Thursday, June 24, 2010

White balance and file management.

This week we reviewed some great photos of the Riverwalk in Council Grove.  Unfortunately, it's tough to get a real good look with a projected image, I'll see if I can improve on that next week.

Color temperature is how photographers describe the color of the light affecting the scene they are trying to capture.  The eye and brain automatically adjust to changes in light, whether it be sunlight, florescent lights or those weird yellowish lights you find in gymnasiums.  Cameras can adjust and make a "guess" using a setting known as automatic white balance.  The AWB can be usually pretty accurate, but often is a bit off in sunlight and when shooting landscapes.  Color temperature can be frustrating to deal with. The more accurate you set your color temperature, the less you will have to fiddle with your pictures later on.  Your camera will have the following settings:  sunlight, tungsten, florescent, cloudy, flash, K (for Kelvin, you pick the number), AWB (auto white balance, not the band from the 70's), and two triangles with a box in between, which is custom white balance.

Custom white balance is very valuable. . .it is usually very accurate and really helps in making sure your colors are very close to correct without needing to make a lot of adjustments later.  Canon and Nikon cameras have a custom setting where you take a photograph of a white or neutral gray object, then the camera sets the color balance from that. Products such as Colorright, ExpoDisc, Balna discs are useful for this.  An article I read recently recommended using a Melletta coffee filter.

File Types and Work Flow

Digital SLR cameras can produce different types of files for use in transferring your photos for publishing, editing, or printing.  JPEG file formats are smaller in size.  They can have different levels of quality.  Lower quality files are smaller, but contain enough information to create good photographs for use in websites.  Higher quality files are better for editing and use in printing. 

When a JPEG file is created in the camera, the camera makes a set of decisions based on the settings in the camera, including color temperature, amount of sharpening, noise reduction, contrast and color balance.  You can search your menu settings in the camera to find these and adjust as necessary.

The RAW file is a file that contains the entire gamut of information collected by the sensor, given the amount of light provided to it.  A RAW file has to be read by a specific program designed to interpret and adjust RAW files.  Canon uses "Digital Photo Professional".  Nikon uses "Capture NX".  Other commonly used programs are Adobe Lightroom (my favorite), Adobe Photoshop, and Capture One.

When you move a file to the computer to evaluate it, adjust it and move it to it's final destination, this is commonly known as work flow.  RAW files are perfect for work flow, as so many adjustments can be made without degrading the quality or the details of the photo.  Steps involved in work flow are generally the following:

1.  Download to the computer
2.  Sort and rate
3.  Adjust the image
      a.  exposure
      b.  white balance
      c.  color balance
      d.  contrast
      e.  sharpening
      f.  noise reduction
4.  Save

Software such as Lightroom and Capture One are specifically designed to improve your work flow.  They are fairly expensive ($199 plus) but if you do a lot of photography, they are definitely worth it.  You can download the Adobe Lightroom program here.  Download the CaptureOne program here.  Each program has a 30 day free trial.

Also the class had a couple questions about color management.  It's pretty obvious to see that an LCD projector doesn't have the same color as a color monitor.  Also, monitors have different color profiles. . .pictures can look different on different monitors.  All this variability really messes with your brain after awhile.  If you look at a portrait on one monitor it may look wonderful, but on another, the skin tones may be too red or too blue.  Again, you can spend some money to solve this problem.  You can calibrate your monitor with a colorimeter, such as Spyder or ColorMunki .  

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