Digital Photography

Image averaging works on the assumption that the noise in your image is truly random.  This way, random fluctuations above and below actual image data will gradually even out as one averages more and more images.  If you were to take two shots of a smooth gray patch, using the same camera settings and under identical conditions (temperature, lighting, etc.), then you would obtain images similar to those shown on the left.

he above plot represents luminance fluctuations along thin blue and red strips of pixels in the top and bottom images, respectively.  The dashed horizontal line represents the average, or what this plot look like if there were zero noise.  Note how each of the red and blue lines uniquely fluctuates above and below the dashed line.  If we were to take the pixel value at each location along this line, and average it with value for the pixel in the same location for the other image, then the luminance variation would be reduced as follows.

There are times when you want to present a dramatic statement with your photograph. Direct, bright light will produce many deep shadows on your subject that, if worked with, can create a very dramatic impression. In landscapes, deep shadows can create a sense of danger in cliffs and rocky areas. A chasm filled with the black of shadow produces an image of danger and mystery. Even a portrait can be done with harsh light. Work with the angle of the light, taking several poses. A face partially obscured in shadow can appear mysterious.

Softer lighting adds a dreamy quality to your photograph. Soft, natural light such as found in the early morning or early evening hours is ideal. We can not always choose these ideal times for our sessions, however, and must make do with what we have available. Indoors, you can use candles as a light source or drape a sheer scarf over your flash to produce this softer look. Outdoors, try waiting for an overcast day, if possible or place your subject in the shade and use fill flash.