Mike Chaney's Tech Corner

A maybe more theoretical question: Is it possible to achieve the following in Qimage Ultimate:

Assumed I have a photo file of pixel size a,b (width, height) and I want to print this photo so that 1 pixel of the photo file corresponds to 1 pixel that my inkjet printer is able to produce (because of the nature of inkjet printers 1 printer pixel consists of one or more dithered ink droplets).

So, I disregard any resolution information that might be in my photo file and bring it more or less 1:1 onto paper. The advantage of this method would be that no resampling in any direction would be required since the printer's native resolution is used, and the photo file isn't rescaled in either direction up or down.

Besides of the question whether such is possible in Qimage Ultimate, I'd like to know if this kind of printing would result in the best possible quality (because of the lack of any transformation of the picture data) or if sampling would increase the quality of printouts.

I hope my question can be understood...

Andreas

It is my understanding that the driver or Qimage (Qimage preferred) will resample the image to match the required input PPI resolution.
As far as entering an image with original length in pixels and width in pixels, you can use ORIGINAL SIZE in custom, but you will have to set the PPI manually to 720 0r 360 or 600, depending on the printer's requirement.
Then the print size is determined by the resolution divided by the PPI.
You won't be able to select a print size on your own.

Fred

Andreas,
"Native Resolution" usually refers to the resolution tagged to an image by Photo Shop or similar. As Fred said QU can handle that as it's one of the Custom size settings.
I'm not sure how you would do that because you do not know the linear size of a printer pixel. I suspect you would end up with a very small print.
Certainly is  ::)
I suggest you don't worry about it and rely on Qimage to interpolate to the printer's native resolution and so prevent the driver interpoating. QU has THE most advanced interpolation method and enables you to print at the size you require without you having to bother about print resolutions at all - and get a top quality print.
Terry

I recently contacted Epson about "printer native resolution". In short they say there is no such thing. Also in one of Marrutt's videos he says the samething except explained differently.
This is the conversation with Epson's technical support:

Customer By Web Form 06/14/2020 11:45 AM
Many authors refer to "printer native resolution". Measured in pixels per inch. It is not the same as the dots per inch. What is the native resolution of my Stylus Photo R1900? How come is not in the specifications?


Response Via Email (Dyroza B.)   06/22/2020 02:55 PM
Dear Arturo,
 
Thank you for contacting Epson regarding your Epson Stylus Photo R1900. It is my pleasure to respond to your inquiry.
 
There seems to be some confusion, pixels are native to screens (i.e. TV, monitors, projectors), these are the small squares of color that make up the image on an electronic display and do not apply to printers.
 
Printers solely use DPI as a unit of measurement because they output dots (or droplets) of ink. One color channel consists of 360 nozzles, we are not aware of a "printer native resolution", but if we had to guess that would be the closest thing to that.

I believe that Mike gave you the best explanation possible. See above.
What he is saying is: If you set the driver to a quality setting that asks for 360 ppi, Qimage will interpolate the image and print size you gave it so the driver will get 360 ppi.
If on your Epson, you checked finest detail in the driver, depending on paper and quality settings, the  driver will ask for 720 ppi. Qimage will interpolate to 720 ppi. You might or might not SEE a difference.
You always want Qimage to do the interpolation; up sampling/ down sampling as the quality has been unmatched for 20 years.
Fred

I would not say "printer native resolution".  I would say "driver native resolution".  Qimage querries the driver for the following parameters:

Printable area X resolution
Printable area Y resolution
PPI X
PPI Y

The driver answers those querries by returning a "canvas" that is X resolution by Y resolution at PPI X and PPI Y.  So the printer is giving you a certain number of pixels to work with: that's the "native" driver resolution.  For example, you might be working in borderless on an 8x10 inch page.  An Epson driver might return these values when asked:

Printer X resolution: 5760
Printer Y resolution: 7200
PPI X: 720
PPI Y: 720

Even IF the driver didn't return any PPI (it has to: it's a Windows function)... it reports the physical width and height of the paper too: so if it returns a 5760 x 7200 pixel canvas to work with and says that the physical paper width is 8 inches and height is 10 inches, you know it's 720 PPI.  So if you ever hear me talking about "native PPI", that's the driver's "native" PPI.  If you send the driver anything other than 720 PPI in this case, it will internally resample to 720 PPI so it fits on the driver's defined canvas.  And again, you don't want to let the driver do that because it'll use a "cheap" interpolation method: at worse something like bilinear and at best, bicubic.

Mike