A few scanning tips


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On the left below is the same original 400 dpi scan of the color print, and on the right is a 1950 dpi scan of the negative on a 30 bit Microtek 35t Plus film scanner.

Both images have had the same sharpening treatment. Nothing is faked. There is a considerable difference in the detail achieved in the same size image. Remember, we're 30 feet away with a 50 mm lens, and this is 3.4% of the total film area.

That these two are far from equal is the best proof that prints cannot deliver expected detail over 300 dpi. Film is better.

400 dpi 1950 dpi

Megabytes are very desirable when printing large images.

New Section

The images above were done several years ago. Below are newer scans of the same negative with a Minolta Scan Dual II film scanner at 2820 dpi, and with a Polaroid SprintScan 4000 at 4000 dpi. This is a cropped area of film, 0.13 x 0.23 inches (smaller than a pencil eraser).

The 2820 dpi scan created a 30 MB 3912x2632 pixel image. The full frame image would scale to print nicely on A3 or 11x17 inch paper at 240 dpi.

This video screen image is nearly half again larger than the others just above, so it's hard to compare precisely, but the point should be clear: The print simply cannot begin to do this. The green fern alone makes it clear that scanning film is better, especially when you have to go above 300 dpi scanning photo prints. The color balance is a little different, better I think, but it wasn't a concern here.

2820 dpi

1/3 size

Below is a scan of the same negative with a Polaroid SprintScan 4000 dpi film scanner, at 4000 dpi, using Polarcolor Insight 4.5.1. The full frame image was 60 MB 5500x3772 pixels. The full frame image would scale to print at 22x16 inches on paper at 240 dpi. This portion would appear approximately 1/3 size on paper if printed that size (simulated by resampling at right). The large cropped JPG image is heavily compressed here to 7% size, but it is still 99 KB.

4000 dpi

Copyright © 1997-2010 by Wayne Fulton - All rights are reserved.

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