FROM THE TUSTIN NEWS, THURSDAY, NOVEMBER 16, 2006


THE DOC IS IN...

Digital photography white balance

Last week I was taking pictures of some items that my wife had weaved. I used my digital camera and placed the items on a white background roll of paper and used flash as lighting. But every time I looked at the pictures on the computer the background came out sort of bluish-purple. What I had forgotten to do was set the “White Balance” in the camera to compensate for the flash lighting.

White balance probably is a term you have heard. Most cameras have a way to adjust white balance to compensate for various types of lighting situations. Let me explain.

The human eye and brain are marvelous devices. If I look at a person standing outside in bright sunlight and that person comes inside and sits under fluorescent lights, my eye sees the same color of their skin as when they were outdoors. My brain has “adapted” to the change in lighting. Unfortunately, electronic devices like digital or film cameras do not have this ability to adapt to changing lighting. In this example, under fluorescent lights, the digital or film camera sees the lighting change to greenish and the person’s skin color appears to change accordingly.

The “standard” white balance in photography corresponds to sunlight at noon. Pictures taken at any other time or under other lighting conditions must be compensated. In the days of film cameras, colored compensating filters were placed in front of the lens to make photographs look like they were taken under noon sunlight. We had filters for tungsten lights (ordinary light bulbs), fluorescent lights and various other lighting conditions. Even then, we would take a person’s picture in the beautiful reddish afternoon sun and have it come back from the processor looking like it was taken at noon. The processor adjusted his white balance for noon.

Unlike film cameras, digital cameras have internal ways to compensate for these various lighting conditions. This method of compensation is called “white balance.” Most cameras default to “automatic white balance,” a compromise that works most of the time. Again, if the white balance is incorrect, the images come out with a color cast that usually is undesirable. Then the camera can be set to custom control the white balance and compensate for outdoors, cloudy skies, tungsten or fluorescent lights, flash lighting and possibly other conditions. You have to read the manual for your particular camera to see how this works. The end result is that the pictures and their backgrounds come out looking “normal.”

If the image still is not to our liking there are other ways to compensate for lighting. In the above I have assumed we have our camera set to take pictures in JPG format. If however we set our camera to take the images in RAW, TIFF or BMP (this depends on your particular camera) the resulting image contains more information that can be used by various image manipulating programs. I use Adobe Photoshop Elements 4.0 and if I take the picture in RAW format, Elements allows me to make white balance adjustments to the computer image. This allows me to make fine adjustments to compensate for non-normal lighting conditions. This is what I did to get rid of the bluish-purple cast in my pictures.

This all may sound a little complicated but it just is another thing that digital photography has allowed us to do on our own computers.

If you would like to hear more about white balance 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. And visit my blog at drart.blogs.com.

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

I must add a sad note: This last week, Jack Swisher, a regular at ‘Coffee and Computers’ passed away. Jack was as nice a person as anyone could find and always had a smile for all of us. Our condolences to Betty, his wife of almost 60 years, and the rest of Jack’s family. He will be missed.
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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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