Upsampling image and printing native ppi vs printer ppi

[TonyW]

Stemming from a discussion elsewhere about printing and what PPI to send to the printer with one person claiming you really do not need to send more than 100 PPI to the printer (any printer) to get a decent result and me saying that ideally you should be sending at your printers native PPI either Epson or Canon and upping the file resolution if necessary rather than allowing the print driver to do this.  Basically what Jeff Schewe has been recommending, at least as far as I recall.

This has been my habit for quite some time now and using an aging HP B9180 (or entry level Canon A4 for the odd 6x4 holiday snap) have been generally quite satisfied always sending either 300 PPI or 600 PPI and either upsampling in PS or more recently LR, and consequently not recently done any comparison with just allowing the printer driver to get on with it vs sending upsampled data - until recently.

I originally posted Here but in an effort to be brief did not explain clearly and as it was a bit of a hijack decided to go into more detail and show an example or two.

Basically I was surprised by the improvement obtained printing a small crop at native resolution vs upsampling to printer PPI.  TBH, I did not expect to see such a large IQ improvement and has caused me to question, my method, the  printer etc. and ask here if what I am seeing is to be expected. 

I thought that it would be best to show a couple of images to enable you to see where I am coming from:

The original image a 7 shot hand held pano. I am trying to decide if I like it enough to actually print large after cropping some more of the foreground.  I have been trying to get a better shot with more foreground interest but so far after several visits no luck


An individual frame with ROI highlighted


Outputting from LR I made two small prints of the cropped area measuring 7.45"x 4.40". One at the crop native resolution as shown by LR of 107 PPI and the next by selecting the print resolution 300 PPI manually, both on the same entry level A4 Canon printer.  For both prints set LR sharpening to low and glossy paper (actually used Canon Semi gloss) and just allowed the printer to colour manage.  To enable comparison to be seen here did a quick scan of both images (all scanner sharpening and effects turned off) and combined in PS and Save for Web.  I know the colour is way off but the difference in resolving detail between the two is what I am really interested in and the comparison seen here is pretty much what I see in the print when viewed closer than about 2 '.  Viewing any farther away than this then the difference as expected soon vanish
.

So after all that my questions are:
Considering the crop native resolution of 107 PPI would you expect to see such a difference after upsampling to printers native 300 PPI?
As LR has limited user control of output sharpening am I correct in assuming that there would be a change in both radius and amount between 107 and 300 PPI?
If that is the case does it fully account for the difference?
Or
Have I just somehow fouled up somewhere and the difference you would expect to see is smaller than my examples ?

I know that this is somewhat lazy and I should revisit this to confirm but I would appreciate your comments 

[disneytoy]

I'm guess the second print is the lightroom upscaled?

Been there, done that. You are always better off using Lightroom or PS to small to you printers resolution. Mine is 360 dpi on a 9890.

When the printer driver/hardware upscaled, it uses is the fastest less optimal algorithms.

I've tried all the upscaling plugins and your best bet is out of lightroom print module, or upscale in the latest PS. Print from PS, or then print from LR with scaling turned off.

I've printed thousands of feet with these techniques.

Good luck!

Max

[Fulvio Senore]

IMHO the sharpness difference is too large for a simple change in resizing algorithm.

I don't use Lightroom so I cannot comment your steps, but it looks like in the "native" print the image has been downscaled in some way, so effectively dropping a lot of pixels. Then it has been enlarged again but the lost pixels cannot be recreated so the image lacks resolution.

Fulvio Senore

[digitaldog]

Stemming from a discussion elsewhere about printing and what PPI to send to the printer with one person claiming you really do not need to send more than 100 PPI to the printer (any printer) to get a decent result and me saying that ideally you should be sending at your printers native PPI either Epson or Canon and upping the file resolution if necessary rather than allowing the print driver to do this.  Basically what Jeff Schewe has been recommending, at least as far as I recall.

Double that value to 200 (maybe 180PPI), perhaps. 100 PPI? Nope.
Back in the very, very early days of printing digital images (around 1993) I purchased a used Kodak XL-7700 printer for $10K. This was one of the first if not they first true, contone digital printers, originally developed as a rack mounted unit for the military. It's output resolution was 203DPI. Odd number. Why? Kodak felt that was the minimum to produce acceptable results and keep in mind, this was a dye sub unit and back then, a 10x10 image at 203PPI was considered a big file.

Considering the crop native resolution of 107 PPI would you expect to see such a difference after upsampling to printers native 300 PPI?
As LR has limited user control of output sharpening am I correct in assuming that there would be a change in both radius and amount between 107 and 300 PPI?

