September 13, 2009
When performing a microfilm scan, there are many issues that need to be considered to assure that the resulting quality is the best possible scan.
To start, you need to determine how much information you want to capture from the film. At first, this may seem to many like a dumb question, thinking that the more the better. In many instances that is the case, but there is a limit to this benefit and at one point there is a cost to pay that counteracts some of the benefit.
The two question to answer before starting the microfilm conversion process with respect to ultimate quality are Film Scan Resolution and File Type.
The film scan resolution is often refer to as DPI or “dots per inch”. The DPI is important because it determines the size of the dots or points that make up an image. If you look at a one inch by one inch square of an image and zoom in on it so that you could see the dots that make an image, you would be able to see rows of dots that change color. A resolution of 100 would have 100 dots going across the one inch. A 300 DPI image would have 300 dots in this same row. To fit more dots in the same distance, they would have to be smaller and more compact. More dots means that the image would have better chances of been higher quality.
More dots also means that there is more information. More information also means that the image is bigger in terms of file size. This is the down side to a higher DPI. End users are sometimes affected by this issue for a couple of reasons. One is the hard drive space that will be needed to store the images. If the project is large, the difference in drive space may be significant. The second issue has to do with the end users system and its ability to handle the images quickly. The larger the files are, the more information the system needs to process. If going with larger DPI, the end user needs to make sure that the operating system, the processor in the computer, the network, and all other components, are ready to deal with the larger images and can achieve the desired results.
In addition to the DPI scan resolution, determining the file type is also important. There are various image types, including gray scale, j-peg, tiff, and others, and some various compression types withing these selections. Grey scale images offer the possibility of generating very high quality images with lots of details but it is usually much higher in file size.