dpi question

In my reading it is mentioned that 240 to 300 dpi on one's printer is the goal for prints. Yet when I read the specs for my printer the figure of 4800 dpi is always mentioned. How do I compute that?
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nbinpt said:

In my reading it is mentioned that 240 to 300 dpi on one's printer is the goal for prints. Yet when I read the specs for my printer the figure of 4800 dpi is always mentioned. How do I compute that?

Click to expand...

The surface of the printed page is made up of a lot of tiny specks of ink.

The (high) 4800dpi [ dpi = dots per inch = printer quality setting ] figure means that a fine spray instead of a coarse ink spray is used, when putting a particular mixed colour on each part of the paper.

The colour of this spray needs to vary in different parts of the paper, in order to represent the photo. If the photo provided only 1 pixel per square inch of the print (1 ppi), then you'd see a same-coloured spray over the whole of this square inch, and a differently-coloured spray over each adjoining square inch. This would make a very undetailed-looking print, compared with another photo that had 100 differently coloured pixel squares to be sprayed into each square inch (100 ppi), or 240, or whatever - each one with a discrete colour, the more of these, the more finely the colour ink spray can represent photographic detail. [ ppi = pixels per inch = quantity of supplied picture information]. A finer spray (dpi) may be slightly better at putting this into practice than a less fine spray would, but this will only really show up for very distinct contrasty edges and very fine patterns in the photo.

RP

nbinpt said:

In my reading it is mentioned that 240 to 300 dpi on one's printer is the goal for prints. Yet when I read the specs for my printer the figure of 4800 dpi is always mentioned. How do I compute that?
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Click to expand...

You are confusing DPI , dots per inch, with PPI , pixels per inch. Your image is displayed on your monitor in PPI, pixels per inch. The printer prints by placing dots of ink, DPI , dots per inch. It is recommended that you size your image for printing in Photoshop or other editor somewhere between 240 PPI , pixels per inch, and 360 PPI , although I find prints will often look just fine with much less PPI.

Your printer and/or printing software will then take care of the DPI , dots per inch, select "best photo" or whatever your printer driver has for highest quality.

CaseyJ

I understand the difference between ppi and dpi but in the book I'm reading he refers to printing at 240 to 300 dpi's. A misprint? But this is Ben Long's "Digital Photography" which is a really good book. Is this a misprint and am I having a senior moment?
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I have an Epson 3800, and can get away with as low as 180 dpi when printing.

240 to to 300 is preferred, but if I only have a 180 dpi image at the size I want, I can get away with.. Heck , I have some images that I have gotten away with less than 180 dpi with images without a lot of detail...

i would suggest making some test prints- printing the same files at various dpi, and comparing the results. (300.180, 240, 200, 180 150). theni nspect the prints. to see how low you can go with results that you find acceptable... I usually print with 240-300 dpi when possible, and only print lower when necessary..
Buzz

I think I have been wrongly interpreting what Long is saying in his book. He says one should use a 300 dpi for the printer and it sounded to me like it was a setting in the printer itself.

For instance he says, "if the optimum resolution for your printer is 240..." and I read that as a figure that was a setting for the printer itself.
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nbinpt said:

I think I have been wrongly interpreting what Long is saying in his book. He says one should use a 300 dpi for the printer and it sounded to me like it was a setting in the printer itself.

For instance he says, "if the optimum resolution for your printer is 240..." and I read that as a figure that was a setting for the printer itself.
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Click to expand...

You need to determine the true native DPI for your printer brand and model. Most Epson printers seem to have a native DPI of a multiple of 360, ie; 720, 1440, 2880, etc. Many "experts" recommend you set the PPI to the same or at least a multiple of the native DPI of your printer. Using the 4800 DPI stated in your original post for your printer then you would want to size your image in the editor to 240 PPI or a multiple thereof as 240 is divided equally into 4800 DPI. Supposedly prevents the printer driver from having to interpolate the image PPI to a multiple of the printer DPI . Some printing software such as Qimage will automatically set the image PPI to the required multiple for the printer used. Generally the quality setting used for your printer determines the number of Dots per Inch used. It will always be a multiple of the native DPI of you printer regardless of the final number.

CaseyJ

Thank you, Casey. That's good info. I found under the "best' setting for print quality that it gave 600 dpi, and under maximum it said 2400 dpi. But I would imagine that I wouldn't need that for just note cards?????
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DPI and PPI are used interchangeably these days yes I knnow the difference between dots per inch and pixels per inch. Inkjet printers do not have any native resolution they can print at any resolution up to their maximum resolution. I'm sure if you look at your 4880 manual that will be listed something like 2880 x 1440 not even square. When you set 2880, 1440, 720 etc you setting a quality setting. To be able to use 2880 you need to be using quality photo paper. If you using something like ink jet paper 2880 will not even be an option for it would oversaturate the paper and bebome water logged. Ink jet printers print at the Images resolution like 300, 240, 580 etc. They deposit many drops of ink into to the images pixels to produce a pixel of the correct size and color. They use their higher resolution capabilities to paint in your images pixels. The higher quality print setting produce higher quality pixels but take a longer to print and uses more ink. You will read others writing about native resolution of your printer challenge them to find that term native resolution in your manual or preferred picture input resolution perhaps even print resolution etc. I think all they will find is max resolution and print quality settings expressed as dpi.
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JJMack