File size and printing large

[Hening Bettermann]

Help! I am all confused 😳
I have images I want to have printed large, 85x130 cm. I may want to edit after raw conversion before scaling for print.

I use Iridient Developer for raw conversion and scaling, PhotoLine for editing.

So in the output dialog of Iridient, I would choose 'scale to percent', say 20%. That gives 636 x 950 px (when I specify 96 ppi as screen resolution), 3,6 MB, 17x25 cm

Does this mean that only these pixels are affected by my editing (if any?)
The intended size is 85x126 cm, that is 3178 x 4762 px, 90 MB. How does the bulk of these pixels get my information? Do I have to edit at final size?

And:
If I specify screen resolution as 150 ppi, the image size is 4966 x 7441 px, 221 MB. How does the screen resolution come in?

Yes I too think this belongs in the Sandbox, but there doesn't seem to be much traffic there...
Thank you for your help, and good light!

[Slobodan Blagojevic]

What is the original size of the file?

Screen resolution is absolutely irrelevant for anything, except one thing (if I would explain that one exception, it might confuse you even more, so better forget about the screen resolution).

[digitaldog]

I wrote my first article for a magazine on Resolution way back in 1998, and I see it's still a topic of confusion today. FWIW, the article is archived here:
http://digitaldog.net/files/Resolution.pdf
After that, for print:
Jeff Schewe: The Right Resolution
https://www.dropbox.com/scl/fi/2uw6co0yb81l4uhhuxi8z/The-Right-Print-Resolution.pdf?rlkey=w9ncq43ltjffcn9karpq0c41x&dl=0

[Hening Bettermann]

Many thanks to the both of you!
Slobodan, the size of the original raw file is 37,5 MB, 4912 x 7360 pixel. -
Andrew, I will now read your sources.

[Slobodan Blagojevic]

Many thanks to the both of you!
Slobodan, the size of the original raw file is 37,5 MB, 4912 x 7360 pixel. -
...

130cm = 51 inch

So, 7360 px divided by 51 inch is 144 px/inch. That (144) is a printing resolution sufficient for say printing on canvas (I went as low as 100-120 for canvas, for a very good result).

The mantra for optimal resolution for paper printing is 300/360 px/inch (Canon/Epson). I personally find it overkill, but...

So, if you want a higher resolution for printing, specify 200% in your printing/scaling software, and you should be ok. Having said that, I am not familiar with the softare you mentioned, PhotoLine or Iridient, but math is math.

The workflow is you do all your editing at a native resolution of your file, and scale it up only at the printing stage.

The only variable might be sharpening, i.e., some might argue that final sharpening should be done after upscaling, but I have no experience with that, so will let Andrew or someone else more knowledgable on the topic comment. I personally never have issues with sharpening, beyond the two options in Lightroom, (Portrait and Landscape). Today's files, sensors, and lenses are so sharp that I often forget to sharpen files additionally (Lightroom does a certain default sharpening).

[Jonathan Cross]

As a simple soul, this has me a bit confused!  The OP talks about printing at 85x130cm.  At 300ppi this is nearly 154MP.  At 360ppi, even more. 

The most I print is 13x19", more usually 12x18" as my usual aspect ratio is 3x2.  At 300ppi this is between 19 and 20MP.  My camera is 40MP so if I have not cropped I just print straight from LR at 300ppi without any separate scaling; I assume LR will sort it, and I am happy with the output.  My camera does allow for some cropping room, but if on wildlife images, even with a 100-400mm lens, I often crop.  If the result is an image less than 20MP than I usually upscale.  LR super resolution is usually ok, but there are, of course, other ways.  I am too tight to pay for Gigapixel!  If I am sure that I will not print at bigger than the cropped size in the future then it does not seem to matter to me when in the editing process I upscale.  Usually I am not that confident so cropping is done at the end and I edit on the full image.  Sometimes I make a virtual copy so that I can experiment.

In this case it seems that to print at 85x130cm, upscaling would be necessary.  I would upscale early to have more than the MP needed for the print, and then do the editing, assuming the computer will handle it.  As far as what I see on the screen, that is determined by the screen resolution.  I am more concerned that I am processing what is needed for the print, and do not consider that I am just looking at a different resolution on the screen.

It seems to work for my eyes and those who see my prints, or am I being too simple and missing something critical?

Jonathan

 

[Hening Bettermann]

130cm = 51 inch

The only variable might be sharpening, i.e., some might argue that final sharpening should be done after upscaling,
[/quote]

Exactly that was my thought and plan - and my worry for the file size in MB.
In the article "The right print resolution", to which Andrew links, Jeff Schewe advocates to upscale the file to the native resolution of the printer. That would be 720 dpi at my print service on an Epson printer.

(The screen resolution came in probably because I entered it, maybe because PhotoLine uses it as the default if nothing else is specified.)

So I will now process one image and see how the file size will develop...

