To add to what Connie says, I am color-blind. While I perceive that I see color many folks have told me that I can get it pretty wrong.

?

The biggest example for birding occurred down in Madera Canyon when i was looking for the Flame-colored Tanager. After chasing him up and down the canyon he finally stopped in an Arizona Sycamore (yellowish-green leaves).? I could not see him at all while my wife and one other lady enjoyed great looks at him.? He then flew to a feeder.? I saw him fly in, saw him on the branch , put my binocs up and he disappeared.? Took the binocs down, re-found him, and looked again.? This time I was able to pick him out, although he blended in pretty well with more sycamore leaves .? To my eyes, he blended in.

?

Second example is with deer.? I have a hard time seeing Blacktail deer in the woods.? They blend in.? The SE Arizona Whitetail, which are a different color (to me) stand out even when all i spot is a lower leg in a mass of tree stems.?


Hal Michael
Olympia WA
360-459-4005 (H)
ucd880 at comcast.net

----- Original Message -----
From: "Connie Sidles" < constancesidles at gmail .com>
To: "Tweeters tweeters" <tweeters at u. washington . edu >
Sent: Wednesday, October 31, 2012 10:20:29 AM
Subject: [Tweeters] Plover problems

Hey tweets, I've been following the discussion about the golden-plover ID with great interest, partly because it is about how we humans perceive color. This is a big issue in science and technology and has been a big part of my professional life for many years. As a print production consultant with more than 30 years of printing and color separating experience, I would like to offer some things to consider when using color as a field mark in photos:


1. Every person perceives color slightly differently. What looks reddish to some might look yellowish to another. Furthermore, our color perception changes with age: older people tend to see more yellow. (If you'd like to check out how perceptive your eyes are to minor changes in tone, take the color test at? http :// www . xrite .com/custom_page. aspx ? pageid =77& lang =en ?and see how well you score.)


2. Every computer monitor displays color slightly differently, unless the monitors have been color-calibrated to the same standard. Color-calibrating a monitor is a complicated technical process (magazines that desire to color-calibrate their entire production system have been known to pay an expert as much as $10,000.00 for this service). As a result, what looks yellowish on one monitor can look bluish on another.


3. Monitors display color using discrete pixels of emitted light. The pixels are created (on my liquid crystal screen at least) by dyes that show RGB light. The dyes are limited in their gamut (range of colors). The gamut emitted by a computer screen is also limited by the amount of back light it uses. Screens can be set to be very bright or not so bright, changing the colors they display. Nature displays color by absorbing some wavelengths of light and reflecting others. Colors in nature can only be seen in sunlight, whereas colors on a monitor can be seen when it's dark. Because of these limitations and differences, a monitor's colors are not a perfect match for nature's colors. (If you want to read more about color gamut, check out the Wikipedia article "Gamut" and references in it.)


4. Different software apps address Problem #3 differently. You can see this for yourself if you take the same photo and open it in: PhotoShop , Adobe Reader, iPhoto , Adobe Acrobat, and Preview. The photo looks slightly different in each app.


5. I don't know very much about digital cameras, but I suspect that they must make compromises between the natural spectrum and the color gamut, just as monitors must.


6. Since the colors we see are wavelengths of light, they can vary depending on the angle at which they arrive to shine upon an object and also the angle at which they leave an object to reach our eyes or a camera. Ambient light also depends on how the surroundings reflect or scatter light.?Ambient light is thus very changeable, making it difficult to compare one photo to another when the photos are taken at different times and under different conditions.


7. Midtone colors (ones made up of almost-equal amounts of red/green/blue light) are especially sensitive to factors 2-6 because slight differences in any one of the RGB components can sway the midtone disproportionately toward R or G or B, making the overall tone change significantly. Browns are midtone colors.


8. The human eye is deeply influenced by ambience , seeing colors that either aren't there at all, or are different than we perceive. To see how this works, check out the TED lecture on YouTube : Don't Believe Your Lying Eyes.?


The conclusion I reach from all the above is that we should be very careful about using colors as definitive field marks when differences between one species and another are slight, when there is overlap among individual birds, and when you are trying to identify a bird in isolation from other members of the same species or other members of related species. - Connie, Seattle


constancesidles at gmail .com
www . constancypress .com







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