BetterPhoto Q&A
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Reproducing Pictures and Printing Digitally

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April 27, 2001

It depends on how you define "high quality." My standards are high; very, very high. I'm accustomed to the work pro labs can do and results possible from the finest grained medium format films on pro papers. I'm also accustomed to high archival life; for prints it means being able to hang them on walls for decades without noticeable color shift or fading. What follows is my opinion about the absolute minimum of what's required technically for "high quality."

It is possible to get "high quality" reproduction at considerable cost if you limit size to about 8x10 maximum. First, you need very high resolution scanning capability. Then you need the printing capability. According to what I've read the current technology for archival longevity is the dye sublimation process.

Working backwards from the print, that should be done at no less than 300 dpi with a minimum of 24-bit color requiring a final digital file for an 8x10 of 2400x3000 pixels at 24-bit color information. (I would want 600 dpi printing for this size using a 4800x6000 pixel file). The scan should be at least twice this resolution so it can be appropriately sharpened using an "unsharp mask" technique to restore sharpness lost during optical scanning. This means a scan that contains 4800x6000 pixels at 24-bit for an 8x10. This is _optical_ resolving power, not interpolated. Resize required scanning and file sizes for smaller prints, but don't drop back on the 24-bit color.

In addition, the scanner must have a high "dMax" for contrast and high end optics to prevent aberration or distortion. I've encountered distortion with less expensive flat-bed's used for scanning prints and it's a royal pain to correct . . . with some loss of resolution in the process. The best scanning is done from the film using film scanners, not prints, so do it from the film if at all possible.

Now start figuring the cost of this with high end scanning and printers specifically made for dye sublimation. My conclusion is it's still less expensive to get hundreds of large prints (8x10 to 10x15) or thousands of smaller ones (4x6's) done by a pro lab than buy the capability to do it as well as they can.

-- John

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April 29, 2001