Raw file 37,5 MB
developed in Iridient,
including amongst others a little Richardson-Lucy deconvolution as capture sharpening.
saved at 100%, 72 dpi: 216,9 MB,  4912 x 7360 px

In real life, I would now edit in PhotoLine which uses its own file formate, use layers, then flatten to Tif. For now, I just open the newly converted image again in Iridient, which is my choice also  for scaling and sharpening. I apply a little  additional R-L deconvolution for now.

I have set resolution to 720 dpi, pixel size is now 23 837 x 35 717.

I want the print size to be: width unspecified (ca 85 cm) x height 126 cm.
To achieve that in Iridient, I have to set the size to "fit within" (100) x 126 cm. Result:
File size 4,29 Gigabyte. Process time ca 2-3 minutes.
But that is not during the editing, so it would be possible.
Question: Would it do harm to leave that scaling to the print service? Jeff Schewes article is 14 years old...

[Hening Bettermann]

It strikes me now: In the workflow as I describe it, nothing says that the output sharpening in the second run through Iridient is applied after upscaling, Iridient says nothing about the sequence under the hood. But independent of that, the question remains if the upscaling as a whole should be left to the print service.

@ Jonathan:
I can not judge if you are missing anything. You seem to do wildlife, my images are landscape, which may make a difference. -

[jrsforums]

130cm = 51 inch

So, 7360 px divided by 51 inch is 144 px/inch. That (144) is a printing resolution sufficient for say printing on canvas (I went as low as 100-120 for canvas, for a very good result).

The mantra for optimal resolution for paper printing is 300/360 px/inch (Canon/Epson). I personally find it overkill, but...

…maybe not “overkill”, but I agree you might not notice the difference.

It is not so much “optimal resolution”.  However, the printers expect the px/inch they want (Canon/Epson) and will scale the input if it is different.  It is optimal if you do not scale twice and that you use the best scaler possible (printer scalers and not).  Also, it is optimal to do output sharpening at final scaled resolution, which you cannot do if printer is scaling.

I would suggest OP consider Qimage, which will automatically scale output to printer/print size selected and uses highly sophisticated scalers with automatic output sharpening.

So, if you want a higher resolution for printing, specify 200% in your printing/scaling software, and you should be ok. Having said that, I am not familiar with the softare you mentioned, PhotoLine or Iridient, but math is math.

The workflow is you do all your editing at a native resolution of your file, and scale it up only at the printing stage.

The only variable might be sharpening, i.e., some might argue that final sharpening should be done after upscaling, but I have no experience with that, so will let Andrew or someone else more knowledgable on the topic comment. I personally never have issues with sharpening, beyond the two options in Lightroom, (Portrait and Landscape). Today's files, sensors, and lenses are so sharp that I often forget to sharpen files additionally (Lightroom does a certain default sharpening).

[Hening Bettermann]

I'm silly. Iridient does tell something about the sequence under the hood. During the 3 minutes mentioned, there is a progress indicator with a little text, and scaling took the major and last part of the time.

[Hening Bettermann]

John, thank you, I am considering Qimage.

[jrsforums]

John, thank you, I am considering Qimage.

It takes a little time to get used to (different UI, but not difficult) and Mike Chaney is always available on his forum to help.

What I do, in LRc/PS, is sharpen until it looks good to me (4K screen).  Send Tiff (full size jpeg ok for many) to Qimage.  I, then, can print at any or multiple sizes and Qimage does the scaling/sharpening for each size/printer).  If needed, you can +/- to sharpening amount to taste).

[mcbroomf]

The only variable might be sharpening, i.e., some might argue that final sharpening should be done after upscaling,


Exactly that was my thought and plan - and my worry for the file size in MB.
In the article "The right print resolution", to which Andrew links, Jeff Schewe advocates to upscale the file to the native resolution of the printer. That would be 720 dpi at my print service on an Epson printer.

(The screen resolution came in probably because I entered it, maybe because PhotoLine uses it as the default if nothing else is specified.)

So I will now process one image and see how the file size will develop...

Raw file 37,5 MB
developed in Iridient,
including amongst others a little Richardson-Lucy deconvolution as capture sharpening.
saved at 100%, 72 dpi: 216,9 MB,  4912 x 7360 px

In real life, I would now edit in PhotoLine which uses its own file formate, use layers, then flatten to Tif. For now, I just open the newly converted image again in Iridient, which is my choice also  for scaling and sharpening. I apply a little  additional R-L deconvolution for now.

I have set resolution to 720 dpi, pixel size is now 23 837 x 35 717.

I want the print size to be: width unspecified (ca 85 cm) x height 126 cm.
To achieve that in Iridient, I have to set the size to "fit within" (100) x 126 cm. Result:
File size 4,29 Gigabyte. Process time ca 2-3 minutes.
But that is not during the editing, so it would be possible.
Question: Would it do harm to leave that scaling to the print service? Jeff Schewes article is 14 years old...

