat.

Don't get me wrong, I did gets some amazing results, but, not reliably, and with a lot of effort. Most of the images on my walls right now I printed myself. I could just never force myself to really concentrate on what I was doing. Better to let someone with an aptitude do it.

[PhilRich]

Here's a situation. In PS I resize the image to 360, however in the printer driver I set to the quality to super fine which for the Epson is 2880x1440. What do I get in the printed image - does the printer up the resolution? The resulting print shows very fine detail.

[TonyW]

I'm sure it would TonyW, my problem is I'd rather be shooting, and because my printing sessions are often 6 months apart, dry ink, forgetting how i got the results I got last time were achieved, and the fact that i rarely even tried to print unless I had a show deadline coming up, meant I really wasn't developing any proficiency. I'm sure a lot are in the same boat.

Don't get me wrong, I did gets some amazing results, but, not reliably, and with a lot of effort. Most of the images on my walls right now I printed myself. I could just never force myself to really concentrate on what I was doing. Better to let someone with an aptitude do it.

I seem to have misinterpreted the original post sorry normhead. Anyway never mind just shooting as you will have time to print when it goes dark and cloudy

Seriously I understand about ink clogging and wasting materials and a lot of money to put it right - I am in that situation now with an ageing HP Photosmart A3, I am trying to revive it and if I cant then I need to consider which printer to buy. Most pigment ink systems require a minimum throughput of prints to keep the channels open which is a waste which is made worse in my mind if you are only putting a low volume through on an irregular basis (at least financially)

---------- Post added 08-31-16 at 11:28 AM ----------

Here's a situation. In PS I resize the image to 360, however in the printer driver I set to the quality to super fine which for the Epson is 2880x1440. What do I get in the printed image - does the printer up the resolution? The resulting print shows very fine detail.

Best practice is I believe that you would only resample to 360 ppi if the ppi count fell below this figure by a reasonable margin at your desired print size. If at your desired print size ppi above 360 then you would set to 720ppi as this is what the printer expects. It is not considered to be best practice to downsample, say from 450 ppi to 360 ppi as you are throwing good data away, in this case you would go up to 720 ppi.

I will stress again that the viewing distance plays a role here as well as the quality of image content. Thing is that I have never met a photographer am. or pro. that will not walk up close to a print to examine it whatever its size and 'normal' viewing distance

The 2880x1440 refers to the amount of ink droplets whose size may vary and the way that they are applied to each pixel to form the image. I have not seen any recent explanations of how this is done - guess that is a company secret for the most part.

I believe that if you leave your image as it is and the ppi falls below the native resolution of 360 ppi for Epson then the printer driver must do the resizing to the expected 360 ppi using the drivers particular algorithms.

Your editing application will probably do a better job e.g. in Lightroom in the print module you may see something like 12" x 10" @ 96 ppi while you can send this to the printer as it is and probably get good results you may be leaving some IQ on the table therefore to address this you would tick the Print Resolution box and input 360 ppi - you would notice that the size is still shown but the ppi vanishes as you have overridden the native ppi for the print size with your own

[TonyW]

Just wanted to finish this with a couple of examples one containing reasonable data the other with not the best data to show the effects.

The poorer example first shot with a 1.9 MP point and shoot camera, no manual override of exposure or focus and JPEG only. This would print from original full size image 5"x4" @ 300 ppi
The full image with red rectangle showing the crop for printing.

Cropped area compared at 96ppi and 300 ppi image enlarged due to scan


On the actual prints there is very little to choose between either 300 ppi, marginally more detail in the boats name, the ladders and Yamaha engine but nothing to write home about.

So really garbage in garbage out regardless of ppi - maybe the image could have been massaged a little in post but I doubt a noticeable improvement to be had due to data limitations.

The next image from a 36 MP capture which would print @ 24"x16" @ 300 ppi from the native file.

This showing the image extents and the crop area used


The cropped scanned area from two prints one at 100 ppi and one at 300 ppi. It should be very obvious which is which.


The details that are improved e.g. the overall sharpness of the brickwork, the bridge cables and the telephone wires above the cables (missing completely from the 100 ppi image) give the printed image more of a three dimensional feel.

Viewing and comparing the images from a 'correct distance' of approx 43" there appears to be very little difference, other than perhaps better feeling of depth on the 300 ppi print. But moving closer reveals the improved details.

For me at least the answer is very clear. The difference more obvious than using a poor lens and comparing to a good one. If you are not worried about leaving image quality behind on the table then just print without worrying about ppi settings. But if you are concerned about presenting the best image you can then treat your data with care and respect.

[Adam]

Hi Alex, thanks for your interest to try and address your points at least based on my current understanding
My view is that 300 ppi is one of those myths that has permeated the net in particular, although probably has some basis in fact - I suspect that you are correct and and that this comes from the requirements for screen image and dot patterns.

A rough guide says if you are to print for a magazine at 150 LPI then 300 PPI equates to the same. What is really bad to hear IMO is that no one can see any image improvements over 300 ppi as that is the limit of human visual acuity. Clearly not the case as far as inkjet printing goes.

It is also irrelevant for many inkjet printers as some require 360 or 720 ppi i.e. Epson and ? whereas Canon and HP requirements are 300 and 600

Yes I could have made it clearer printed from the image at 600 ppi.

Just to be clear your camera capture does not have any size other than the number of pixels in the x and y directions i.e. native size. It only has a size when you declare such by picking the ppi you require for instance to print 150, 200, 240, 300, 360, 600 or 720 ppi - you can also pick the finished print size and the ppi (which may involve upsample/downsample).

To guarantee that you are getting the best from your data if the finished size does not come to your printers native ppi then you should probably upsample in your editor of choice rather than allow the printer driver to do this - remembering your printers requirements, in your case with Epson 360 or 720.

So really in your case with a finely detailed image there may be benefits to using 360 or 720 ppi. Your 1440 dpi printer setting is squirting up to 4 droplets of ink per pixel when you send it 360 ppi and 2 when you send it 720 ppi - in truth it is not quite that simple as inks will be overlaid but maybe a good way to think about it.

---------- Post added 08-30-16 at 12:02 PM ----------

You are spot on about distance viewing and in the other post I offered some ways to calculate what ppi required.

However it should also be born in mind that while you may have to accept that to get your print size from your native file size you will have to resample that it is not always ideal to just let the system get on with it as up to date printer processing algorithms inherent in the drivers do not seem to give as good a result as those from Adobe and perhaps LR in particular. There are other applications for printing that may be even better e.g. Qimage.

The bottom line seems to be if you have an image that has only 100 ppi to make a print of the required size then it will have to be upscaled somehow and you probably do not want to allow the OS or the printer driver to handle it when there are better options available

---------- Post added 08-30-16 at 12:04 PM ----------

OH dear seems to me someone has got out of the wrong side of the car today If you cannot see the relevance of what is posted fine - perhaps glasses are in order

---------- Post added 08-30-16 at 12:05 PM ----------

Thanks norm, I know that you were not over the moon with the initial results from your Canon printer. I really believe that it should be able to knock your socks off.

Good point. I'd go as far as saying that you should never let the driver resample. Always do it in your image editor, as that gives you access to more algorithms and manual control over the end result. If you use Photoshop for everything, for example, what you see will essentially be what you get as long as you're using a native DPI.