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Even Photos Get The Blues....Why your photos look blue and how to fix themPosted on Wednesday, April 11, 2007 at 10:38 AM - Post CommentEVEN PHOTOS GET THE BLUES Why some of your photos look blue and how to fix them THE PROBLEM I did a casual search on the web for photos of gulls and terns and quickly came up a few shots that illustrate the problem this article addresses: photos with a bad blue shift. I could have searched for any species, really. Blue-shift-“polluted” photos are everywhere. And when people show me photos for comment, color shift is the number one problem I see.
THE CAUSE(S) Put a pencil in a fishbowl and you’ll see the pencil bend. That’s because as light travels from one medium (air) to another (water or glass) the speed changes and the light bends. The light bringing your eyes the image of the pencil under water has bent in relation to the light from the pencil above the water.
Put light through a prism and you’ll see that not only does light bend, but the colors that make up light can bend differing amounts. And the frequency with the shortest wavelength (blue…) bends the most.
Now consider what is happening when you attach a camera, with several glass lens elements, to a telescope, which has its own lens elements. Basically, you have a recipe for a blue disaster. And that’s often what you get. There are some other possible culprits, as well, especially when you use a less expensive “point and shoot” camera for your digiscoping (the only kind that will work with most scopes…). Some digital cameras have “micro lenses” that concentrate the light right above the sensors and can contribute to the color shift. Also, when a sensor becomes saturated, it can “bloom” into adjacent sensors, causing the color aberration to spread. Even without a scope attached, cameras can induce a color shift and in addition to blue shifts, and I’ve seen red shifts from some very popular cameras in outdoor light. HOW BAD IS THE PROBLEM IN YOUR PHOTOS? Color shift usually takes one of two forms: fringing, and an overall color shift. A color fringe or “blooming” problem leaves you with blue or purple outlines around dark objects that are backlit. It’s usually easy to tell if you have a fringing problem. As you can see from this picture of a pair of Barred Owlets I took in To see a blue-fringing problem clearly, open your photo in Photoshop. (In subsequent columns I’ll go over Photoshop and its features in detail. For this article I’m going to describe the steps to take to solve the color shifts without getting into any Photoshop overview of theory. I’ll highlight Photoshop commands in red.)
Find some point of high contrast, such as the branch against the sky in the owl picture. Zoom in and take a look at a small section including both the darker object and the sky. Pixels within the color fringe problem area will be from blue to purple, with some lighter and some darker blue than others. Fringing is usually very easy to pick up by just looking at the photo. An overall color shift can be a lot more subtle, but really is often more damaging to your photo as it has affected all parts of the picture. Here is an example of a subtle overall color shift in this photo of a Lemur I took in fairly good light in
FINDING YOUR BLUE-SHIFT PROBLEMS Photoshop offers some tools for helping you find your color problems. For a color fringe problem, zooming in is usually all you need to do to find the problem. To quickly Zoom In in Photoshop, hold CTR (CMD) + the SPACE BAR and drag over the area you want expanded. A useful indicator of any color shift is the INFO window.
If you don’t see the INFO WINDOW in the upper RH corner of your Photoshop window, go to WINDOW > WORKSPACE > DEFAULT WORKSPACE and it will pop up under the Navigator pane. As you move your cursor around your photo, the INFO window shows you the amount of R(red), G(green), and B(blue) colors in each pixel. Black is the absence of all colors. So a pure black area in your photo would show 0,0,0 for the R,G,B values per black pixel (more on pixels and colors in a future article). White contains the maximum amount possible for each RGB value. In a typical camera, which uses 8 bits of data to capture each color, the value for R, G and B will be 256 for each parameter. True gray is somewhere between black and white, with all colors in equal amounts. So a medium gray would show up as 128, 128, 128 (128 for R, 128 for G, 128 for B) in the INFO window. A darker gray would be 66, 66, 66 (66 for R, 66 for G, 66 for B) in the INFO window. (Double Devils….but I thought the devil’s color was red…??) If you place your cursor in an area that should be some shade of gray, somewhere from almost white to almost black, you can see how the colors are really balanced. A photo with a blue shift will show a higher B number than the R and G numbers. Be careful of testing an area that is “blown out” or completely white. If the photo has been over exposed, then all of the numbers will be 256 and won’t show what the actual balance was before they all got “blown out”. On this gull photo, notice that the values for the + cursor location on the wing are R: 173 G 190 B 233. If this area is really supposed to be gray, then there is definitely a blue shift in the photo. Here’s a gull shot that is more accurate. You can see that the gray area has much more balanced RGB values of R 161, G 158, B 149.
