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Your digital camera and its format options

When George Eastman popularized photography with the introduction of the Kodak, the ad read: “You press the button, and we do the rest”. The Kodak Brownie instructions read: “Stand subject in sun, with the sun behind the camera”.

We have come a long way since then; witness the instruction manual, the options and menus of today’s typical digital camera. This series of articles will attempt to lessen the mystery and, hopefully, reduce the anxiety.

To examine just one of the many options-why are there different file formats? My camera has RAW, JPEG and TIFF, and within the JPEG option many sub-options. How does one choose?



Back to basics. If you type a plain text letter in your computer each letter of the alphabet is stored as a byte. If your letter consists of a thousand characters (counting spaces and punctuation) then the file size is a little over 1,000 bytes, or a Kilobyte.

A digital photograph is stored as a bunch of closely spaced colored dots called pixels, short for picture elements. Each pixel uses three bytes to reproduce all the colors of the rainbow. If you took a photograph with a five megapixel (five million pixels) camera, then the file size would be 15 (5 X 3) megabytes. Fifteen million bytes is a large number, so large in fact that 15 megabyte files can quickly fill your camera card.




Back in the late eighties and early nineties when digital photography was in its infancy, a group of knowledgeable engineers got together and agreed upon a compression scheme-a method of reducing the number of pixels required for a digital photograph by about a factor of 10. This group, the “Joint Photographic Expert Group”, agreed on a standard that we know today as JPEG.. It is the most popular file format because one can reduce the memory required to store a photograph to about one megabyte.

The number 10 that I used in the above example is not fixed. The actual compression largely depends on the JPEG options you choose – basically a compromise between the file size and quality.

Let’s say you’re on vacation armed with your digital camera. You’re happily snapping away “knowing” that you will select the best pictures and send them to friends as e-mail attachments, or upload them to a web picture-sharing site. The point is that the pictures will be viewed on computer monitors where the size (as measured in pixels) is small, and low quality is not apparent. So you set the JPEG options accordingly: Size to Small and JPEG Compression to Normal. Thus, you’re able to record a lot of pictures on the camera’s memory chip.

Now you’re older and wiser and vacationing again the next year, but this time with a new DSLR (Digital Single Lens Reflex) camera and your objectives have changed-it’s all about photo quality. The pictures of the previous year did not print well, certainly not well enough to frame and hang on the wall. You’ve decided you will need at least three times as many pixels with minimal compression. Thankfully, memory chips have fallen in price and you’re able to set the JPEG options: Size to Large and Quality to Superfine. (Your camera’s nomenclature may be different of course.)

Now your photos have lots of pixels, which you can choose to keep if you want to print a high quality photo or throwaway some pixels if you decide to email the photos to a friend. You do need to downsize the number of pixels so the photo won’t take so long to send. There are many computer graphics programs available to do just that, and some e-mail programs have a downsizing option as well.

Professional photographers prefer the RAW format. By opening the RAW formatted photo in a computer graphics program like Photoshop, all the original pixels become available giving the photographer more editing options than are possible with JPEG.

I don’t use RAW. The highest quality JPEG setting results in pictures that, to me at least, are excellent. You can experiment to see if you agree.

Mitch Bain is a Volunteer with the Gold Country Computer Learning Center. Our website is http://www.gcclc.org. For information about computer classes call 273-0497


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