FROM THE TUSTIN NEWS, THURSDAY, AUGUST 7, 2003


THE DOC IS IN...

Image resolution a mysterious quality

At a recent party I was designated the "official photographer" since I had my new digital camera with me.

The camera is a 4 megapixel Canon G-3 that came with a 32 megabyte Compact Flash image storage card. With this card the camera can store approximately 30 megabytes of images. Depending upon the selected resolution, the card can store anywhere from 7 to 196 images.

Image resolution is a mysterious quality. The higher the resolution the more detail in the finished picture. The lower the resolution the courser the picture quality. Since the camera allows me to set a number of resolutions, I had to make a decision about the final use of the pictures.

The Canon G-3 has five image resolution settings. One setting is the RAW format that converts, through computer software, into the TIFF format. TIFF images contain the entire range of picture information and give the highest quality images suitable for printing, publication or other uses. Unfortunately, this high resolution results in computer files of very large sizes. My Compact Flash card could only store seven of these images.

The other four resolution settings all convert the image in the camera into the jpeg (jpg) format. A jpeg image is a compressed format. It converts the image into a new form that results in smaller computer file sizes. However, this conversion loses some picture quality.

The G-3 has a selection of four different jpeg formats: 640 by 480 pixels; 1024 by 768; 1600 by 1200; and 2272 by 1704. The bigger the numbers, the greater the detail in the final picture. However, the bigger numbers result in larger file sizes so fewer images can be stored in the camera.

I decided that the final pictures undoubtedly would be shown on the computer screen, emailed to friends or possibly made into prints of less than 5 by 7 inches. Therefore I could use the lowest jpeg resolution of 640 by 480 pixels. At this setting, the 32 megabyte card could store 196 images in the camera. Of course, I could purchase a Compact Flash card of up to 256 megabytes to store more images. More about these later.

Incidentally, I decided to use the camera's optical viewfinder instead of the LCD viewing screen to give me more time before having to recharge the camera battery. This also solves the problem of daylight overcoming the image in the viewing screen.

Finally, I downloaded the images into my daughter's computer after installing Canon's camera software from a compact disk I brought with me.

Overall I was very satisfied with the final images. The Canon software lets them be viewed in slide show form which makes for fast, fun viewing. My only observation was that when viewed full screen, some of the pixels could be seen. This is called pixalation. Choosing a higher camera resolution can minimize this, but then you get fewer images.

On my home computer I have an image manipulating program that allows me to crop, resize and alter the original camera image. This is the process of converting the camera image into a final form. This important step will be discussed in later columns.

If you would like to hear more about digital imaging or other computer topics, visit "Coffee and Computers" at the Tustin Area Senior Center, 200 S. 'C' Street, any Friday morning starting at 9 a.m. Bring your questions or just come in and visit.

In the mean time, keep the neurons happy, synapses snapping and enjoy computing.

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Dr. Art Holub is a long time resident of Tustin and teaches computer and Internet courses at the Tustin Area Senior Center and the Tustin Adult School. Visit his web site at: www.arholub.com. This column is written to address the computer adventures and concerns of older adults. If you have comments, questions or suggestions for future columns, Email HIM at: doc@arholub.com.


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