Approximate pixel dimensions. Not necessarily a measure of quality. (eg. Enlarging a 12 MP image from a good camera (sensor) may yield a better image than a 44 MP image from a cell phone).

Mega Pixels (MP)	Pixels	inches (at 300 DPI)
1.6	1536 x 1024	5.1 x 3.4
3.1	2048 x 1536	6.8 x 5.1
6.3	3072 x 2048	10.2 x 6.8
8.2	3504 x 2336	11.7 x 7.8
11	4604 x 2704	15 x 9
22	6144 x 4069	20.5 x 13.5

White balance

• Light has color! If you illuminate an white object with light that has color, it will not be white. Our brain interprets it as white. Cameras do not have brains.
  
  
• A white sheet of paper under
  • Florecent light will register as greenish blue (turn off florecent light whenever possible!)
  • Tungsten bulb will register with a reddish cast
  • Sunlight varies during the day. (sunset: golden red, midday shadow: blue tint)
  
  
  
  
  
  
  
  
• Balance of colors in light is measured as color temperature on the Kelvin scale.
  
  

  11,000K	Skylight (w/o direct sun)	Blue-ish light
  6,000K	Strobe
  5,500K	Daylight Film
  5,000K	Daylight
  4,000K	Flash bulb
  	Late afternoon, early morning light
  3,200K	Flood lamp, Tungsten
  2,000 K	Household bulb
  1,900K	Candle light	Reddish light

• If you are not shooting RAW need to specify what lighting condition you shot your images in on the digital camera
• choose the right film (tugsten, daylight)
• use filters and correct color cast

RAW == Undeveloped film. Uncooked steak. JPEG, TIFF == Developed image (hopefully in the right way). Cooked steak.

• The camera interprets, shapens, color corrects (white balances), anti-aliases, applies noise reduction...etc.
• remember how destructive these operation in Photoshop were?

in RAW, you get to make the decision on a image by image basis, after the fact.

• RAW file = raw data from the sensor in camera
• not a file format in of itself. (Nikon uses NEF format, which is a RAW file)

You cannot change the amount of light that was exposed. If you underexposed your photograph, that is what you have to work with.