Why does a Canon printer claim to be able to print at 2400x1200dpi

[sanfairyanne]

On B+H's website they offer a high end Canon ImageProGGRAF TX-400 printer with claims it can print at 2400x1200dpi. When I go to my local printer he's likely going to tell me he'll print my image at 300dpi. When I think about this I'm going to guess I understand the difference. Please tell me if I"m wrong...

Ok so as I understand things if you asked a printer to put down one dot on a piece of paper it would actually appear to place down a single dot, but under close inspection that dot would be made up of a pattern of particles of ink. I came to the conclusion that there might be 32 particles of ink per dot when printing at 300dpi. I worked this out by multiplying 300x300=90,000. If you multiply 2400x1200dpi you get 2,880,000, divide this by 90k and you get 32.

If this is correct then I've finally figured something out for myself. If this is true I need to wrap my head around what happens if you ask the printer to print at 600dpi. Are you getting 64 particles of ink per dot?

Sorry to ask what might be an annoying question, I suppose most people don't give a damn about this sort of thing. For me it's part of the process of trying to learn about print resolution.

Many thanks in advance.

[Randy Carone]

When you say 300 dpi are you referring to the image dpi (really ppi) or the printer's dpi? I don't know the native resolution of Canon's but I send 360 ppi images to my Epson printer whenever I can, which has little to do with the printer printing at the max of 2880 x 1440 dpi. I sometime send an image of 180 ppi and also print at the same max resolution of 2880 x 1440 on the print.

[Rand47]

On B+H's website they offer a high end Canon ImageProGGRAF TX-400 printer with claims it can print at 2400x1200dpi. When I go to my local printer he's likely going to tell me he'll print my image at 300dpi. When I think about this I'm going to guess I understand the difference. Please tell me if I"m wrong...

Ok so as I understand things if you asked a printer to put down one dot on a piece of paper it would actually appear to place down a single dot, but under close inspection that dot would be made up of a pattern of particles of ink. I came to the conclusion that there might be 32 particles of ink per dot when printing at 300dpi. I worked this out by multiplying 300x300=90,000. If you multiply 2400x1200dpi you get 2,880,000, divide this by 90k and you get 32.

If this is correct then I've finally figured something out for myself. If this is true I need to wrap my head around what happens if you ask the printer to print at 600dpi. Are you getting 64 particles of ink per dot?

Sorry to ask what might be an annoying question, I suppose most people don't give a damn about this sort of thing. For me it's part of the process of trying to learn about print resolution.

Many thanks in advance.

Apples and oranges.   The number of dots per inch a printer can lay down, is not the same as the number of pixels per inch you send to the printer.

Read Jeff Schewe’s books, “The Digital Negative” and “The Digital Print.”

Rand

[mcbroomf]

It's not annoying and I'd hazard a guess that everyone who prints seriously gives a very big damn about it to make sure they get what they want/need in their print.

As Rand posted ...

Pixels Per Inch is set at the image level.  Take a look at Image > Image Size in Photoshop to see what dimensions you are getting for the given PPI.  It's simple math.  A 3000 pixel wide image printed at 300 Pixels Per Inch will yield a 10 inch wide print.  Resize if needed.
Dots Per Inch are set by the printer to give better continuous tones.  Photoshop has nothing to do with it.  It's set by the print driver (or RIP).  1200 DPI is fine, not sure you'll see the difference going up to 2400 DPI.

[enduser]

Our HP Designjet also has  dpi of 1200 x 2400.

[sanfairyanne]

It's not annoying and I'd hazard a guess that everyone who prints seriously gives a very big damn about it to make sure they get what they want/need in their print.

As Rand posted ...

Pixels Per Inch is set at the image level.  Take a look at Image > Image Size in Photoshop to see what dimensions you are getting for the given PPI.  It's simple math.  A 3000 pixel wide image printed at 300 Pixels Per Inch will yield a 10 inch wide print.  Resize if needed.
Dots Per Inch are set by the printer to give better continuous tones.  Photoshop has nothing to do with it.  It's set by the print driver (or RIP).  1200 DPI is fine, not sure you'll see the difference going up to 2400 DPI.

I understand that if I have a 3000px wide image I can print that at 10" width if I use 300 of my pixels for each inch of print. If I decide to print at 600ppi i'd get a 5" print, 1200ppi i'd get a 2½" print. So as Photoshop has nothing to do with the printers quoted DPI as this is managed by the RiP software the DPI must be making up a collage of ink particles for my print.

