Printer limits

[Testor]

I have noticed that most of the photo stores print my digital photos on a wide pro-looking Epson printer. It looks like it has 10 or so ink cartridges. They have rolls of photo paper that they can change and I assume they are Matte or Glossy or whatever... canvas too I think. My question is this: Does the maximum resolution of the printer limit the necessary resolution of the file? If so what is that limit? As a follow on these printers are ink-jets (even if they call themselves giclee) and not analog. The have a digital device of some kind to position the nozzle exactly. I am guessing this is accomplished by a disk encoder on a ball screw shaft. But whatever it is it is digital not analog. It cannot therefore approach film in resolution. Right? Actually this is two questions. I hope it does not scatter with replies because I would like to know the answers to both. Testor

 

[Garbz]

The resolution of your file and the resolution of the printer are two different things. A file is made up of pixels, each pixel is made up of red green and blue data and that one pixel could be any one of 16million different colours (depending on the bitdepth of the image). A printer relies on halftoning a few primary colours to achieve a specific colour. The individual dots laid down can only have the colour of a combination of what ink is available (9 combinations for a 3 colour inkjet).

The pixels in your picture need to be small enough so as to not be resolved by your eye. The practical limit for this changes but typically we're talking 300pixels per inch as being a golden standard for photographs which at a normal viewing distance for a 6x4 will not show any pixellation.

The dots a printer need to put down are typically an order of magnitude finer. A typical professional grade printer will print 2880 dots per inch. The only time you'll visibly see these is under a microscope. What is critical is that these numbers are needed so that the printer can approximate the 16million possible colours of your pixel by putting various dots on top of each other or next to each other.

With this in mind the resolution of the printer has no relation to the resolution of the file. Obviously when you take it to horrendous extremes and print a 1000ppi image and set the printer to lay down 300dpi (draft mode) then obviously the printer will be limiting, but ultimately through interpolation it is practically impossible for printer to be the limiting factor of a photograph. For somethings yes, but not for what we can hope to visually see with the unaided eye.


Now to the notion of film "resolution". Film doesn't have resolution. It has grain. It's probably best thought of has halftoning dots again. But the important part is what you're trying to compare. A sheet of photographic film can be cut to arbitrary sizes. This makes it theoretically impossible for anything digital to approach the resolution of film as the sensor can be made arbitrary in size. That said I have yet to see a 100% tac sharp 24mpxl scan of a negative, so one way or the other digital cameras have surpassed film in terms of usable resolution in a small area. This is also taking into account the ideal scenarios for film. ISO800 film would be bested by pretty much every digital camera currently on the market. Most films are bested by many of the cameras in terms of colour quality and accuracy. And EVERY film is bested by digital cameras in terms of linearity due to a lack of reciprocity failure in digital sensors.

As for the mechanics of printer... it's capable of dropping 2880 dots per inch. No film in the world has a grain as fine as the dots placed on the paper by the printer. Also a print head has many ink jets on it which mean the digital part of the printer's control system does not need to be able to guide a print head to 1/2880th of an inch. That said if it were required it would just be a case of gearing.

I believe you've come into this thread seeking some kind of affirmation that film is better than digital. My personal opinion is that this hasn't been a case for a while now even under ideal situations.

 

[BlueMeanieTSi]

To answer your first question, if they are using Epson printers your PPI for your print needs to be 360 (or a multiple of such) to achieve the proper detail.

 

[Ysarex83 77]

To answer your first question, if they are using Epson printers your PPI for your print needs to be 360 (or a multiple of such) to achieve the proper detail.

That assumes the printer's resolution is 2880 dpi. It's not. Current Epson printers have a resolution of 2880 x 1440. It's a pain to keep writing that "x 1440" and after awhile it gets dropped. Epson loves that and maybe encourages it some. The printer's "real" resolution has to be determine from both those figures.

Joe

 

[KmH]

To answer your first question, if they are using Epson printers your PPI for your print needs to be 360 (or a multiple of such) to achieve the proper detail.

Some research indicates that is an urban legend. For example, the information in this article relative to your statement - Getting Started With Inkjet Printing

Applying some logic would also indicate it is questionable information.

Additionally, as print size increases, so does print viewing distance, and as viewing distance increases the density of the PPI assigned to the print can be reduced. Consequently, the PPI a print needs to be assigned is a moving target.

Quite a few pro print labs are willing to stake their reputations on printing any size print at as low as 100 PPI.

 

[BlueMeanieTSi]

Epson printers require at least 180, according to their tech support 180/360/720 will all work however you will get moire patterns if you don't choose the correct ppi for those printers. I will post an example.

 

[BlueMeanieTSi]

ACtually scratch that, I am low on ink and it's still set to print on matte paper so I'm not going to waste it right now.

 

[Testor]

The resolution of your file and the resolution of the printer are two different things. A file is made up of pixels, each pixel is made up of red green and blue data and that one pixel could be any one of 16million different colours (depending on the bitdepth of the image). A printer relies on halftoning a few primary colours to achieve a specific colour. The individual dots laid down can only have the colour of a combination of what ink is available (9 combinations for a 3 colour inkjet). The pixels in your picture need to be small enough so as to not be resolved by your eye. The practical limit for this changes but typically we're talking 300pixels per inch as being a golden standard for photographs which at a normal viewing distance for a 6x4 will not show any pixellation. The dots a printer need to put down are typically an order of magnitude finer. A typical professional grade printer will print 2880 dots per inch. The only time you'll visibly see these is under a microscope. What is critical is that these numbers are needed so that the printer can approximate the 16million possible colours of your pixel by putting various dots on top of each other or next to each other. With this in mind the resolution of the printer has no relation to the resolution of the file. Obviously when you take it to horrendous extremes and print a 1000ppi image and set the printer to lay down 300dpi (draft mode) then obviously the printer will be limiting, but ultimately through interpolation it is practically impossible for printer to be the limiting factor of a photograph. For somethings yes, but not for what we can hope to visually see with the unaided eye. Now to the notion of film "resolution". Film doesn't have resolution. It has grain. It's probably best thought of has halftoning dots again. But the important part is what you're trying to compare. A sheet of photographic film can be cut to arbitrary sizes. This makes it theoretically impossible for anything digital to approach the resolution of film as the sensor can be made arbitrary in size. That said I have yet to see a 100% tac sharp 24mpxl scan of a negative, so one way or the other digital cameras have surpassed film in terms of usable resolution in a small area. This is also taking into account the ideal scenarios for film. ISO800 film would be bested by pretty much every digital camera currently on the market. Most films are bested by many of the cameras in terms of colour quality and accuracy. And EVERY film is bested by digital cameras in terms of linearity due to a lack of reciprocity failure in digital sensors. As for the mechanics of printer... it's capable of dropping 2880 dots per inch. No film in the world has a grain as fine as the dots placed on the paper by the printer. Also a print head has many ink jets on it which mean the digital part of the printer's control system does not need to be able to guide a print head to 1/2880th of an inch. That said if it were required it would just be a case of gearing. I believe you've come into this thread seeking some kind of affirmation that film is better than digital. My personal opinion is that this hasn't been a case for a while now even under ideal situations.

You are full of great information. Not too good at reading the crystal ball though I want to know the stuff you just told me and you have given me much more to research, thank you. I think I will looking into the electromechanics of ink-jet more deeply now since what you seem to be describing is an analog output (not discreet positioning) from a digital input... fascinating. I have been a photographer for half a century and a videographer for half of that. We have been using Photoshop since it's inception and used what? CMX? before that. I forgot the name of it.. so long ago. I take an occasional "artsy" black and white on my Rolle but have been 100% digital for almost ten years now.