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Blue Pictures

August 10 , 2012 12:04 AM
 
Blue Picture
 
During our Photography Class I was asked why some pictures looked ‘blue'. So, we loaded the pictures on my laptop and compared the EXIF information of two pictures and noticed that the shutter speed and F-Stop were the same. The only difference in the exposure was 1/3 on the ISO setting due to the camera set to ‘auto ISO'.
 
However, there was an unintended oversight due in part to the screen size of my laptop and the quality of the TV screen showing the pictures during class. Once I got home and loaded the pictures on my computer with a calibrated monitor the blue tint on the pictures was more noticeable and making it obvious that the 1/3 stop was not cause of blue pictures.
 

So, how do we ensure our colors are true?

 
There are three main concepts to understand how digital cameras capture and reproduce color: Light Temperature, White Balance and Calibration.
 

Everybody knows that pictures taken in the morning or in the afternoon look better (mostly) than pictures taken when the sun is high in the sky. However, not that many people notice the difference between fluorescent and tungsten lights, or ‘hot lights' and flash and that is mainly because our brain automatically compensates for the difference. For example, at a wedding, we will always see the bride's gown as white regardless of the light bulbs or candles because our brain already knows the bride is wearing a white gown. The camera, on the other hand, does not forgive and will capture a smiling bride wearing a yellowish gown.

If we are location or wedding photographers and we shoot using existing ambient light we need to understand light temperature in order to capture realistic colors and yet that is not enough.

 
 
Happy Bride
 
Whether we have always shot Digital or we transitioned from Film, White Balance is exclusive to the digital realm of photography. Understanding the relationship between Light Temperature and White Balance will allow us to capture a beautiful bride wearing a white gown and a handsome groom wearing a black Tux regardless of the light inside the church or at the reception. Now, someone might say that "in Photoshop we can set the white and black point to match the dress and the tux" and that might work... Unless the groom is a Marine who is wearing his 'Blues' and you don't want to show his Dress Uniform as black :)
We can also set a custom white balance to shoot the couple at high noon and give it a ‘sunset' feel. Most cameras perform well set to Auto White Balance but for those tricky situations we need to set the white balance manually or even set a custom white balance. Want to see the difference? Go outside, set your white balance to Auto and take a picture of your backyard or parking lot and make sure to include plenty of sky. Now, set the white balance to tungsten and snap the same picture again. Compare both pictures. Which picture has the more intense ‘blue sky'? Because of the Tungsten white balance the second picture will have a bluish tone which is 'cool' as opposed to 'warm' (just like the picture shown here taken over Southlake and White Balance set to Tungsten)
 
Nevertheless, even if we understand Light Temperature and have set our White Balance Properly we can still mess up a whole wedding photo album. The pictures look great but when we get the proofs they are either too bright, too dark or skin tones are off (white skin too white or brown skin too dark). How is that possible?

Well, our ‘blue' pictures mentioned above looked a bit dark on the TV and on my laptop they seemed to be underexposed. However, my monitor at home showed their true color. That is because the TV could not display as many colors as my laptop, my laptop had a higher contrast but my monitor at home was actually calibrated. Think about calibration next time you are in front of a dozen TV's at the store showing the same movie and you will notice that not all of them show the same colors. Another simple test is to look at the same picture in two or three different monitors or more if you have them and you will notice the same picture displays different on each monitor because each has a different profile

 
Another point to consider also is the gamma value used. Windows by default uses a 2.2 value (darker) while Macintosh has a 1.80 default value (lighter) and this means you could get a brighter print from a Windows machine and a Darker print from a Macintosh. A good idea is to either inquire your lab what profile settings they use for their printers or request them not to color correct your pictures. I prefer the latter so I can get consistent print results across multiple labs and regardless or who prints my pictures
 
In conclusion, we have to be mindful of the light temperature and set our white balance appropriately when we take the picture and make sure our monitors and printers are all calibrated accordingly. As a student explained back "garbage in, garbage out”
 
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