Besides using the Info Window you can also put a sheet of white paper next to your printed photo, or a white square in Photoshop and move it around to different sections. This can help you see subtle color shifts. Once you become sensitive to blue shifts, you’ll see them everywhere….an annoying point of view, unfortunately, in this all too blue world… THE FIXES There are different ways to fix a color shift in Photoshop. I’ll cover two techniques in this article. In later articles I’ll cover a few more ways, such as using the cloning stamp for wide fringing prolems, or other color replacement tools that Photoshop offers. Fixing a Color Fringe Open your photo in Photoshop Create a or choose IMAGE > ADJUSTMENTS > HUE/SATURATION In the top EDIT drop down menu for Hue/Saturation, choose BLUES After you choose “BLUE” your cursor will turn into an eye dropper. Use the dropper to sample the actual color of the fringe by just clicking the cursor in a blue area. It helps to blow up the image before you start this process (CTRL(CMD) + SPACE and drag) You can add colors to your selection by holding SHIFT and clicking on additional blue or purple pixels. Try and include all of the shades of blue you find as part of the fringing areas.
Once you have sampled the offending blue color range, use the Lightness and Saturation parameters to control the blue fringing. This usually works very well unless the fringe is very wide.
Just that simple adjustment made a huge different in this Owl photo!
Fixing Color Shifts You can use the same technique for color shifts. However it is usually easier and faster to use the CURVES tool. Open up a photo with a blue color shift problem. Choose IMAGE > ADJUSTMENTS > CURVES Choose BLUE from the CHANNEL drop down menu at the top.
 Pull down the line in the center of the curves box slowly and watch the effect. You can compare your effect with the original by checking and unchecking PREVIEW. You can also watch the INFO box as you make your changes, with the cursor in some bluish area. INFO will show you the original numbers as well as the numbers changed by the Curves tool.
When you fix your photo, you may see a huge difference. But if the color shift was subtle, you will more likely just feel that the photo looks more natural or warm. When you A/B the original with the fixed version, most likely you’ll be amazed that you were willing to accept the blue version at all! Of course curing the blues may wreak havoc on your song writing…..but your photos will sure look better! BY THE WAY, HOW ARE YOUR BINOCS? Don’t do this experiment unless you’re willing to face the truth…. I once picked up someone’s binocs on a birding trip and made the mistake of exclaiming “Wow, what a blue shift!” I then had to explain what a blue shift was, show it to her, and then watch her get a little depressed with the thought she was going to have to live with a problem she had never noticed it before. Bad deal... But if you’re up to finding out how your binocs are doing, point them at a dark tree trunk that is well backlit. Slowly move your binocs from side to side. If it’s there, you’ll see it….. Colors passing through Fluorite don’t bend nearly as extremely as colors do when they pass through plain old glass. So Fluorite is used for high quality camera lenses, binocs and telescopes. There are other processes that are also used with high end optics to fight the chromatic aberration that causes blue/purple fringing. For a more “high stakes” game, you can check your scope out the same way…. FORUM BUSTER OK, I’ve been asking you to mess with your photos…..changing nature….fixing them up to make them pretty. Has the integrity of your image now gone commercial? Are you destroying the purity of your original photo even by opening it up in Photoshop? I have heard people comment that they would never touch their photos in any program, because they want them to be “true” to the original bird. But are photos ever true to nature? Couldn’t edited photos be even more “real” than the original?? SEND ME YOUR IDEAS AND SUGGESTIONS This is a column, not a forum, and unfortunately I’m not going to be able to directly answer most emails. However, if you have specific questions about something that was covered in a column, please do send me a note. If something that I covered needs further explanation, I’ll try and provide that in a future column. I will also welcome and consider any suggestions for topics that might be of interest to the general birding community, especially areas of technology that you might like to explore, but feel you may need more information or some “how-tos” to get started. I’ll do my best to cover as many of these topics as possible. Send your comments, suggestions and (kind) thoughts to © 2007 Tom Stephenson |
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