I’m not really sure how to correlate between ppi and dpi either. But generally speaking, from what I have been able to ascertain, somewhere between 240 and 300 PPI seems to be about the most any of the inkjet printers can handle. I use an HP printer. Since I use a five megapixel camera my image dimensions are like 36 inches by 27 inches at 72 PPI. I have had pretty good success leaving the dimensions alone, including the resolution, and then just selecting the "scale to fit media" checkbox on the Elements print preview dialog box.
I recon that a six color inkjet printer splashes at least six color ink (CcMmYK) droplets per pixel; thus a 2880×1440 printer may print at most 2880/6=480 pixels per inch of paper horizontally, and 1440/6=240 pixels per inch of paper vertically. As Jim Hess said above, 240-300 ppi file resolution is within the range, with 200 ppi as the lower bound.
Tomaz
a 2880×1440 printer may print at most 2880/6=480 pixels per inch of paper
horizontally<<
You can’t print c and C or m and M at the same place, so the figure to divide by is 4 not 6.
Also the 2880 is achieved by ‘double-stepping’ to avoid horizontal banding. Ignore it and use the 1440 figure.
However, in FM screening the required image rez is determined by the dot-size and NOT the number of dots in a physical area or linear length, which varies according to image density.
DJ_Horton,
In most cases you will see no improvement with image ppi’s above 200. If there is very fine detail (Guitar strings, telegraph wires, sailing ship rigging etc.) an increase to 300 ppi MAY achieve a visible improvement in those areas.
DJH
First off, make sure that when you are changing size/resolution of pictures, you have resample unchecked. 300ppi is a good rule of thumb. Down to 200ppi, will usually be OK. Higher values are generally harmless.
I too have a Sony 5mpx camera [717] and I think the images are set as 72ppi, but are very, very large in inches. I can often print a full frame up to about A3 paper size, with very acceptable quality. This is around 175ppi, I seem to recall.
I thought that 360 ppi was the best resolution when using the 2100/2200… or at least using a multiple of the resolution 288 ppi could be worth checking too…
at least using a multiple of the resolution 288 ppi could be worth checking too
Interesting idea. But how many dots are used to represent each pixel is, I believe, rather less simple than that.
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I’m not really sure how to correlate between ppi and dpi either. But
generally speaking, from what I have been able to ascertain, somewhere between 240 and 300 PPI seems to be about the most any of the inkjet printers can handle. I use an HP printer. Since I use a five megapixel camera my image dimensions are like 36 inches by 27 inches at 72 PPI. I have had pretty good success leaving the dimensions alone, including the resolution, and then just selecting the "scale to fit media" checkbox on the Elements print preview dialog box.
You may find the Image Size and Resolution of my Tips on Scanning page useful:
http://www.pgacon.com/tips_on_scanning.htm Peter Aitken
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DJH
First off, make sure that when you are changing size/resolution of
pictures, you have resample unchecked. 300ppi is a good rule of thumb. Down to 200ppi, will usually be OK. Higher values are generally harmless.
PPI values are COMPLETELY MEANINGLESS when printing (and, with the exception of scanning, for everything else). They affect only the print size if and only if you print at 100%. For example:
1000 x 1500 pixel image at 100 ppi has a "size" of 10×15 inches. Print at 100% to get a 10×15 print.
The same image with ppi changed to 300 ppi (without resampling) now has a "size" of 3.3×5 inches. Print at 300% to get the exact same 10×15 print.
—
Peter Aitken
Remove the crap from my email address before using.
I recon that a six color inkjet printer splashes at least six color ink (CcMmYK) droplets per pixel; thus a 2880×1440 printer may print at most 2880/6=480 pixels per inch of paper horizontally, and 1440/6=240 pixels per inch of paper vertically.
If only it were that simple…
1) There are usually more than one dot of any given colour used for a single pixel.
2) Two different colours can be printed one over teh other (that’s how you get rich black.
