Manufacturing Information Solutions

[mistux]

Q: I am starting to scan my slides for printing purposes. The prints I intend to make will be no larger than 8 x 10. I have a HP photo smart S20 scanner, and hp 940c printer. At what resolution should I scan my slides, and in what format should I save them for printing? I have Photoshop Elements, and Photo Suite image editing programs.

Thanks
Jay

A: Most PC photo quality printers produce their best images at an output resolution of 300 ppi (pixels per inch). Not to be confused with the printers resolution of either 1440 or 2880 dpi (dots per inch). The latter refers to the fact that more than one ink droplet or dot is used to represent each pixel - yielding smoother, more evenly toned images.

That said, if your target image resolution is 300 ppi for an 8x10 image, the math says that your target resolution would be 2400 x 3000 pixels. But like many things in the digital world that number is not absolute. I would recommend scanning and printing several images at both 2400x3000 and at half that resolution. Compare the prints and see if the difference is visible with the naked eye. If not, you might consider the lower resolution to save on disk space and scan times - it's your call.

As for the best storage format, the two most widely used formats are TIFF and JPEG. The tradeoff here is that TIFF is the most accurate because it does the least amount of image compression. However that means that TIFF files are much larger than corresponding JPEG files. Another drawback with JPEG files is that every time you change and save a JPEG file it is compressed all over again - meaning that every time you save the file you lose a little more data, and pick up a little more noise. However, this problem has been overstated in many places and is far more noticeable with small low resolution files than with files in the range you're looking at.
http://www.vividlight.com/articles/1108.htm