The sharpening is resolution dependent so keep that in mind. You might consider doing the tests outside of LR who's resampling is also a tad better than Photoshop, again, adaptive and resolution dependent if you want a closer 'apples to apples' comparison. Or not and consider the resampling and sharpening in LR a plus if you will.

[kers]

... It's output resolution was 203DPI. Odd number. Why? Kodak felt that was the minimum to produce acceptable results and keep in mind, this was a dye sub unit and back then, a 10x10 image at 203PPI was considered a big file...

The number in not so odd if you realize it is 80dots per centimeter...

[TonyW]

Max, thank you and yes the second is the LR upscaled. 

Fulvio, thanks and my feeling is the same that the difference too large and I have made an error somewhere

Andrew, exactly my thoughts 100 PPI not optimal (but I guess it must really depend on having good data to begin with including fine detail).  I never came across the older digital printers,  $10K used wow, even more wow going back to 1993! 
Thanks for confirming the sharpening is resolution dependent, so my quess is that radius may be around 1/100 of image PPI count and amount depending on Low, Standard and High settings and paper type, but I guess that is proprietary info anyway.
I strongly suspect that I have missed something in my first test and the gains would be somewhat less depending on input detail and quality. 

[digitaldog]

The number in not so odd if you realize it is 80dots per centimeter...

Of odder still that Kodak, an American company, making a printer for US tanks would use dots per centimeter but you have a point. 

[disneytoy]

I have a printing business. I often prin 24x36" or 40x60" at 100 dpi. They look fine at those sizes and viewing distances. Remember 36,42 an 50mpx cameras are relatively new. I shoot an a7rii and those 42mpx files make wonderful 40x60" prints

[Bart_van_der_Wolf]

I have a printing business. I often prin 24x36" or 40x60" at 100 dpi. They look fine at those sizes and viewing distances.

Hi,

100 PPI is not much, unless viewed from 3-6x the normal (say 10-12 inches) reading distance. And even then, there is a difference with properly upsampled images to match the printer's native resolution, even if they start at 100 PPI. Here are some example Crops, upsampled to 450% to match the printer's resolution.

Cheers,
Bart

[TonyW]

I have a printing business. I often prin 24x36" or 40x60" at 100 dpi. They look fine at those sizes and viewing distances. Remember 36,42 an 50mpx cameras are relatively new. I shoot an a7rii and those 42mpx files make wonderful 40x60" prints

Hi Max,
No way was I suggesting that you could not get excellent images if your native file resolution turns out to be limited to 100 PPI at your required print size. 

Based on my current understanding and as mentioned earlier just sending 100 PPI to the printer direct is sub optimal which may be attributable to the 'inferior' algorithms used by the printer manufacturers to send the data as required e.g. 300/600 PPI Canon/HP and 360/720 PPI Epson (regardless of the file native PPI).  At least this should hold true when compared to the more specialised algorithms used in LR, PS and maybe even more so for specialised printing applications such as Qimage etc.

Again based on my current understanding for occasions when I require to know what PPI needed (under decent illumination for those with 20/20 vision).  I would calculate using 1/(D*TAN(0.00029089)) to get an idea of minimum PPI requirements - D= viewing distance in inches. 

In the case of only having a native file resolution of 100 PPI it works out that you really want to be viewing at no closer than 34.5" (34.5 * TAN(0.00029089) = 0.0100357052831= 99.6 PPI).
 
The viewing distance which you may want to calculate first would be calculated based on 1.5-2x the print diagonal so for your 24x36" print you would be looking at a minimum viewing distance of 65" and 53 PPI (@ 1.5x diagonal).  So in my case I would be upsampling to 300 PPI for HP and you would use 360 PPI for Epson.

I only mention these calculations based on my understanding and take the risk that I could be wrong, with the knowledge that if this is the case someone here will correct me PDQ

Getting back to my original query I have not repeated the experiment, apart from running out of A4 photo paper I still suspect that I did something wrong in LR to show such a difference and I will probably revisit when I get my old HP running again or replace it

[disneytoy]

Bottom line, Lightroom print module does a very good job of optimizing the image to the printer resolution. Photoshop manual image size adjustment is great, but more work. I don't think PS has the same output option when printing.

[Ajoy Roy]

ON1 Resize, upscale based on the printer ppi the source files size and the target print dimensions. It uses 300 for HP and 360 for Epson printers. These are the resolutions that most commercial print houses in India recommend.

One thing to note is that large print houses for some printers, use special "Raster Processing" software and dedicated hardware to optimize the print runs. When they use printers with these facilities, they advise the user to leave the photographs at their native resolution, as their system will upsize and match the printer requirements much better.