Output Options; The DPI Myth; Optimal Settings For Printing Page 2
The key to re-sizing is to uncheck the "Resample Image" checkbox. For enlarging a print beyond what would be acceptable with a simple ppi change, Resample Image is the way to go. For really big enlargements use a program like Alien Skin Software's Blow Up (my current favorite for quality enlargements) or Genuine Fractals. In this case, I'm going to set a print size of 12x20 (#3). As you can see, with Resample Image checked, my pixel dimensions have changed from 1961x3244 to 2902x4800.
The final point of confusion for many is the quality options available in the printer driver. You'll usually find two or three quality settings which affect the density of ink placed on the page. This is one of those cases where more must be better right? Not always for you, but certainly for the printer manufacturer, since you'll be using more ink! And, you'll wait longer for your prints, too--as much as twice as long, all for minimal improvement in most cases.
I typically print at the normal setting, which if you use Epson is called "Best Photo," and on HP it's "Best." Canon is the exception here, and I always choose "1" as the quality setting. In almost every case, the print quality at these settings will be indistinguishable from the high quality setting. Again, with Canon I do see a visible difference between the "1" and "2" settings, and with a minimal difference in speed, so everything gets printed at the higher setting.
For final prints on gloss or luster media I will sometimes use the highest quality setting ("Photo RPM" for Epson, "Maximum DPI" for HP)--I don't find any benefit to these settings with most fine art papers though. These settings will trigger the higher density prints that generated those big numbers seen earlier, like 2400dpi.
A DPI/PPI Cheat Sheet
To help condense all of this down a bit, and hopefully give you a handy quick reference for printer settings, here's a list of commonly used settings. For images with finer details, and prints done on gloss or luster media, a higher setting will work best. And, the larger your source file, the better your results will be since there's less image resampling to be done to get a larger print.
PPI In Image Size Dialog
|8x10 and smaller||360 ppi (Epson) or 300 ppi (Canon & HP)|
|13x19||240 ppi (300 acceptable for larger images)|
Jon Canfield is a popular instructor and author of several books on digital imaging, including "Print Like a Pro" and "RAW 101." You can visit Canfield on the web at: www.joncanfield.com.