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Mocavo

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Tuesday, May 25, 2010

File formats for saving "original" photos -- Part Two

In my previous post on this subject, I covered some of my experiences with getting into digital cameras. The point of that discussion was that the file format used to store digital images depends on the availability of those formats both from the hardware (the camera or scanner) and the software. Before I can discuss this further, I need a few definitions. First of all are the terms lossless or lossy. A lossless image file is saved with a compression algorithm that does not discard information obtained from the camera. In contrast, a lossy algorithm allows image degradation (loss of information) to achieve a smaller file size.  Just for clarity, an "algorithm" is a programming term referring to a precise set of rules specifying how to solve a particular problem.

To put that into plain language, some types of image file formats preserve all of the original information from the camera and some trade off a smaller file size for a loss of some information. Now this concern about file size made sense when computers and storage devices (i.e. hard drives, flash drives etc.) were small and expensive. It takes a huge amount of storage to save all of the information from even one camera image, much less tens or hundreds or even thousands. However, I am going to focus on the present hardware and software issues, not those occuring even five years ago (or even one year ago). Computers have become much faster and storage has become almost incredibly inexpensive.

In a recent trip to Costco, I found two different manufacturers' hard drives on sale each with 2 Terabytes of storage for $129 each. On Amazon.com There are a number of 2 Terabyte drives in that same price range, for example, Seagate FreeAgent Desk 2 TB USB 2.0 Desktop External Hard Drive ST320005FDA2E1-RK (Silver). It is now possible to save tens of thousands of uncompressed images for a very reasonable cost. So the rationale in saving hard disk space by compressing data has essentially vanished.

One real issue with many computer users is the speed and size of the processor in their computer. Most of the newer external hard drives connect to the computer through a USB (Universal Serial Bus) connector. Older computers do not have USB connections. Today's faster computers are not just faster than their predecessors, they have multiple processors. This is like have 2 or 4 or more computers working on the same file at the same time. Presently, faster computers have two - 4-core processors giving a total of eight processors, that is like having eight computers working on the file at the same time. This analogy is not perfect, use of the processors depends entirely on the programs running on the computer. If the programs are not written to take advantage of the extra processors, then they will be ignored and the program will run as if it had a single processor.

So another issue is that the software must take advantage of the newer computers' multiple processors. If the program wasn't designed to take advantage of the faster computers then all of the power of the computer is essentially wasted. Most programs running on today's computers do not need multiple processors. However, if you are going to process a large number of photographs either by digitizing film photos or by downloading pictures from a digital camera, you may quickly exceed the capability of even recent computers. Programs like Adobe Photoshop CS5 are designed to take advantage of the faster machines and multiple processors and will run exceedingly slowly on older computers.

 So the main criteria, in today's world (like I said, not last year's world) is to save all of the information obtained from the camera. There is a file format which preserves all of the information from the camera in many cases and is referred to as "RAW" or "RAW data." A raw file is essentially all of the data that the camera's chip recorded with some additional information tagged on. But all RAW files are not created equally. You cannot expect to get the same quality image out of $100 point and shoot camera that you can expect from a high end Canon or Nikon. Additionally, all of the information captured by the camera doesn't mean much if the lens you are using is bad or dirty.

None of the other available image file formats preserve all of the camera information, although some of the formats are lossless, such as uncompressed TIFF files.  JPEG files are always lossy because they are compressed and in the compression process, lose some of the information present in the original image as it comes into the camera. Unfortunately, until recently few cameras even supported a RAW image format. Almost all of the cameras automatically output JPEG or TIFF images.

Since most people never adjust their photos at all, or do any photo editing, the file format is somewhat immaterial. However, if you consider your photos to be a valuable resource, you should seriously consider upgrading to a camera and software combination that will support RAW files.

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