Technical Specifications:

Click here for Step by Step Procedures for Scanning Film

Digitizing method

I. Scanning

Resolution: 20 microns (1270 dpi) or 1200 dpi
Dynamic Range: 8 or 16 bits
Scanner: Has to have transparency adapter

II. Using Adobe Photoshop 8.0

Because of the density of the analog positive film, images needed some recovering. The process used is shown below.



The histogram of the original image shows that most of the image curve is above few shades of gray. Once we spread the histogram we are spreading the image curve over larger area (more gray variations) and data on the image becomes more accessible to human eye.

III. Using MatLab 7.0

At this point in the process the image seems clear but there is still some "noise" in the image that make it seem like there is more information then there is. To remove this "noise" FFT (Fast Fourier Transform) is used. To do FFT you need low or high frequency pass filter depending on which one works better for the type of the image used. For Aircraft Radar data low frequency pass filter was used and one with radius < 0.5 worked the best on most of the sample imagery. Here is how it works:

The original image seems more detailed, but all those details are "noise" that is "false data"; it's not actually there. Even though for this example we used circular filter some images need to be filtered with non-symmetric filters.