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Mocavo

Some people eat, sleep and chew gum, I do genealogy and write...

Tuesday, November 27, 2012

Comments on the equipment for digitizing images

In recent posts, I have talked about the challenges of handling huge numbers of digital images. In this post, I need to go back a little and talk about the physical process of scanning and the equipment needed for reaching archival levels of preservation. Most people associate the amount of money equipment costs directly with quality. However, quality can be independent of cost. Where the correlation between the cost of an item and its quality breaks down is frequently in the area of highly specialized products. The cost of specialized products is determined more by the demand, i.e. the number of potential users, rather than the quality of the product itself.

From another viewpoint, the cost of products can increase for any number of factors, while the actual quality of the product may not increase. Let me give an example. Are the most expensive cars in the world highly rated for their dependability? If I am traveling on city streets from my home to the Mesa FamilySearch Library, what would I gain if I were driving a $200,000 Lamborghini Gallardo over my $25,000 5 year old Prius? Why would I care if the Lamborghini could go from 0 to 60 in 3 seconds, when the top speed limit is 45 mph? Would the fact that currently the Toyota Prius C is rated the most dependable car of all by Consumer Reports influence your opinion?

I use this example to show that when you are looking to solve a particular problem, such as driving to work every day, you may need to look at the quality of the product more than other factors. But the real question is whether or not spending more actually increase the quality of what you are trying to produce? In cars, you may put more emphasis on style, utility, comfort, and many other factors. But when we are talking about producing a very specific product, such as archival quality digital images, we have far fewer considerations.

The goal in digitizing images is to produce a high quality image in an archival format and then preserve that image for the future. But once we have reached that goal, we can continue to spend more money and not achieve any more usable quality. In fact, in one area, the resolution of the image, we may exceed the physical ability of the human eye to distinguish the increased resolution. Fundamental to the whole process of digital preservation is the quality of the original document or photograph. Further, the requirements for preserving printed documents are far different than those needed to adequately reproduce photographic images. The final use of the image is also a factor. Is there a need to reproduce the image at a huge size? For example, for posters or billboards? Or is the information in the image what is important rather than the ultimate quality? For example, a copy of the page of a book.

Let me suggest two limiting factors for any digitization effort; for text material, the limit is readability, for photographic images or those with intricate detail, it is the physical limit of our eyes' ability to distinguish detail. Unless there is some other reason to be concerned with higher quality, once those limits have been reached, further "quality" i.e. resolution of the images adds no further value. There are of course, some rather large exceptions if the intended use, as I mentioned, requires reproduction at a larger physical size.

Today, we can use two basic methods of acquiring digital text and images; devices that fall into the category of scanners in a multitude of sizes, shapes and formats, and devices that fall into the category of cameras, also available in a huge selection of sizes, shapes and quality. The cost of both of these categories can vary from under $100 to hundreds of thousands of dollars. The basic question is what do I have to spend to obtain the necessary quality and what other factors do I need to consider?

One factor I have yet to mention with respect to digitization, is the time it takes the device to produce an image. From my own experience, the time it takes to do the digitization is by far more of a factor in completing the projects than the cost of the equipment. I have found that after digitizing hundreds and then thousands of images, the overall speed of the equipment increasingly becomes a factor.

It is also apparent, that acquiring a digitized image is only a small part of the process of preservation. You need a computer to process the digitized images and storage devices for storing and archiving the images. These further processes involve additional expense and considerable equipments. Additionally, you will need a physical space in which to conduct the digitization, meaning, you need a room or someplace to work.

In the end, the ultimate digitization product may depend more on your own preferences and resources than any other factors. You may be unwilling or unable to spend either the time or the money to gain additional quality and speed.

These comments will continue as I examine the level of quality and equipment needed to reach a level that could be considered digital preservation.


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