You are mixing DOTS per inch with PIXELS per inch.  Scale to PIXELS per inch in your software (Epson is 360 or I think 300) but set the printer quality to 720 DOTS per inch. 

In older days when pixels were in short supply I was able to get very respectable prints using ~200 Pixels per inch. As I recall this came from Jeff and other luminaries (perhaps Michael) but don't hold me to that, just runs some tests at different resolutions.

[Hening Bettermann]

Thank you for chiming in. - Now I am confused again. This difference between 360 pixels and 720 dots - is this exactly the conversion that Jeff Schewe wonders: where is it done? nobody confesses to it; and that he recommends not to leave to the printer?

[digitaldog]

Thank you for chiming in. - Now I am confused again. This difference between 360 pixels and 720 dots - is this exactly the conversion that Jeff Schewe wonders: where is it done? nobody confesses to it; and that he recommends not to leave to the printer?

Printers make dots. Most often from pixels. This can be a 1:1 ratio (dots from pixels) or not. There is a unit per whatever; from a scanner or camera for example (pixels) or from a printer (dots).

[jrsforums]

Thank you for chiming in. - Now I am confused again. This difference between 360 pixels and 720 dots - is this exactly the conversion that Jeff Schewe wonders: where is it done? nobody confesses to it; and that he recommends not to leave to the printer?

Here's a breakdown of the differences between pixels and dots in the context of printers:
Pixels: Pixels are the fundamental building blocks of digital images displayed on screens. They are individual points of color or brightness that combine to form the overall image. The resolution of a digital image is measured in Pixels Per Inch (PPI), indicating the density of pixels within a given area. A higher PPI value generally corresponds to a more detailed and sharper image when viewed on a screen.
Dots: Dots are the physical units that printers use to reproduce digital images on paper or other physical media. The resolution of a printer is measured in Dots Per Inch (DPI), referring to the number of ink dots a printer can place within a one-inch space. A higher DPI generally results in a clearer and more detailed print because the printer can lay down more ink dots to reproduce the image.

Each printer still expects an input of a specific (300/360, for example) px/inch….and will scale the input if required.  It then uses this input stream to create dots/inch that you define in the quality settings of the driver. 

[Hening Bettermann]

Thank you both. Yes I was aware of the difference between pixels and dots, but not, that 360 of the one kind could translate to 720 of the other.
-Good light!

[mcbroomf]

Thank you both. Yes I was aware of the difference between pixels and dots, but not, that 360 of the one kind could translate to 720 of the other.
-Good light!

Well, it doesn't translate, (if I understand your use of the word) ie they are not connected as they are set separately/independently.  The file is set to say 360 PPI (pixels per inch) but then the print quality is set to whatever you feel like in the printer driver.  Some of the higher quality Epson printers on glossy paper can be set to 2880 DPI, yet you might still send a file set to 360 PPI to that printer.  If you look around there are probably many YT videos about whether anyone can see on a print the differences between 720, 1440 and 2880 DPI, and the higher settings in the print driver are not available on matt or canvas.

[Jonathan Cross]

Here's a breakdown of the differences between pixels and dots in the context of printers:
Pixels: Pixels are the fundamental building blocks of digital images displayed on screens. They are individual points of color or brightness that combine to form the overall image. The resolution of a digital image is measured in Pixels Per Inch (PPI), indicating the density of pixels within a given area. A higher PPI value generally corresponds to a more detailed and sharper image when viewed on a screen.
Dots: Dots are the physical units that printers use to reproduce digital images on paper or other physical media. The resolution of a printer is measured in Dots Per Inch (DPI), referring to the number of ink dots a printer can place within a one-inch space. A higher DPI generally results in a clearer and more detailed print because the printer can lay down more ink dots to reproduce the image.

Each printer still expects an input of a specific (300/360, for example) px/inch….and will scale the input if required.  It then uses this input stream to create dots/inch that you define in the quality settings of the driver. 

Just to add to this.

My Canon Pro300 pigment printer has 10 cartridges.  Each has 768 nozzles so a total of 7680 nozzles.  The printer can print up to 4800dpi horizontally and 2400dpi vertically.  The optimum printing for normal view is 300ppi.  I understand this is related to the resolving power of the eye when viewing at a certain distance and goes back to measurements done a long time ago.  The reason why dpi and ppi are different is because the printer will lay down different numbers of dots at a pixel site to get the image colour right.

There is a good account in an article on Keith Cooper's site:

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

I hope this helps, Hening.

Best wishes,

Jonathan

[Hening Bettermann]

Thank you for this useful information. In the meantime, my print service has confirmed, that "our" printer exspects 360 ppi input which it will "translate" to 720/1440 dpi on the paper - in this case. So no, "translate" does not mean a fixed relationship. 
Good light!