Wednesday, January 31, 2007
June 2004 HelpLine
* Disappearing Photos
* IRIS In Digial Cameras
* Acronym Acrimony
Q) I'm in the process of scanning my 35mm slides, negatives and various prints for which I have no negatives. Ultimately, I want to burn them onto CDs. I'm using the highest resolution that my scanner allows for the type of medium I'm scanning; with the negatives and slides, it's 2400 dpi; with prints, it's 300 dpi. Since I don't expect to print any of them larger than letter size, should I leave the files at their present size or resize them to letter size at 300 dpi before burning them to CDs?
A) First, let's deal with resizing your image before writing it to CD. If you do so, you may add artifacts to the image during the resizing process (if you simply change resolution, pixels don't change; however, if an image is sized up or down so that pixels are increased or decreased, artifacts can cause problems). Once written to CD, these artifacts are permanent even if you scale the image back down to its original size. This applies to digital camera images as well as scanned photos.
I recommend that you resize the image just before printing. At print time, then resize the image for a specific print size based on the original image file. As advances in picture processing continue, there's also the possibility that in the future there may be better algorithms for interpolation of pixels during the resizing process that won't harm the image as much.
If you're scanning small images, say, old 3x4-inch prints, and think you might like a larger size, you need to scan them at a higher resolution than 300 dpi. I'm not sure you'd be happy with them scanned at 300 dpi, then blown up to 8x10. You could increase the size—say, 4x6—by resizing to 200 dpi or go even bigger by printing at 150 dpi, and you'd still get good results. However, by simply scanning at 600 dpi or higher from the start, you'll have more printing options in the future.
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