What I'm trying to understand is the correlation between 2400x1200dpi and each pixel. To expand on this, if I ask the printer to print at 1px per inch with a 3000px image I could make a 3000" print, but if we looked closely at each inch of print we wouldn't see just one dot on the paper, we'd see multiple particles (picolets) of ink.

Furthermore I'm trying to understand if we print at 1px per inch or 300px per inch does the printers RiP software change the number of particles relative to this?

I know some would say I'm over-thinking this, but to me it's important to understand.

[mcbroomf]

You set the DPI in the driver or RIP.  It's independent of the PPI used in the layout to define the size of the print.

[Jonathan Cross]

My understanding, right or wrong, is that if the printer is printing 300ppi in both directions and you have set 2400x1200dpi, then you are getting 32 dots per pixel.  Higher dpi leads to better colour gradations.  300 or 360ppi is usually taken as being small enough pixels that a 20/20 eye cannot detect them.

Jonathan

[sanfairyanne]

My understanding, right or wrong, is that if the printer is printing 300ppi in both directions and you have set 2400x1200dpi, then you are getting 32 dots per pixel.  Higher dpi leads to better colour gradations.  300 or 360ppi is usually taken as being small enough pixels that a 20/20 eye cannot detect them.

Jonathan

Thanks Jonathan,
This would imply that my initial calculation is correct, though I deliberately used the word 'particle' instead of dot because It's my understanding that when an inkjet printer prints it doesn't spray a defined dot, rather it sprays a pattern of ink. I looked at some images after Googling 'inkjet print under extreme magnification'.

[Doug Gray]

This thread discusses printer rolloff, DPI and PPI.

https://forum.luminous-landscape.com/index.php?topic=126683.0

[deanwork]

The so called “ black box” of the printer driver is laying down variable sized dots of the pigment printer proprietary formulas as I understand it and does not equate in a regular grid of dots per inch. Different colors and different tonal values are often mixed and overlapped in the most efficient ways.

 Dpi is terminology is more a legacy term that relates to the analogue world of offset printing. In years past we shot halftone screens of continuous tone photographs to make our printing plates from, which actually did consist of 300 pure black dots per inch that at a distance were blended by the eyes to produce the illusion of tonality. These days it’s more a matter of file size that allows the greater resolution capability. All this is also confounded by the particular application source used to do the output, such as Photoshop, Raw files from Lightroom, and various rips or or other printer apps that alter the way the ink is laid down and overlapped on the paper ( dither). And the particular brand and generation of printhead plays a role.

This thread discusses printer rolloff, DPI and PPI.

https://forum.luminous-landscape.com/index.php?topic=126683.0

[sanfairyanne]

The so called “ black box” of the printer driver is laying down variable sized dots of the pigment printer proprietary formulas as I understand it and does not equate in a regular grid of dots per inch. Different colors and different tonal values are often mixed and overlapped in the most efficient ways.

 Dpi is terminology is more a legacy term that relates to the analogue world of offset printing. In years past we shot halftone screens of continuous tone photographs to make our printing plates from, which actually did consist of 300 pure black dots per inch that at a distance were blended by the eyes to produce the illusion of tonality. These days it’s more a matter of file size that allows the greater resolution capability. All this is also confounded by the particular application source used to do the output, such as Photoshop, Raw files from Lightroom, and various rips or or other printer apps that alter the way the ink is laid down and overlapped on the paper ( dither). And the particular brand and generation of printhead plays a role.

Thanks Deanwork, I'll check the link out. I've been out shooting today, I was out hiking which I find always a good activity to let the brain flow. I was thinking that the terminology is confusing and I can suppose if it comes from an analogue world that would explain things. I'm going to try to remember that when we tell our printer to print at 300 or maybe 360 dpi this should not be confused with what the printer nozzles spit out. I'm visualising the printer spraying particles of ink based on the rip software to create the dither. When I see a printer quoting 2400x1200dpi I think I'll understand this to mean particles of ink that make up the dither.
When I read my replies I'm not sure I'm doing the best job of explaining my thoughts, but I think I'm understanding the process.
I'll check the link now.

[Randy Carone]

Please - dots not particles. Ink does have particles in suspension but I don't think this is what you mean. In a thread as nuanced as this one, proper terminology is important.

[nirpat89]

Please - dots not particles. Ink does have particles in suspension but I don't think this is what you mean. In a thread as nuanced as this one, proper terminology is important.

Actual pigment particles (colloidal in nature) are to the tune of nanometers (50 to 200) while the dot size can be in the microns. 

Here is a good article that explains the difference between various terms:

http://www.rags-int-inc.com/phototechstuff/epson2200/

:Niranjan.