Om printed media like inktjet based printer Epson 2200, 7600 or led printers like a fuji frontier there is a certain maximum number of pixels these printes can print on a inch.

The maximum dots per inch (dpi or ppi ) is not always easy to find or understand.

Fot inkjet printer like the Epson 2200 the only way to find out is to print a photo with different amount of dpi and compare the prints carefully.

You can easyly do it yourself.

Althought the Epson 2200 is widely regarded as a substitude for darkroom prints there is littly known of the real dpi this printer can achieve. Ideally this printer should do at least 300 dpi but 400 dpi would be perfect.

How many dots are on a photo?

Because inkjet printers have to place a lot of dots together to simulate a certain color it is hard to predict the real number of dpi inkjet printers can achieve.

dpi, ppi

There is some misunderstanding about the terms. DPI is the numer of dos in a inch. A epson inkjet will do 1440 dos in a inch. However there the printer cann ot make dots in any color or darkness. The printer needs some dots together to make the perfect color. The dots are placed in a grid. In the case of the Epson 2100 it uses problably a grid of 5x5. So of the 1440 dots in a inch we have 1440 / 5 - 288 usefull dots. The term PPI is used for real , different dots.

so The epson is 228 dots. The term fot this technique is ditthering. Mixing a lot of dots together to make a color.

There are also printers which use a continuous color mechnism. Every dot can get every color and intensity. Laser printers like the fuji frontier use this system.

Test 1, Epson 2100 LPI

To test this i printed this picture on a 8x10 inch (20x25cm) with several dpi. The same photo was send to the epson 220 with a resolution of;

The prints where viewed with the bare eye under daylight and 5500K normlight TL. There is some difference visible between the 150 and 300 dpi prints. Between 225 and 300 hardly any difference is visible.

This first test shows the Epson 2200 seems capable of printing a more or less 225dpi. The differences are small. Maybe to small if this printer is really capable to print more than 150 dpi.

Test 2 , Fuji Fronter LPI

The second test consist of 3 prints made on a fuji frontier 355. The frontier line of printers should be capable of a resolution of 300 dpi. Because the frontier uses normal photopaper with 3 color layers every dots can consist of a separate color. The is no need to use more than one dot to make a certain color.

We printed a 8x12 inch (20x30cm) with sevaral dpi's

This time the differece between the 3 prints is much greater than in the test with the epson 2200. There seems a huge difference between the 150 and 300 dpi print. The 150 dpi seems sharp but maybe a little bit soft. The 300 dpi is very sharp, crisp. The difference between the 200 dpi and 300 dpi is of cource less dramatic but can be clearly seen.

This is of course not a scientific test but is made one thing clear;

• The Epson 2200 is problably capable of printing at 150-225 dpi.
  
• The fuji frontier can print as high as 300 dpi.
  
  

Durst Lambda

I plan to do some future test with prints made on a durst lambda with 400 dpi.

a problem with printing is the reality that some labs consider 200 dpi as high enough for quality prints. The durst lambda laser printer has the capacity to make prints on 200 or 400 dpi. Of cource it is faster to print on 200 dpi. Some labs do print on this lower value. Problably it is faster and good enough.