I think part would depend upon the paper you use with the 2200.
When I was using a 1270 and Prem. Glossy paper 360 LPI gave slightly better results. I do mean SLIGHT. But it was there and I used that "setting" in the files.
I don’t use that paper with my 2200. I can’t see a difference between 300 & 360 LPI with Luster, Semi-Matte, or Enhanced Matte papers. Perhaps it is just the extra couple of years of eye strain showing up or the paper texture over shadows any gain.
That is with a naked print. Once behind non-reflective glass and viewed at a regular distance for the 13 x 19 inch paper, I doubt sharper eyes than mine would see a difference. My print sizes are not "standard" photograph sizes but either the short side OR the long side will fill the paper with a half inch margin. I also do my print checking at an 18 inch view distance. If it doesn’t pass that "test" the print gets trashed.
I even tried one 8 inch x 10 inch at 720 LPI just to see what happened. That didn’t give any noticeable difference either.
This is with 16 bit ProPhoto color space "12 meg pixel" files from a Fuji S2 with the Fuji File Converter EX.
Bill
Note that LPI and PPI are quite different measurements.
You obviously mean PPI here.
M
I used LPI as in the olde linotype lines per inch embedded in the file which the printer was printing at 2880×1440 DPI (dots/variable sized dropletts per inch here). I thought PPI was Pixels Per Inch on the monitor screen.
Looks like it is time for me to head back to www.scantips.com for a refresher course.
Bill
PPI is measure of pixel density at a given output size.
Indeed, images viewed full size onscreen have no ppi at all. "Physical" image size is only determined by the physical size of monitor and the screen rez being run ON that size monitor at the time.
An image will display same size on same monitor whether saved at 3, 300, or 3000 ppi.
M
Bill
Lines per inch refers to the resolution of a screen used on a halftone screen, and has no bearing on the resolution of a printer, which is dots per inch.
I used LPI as in the olde linotype lines per inch embedded in the file which the printer was printing at 2880×1440 DPI
The lines per inch are not usually embedded in the file
The relation between LPI and DPI is as follow for traditional halftone screens,
Apparent shades of grey = (DPI/LPI)squared + 1
Thus a 600 DPI laser printer outputing an image with a screen of 75 LPI will have 65 apparent shades (600/75=8 and 8*8 +1 =65) . Obviously you will want to have at least 256 shades, which is why imagesetters work at about 2400 DPI
I have not been able to find the equivalent formula for the stochastic screens used by inkjet printers
Rene,
Here’s a ready-reckoner for your above formula:
For any given printer dpi, as the linescreen frequency increases, the number of reproducible grey tones decreases. Here is a ready-reckoner:Screen
frequency (lpi) Output device resolution (dpi)
150 300 400 600 1200 2540
30 26 101 179 401 1601 7169
40 15 57 101 226 901 4033
50 10 37 65 145 577 2582
53 9 33 58 129 514 2298
60 7 26 45 101 401 1793
65 6 22 39 86 342 1528
85 4 13 23 51 200 894
105 3 9 16 34 132 586
120 3 7 12 26 101 449
130 2 6 10 22 86 383
150 2 5 8 17 65 288
200 2 3 5 10 37 162
220 1 3 4 8 31 134
300 1 2 3 5 17 73
Intermediate values can be obtained by using the following formula:
(dpi/lpi)^2 = No. of available tones.
This does not take into account dot gain, tone splatter, PostScript limitations etc.
If you have the LJ4 set to 300ppi and a default linescreen of 53lpi (plc mode) then you will only get 33 distinct tones, which is not enough for even shading. At 600 dpi that will increase to 129 tones which will be much better.
But for what is normally accepted as ‘continuous tone’ (256 tones) you would have to drop the linescreen down to less than 40 lpi which would give a very coarse screen
Thank you for the sudden crash course.
Bill, who slinks back into the corner & tries to digest the information
