It works by redefining the sharpest color and contrast areas in an image. The combination of Unsharp Mask and Sharpen Edge can restore a severely resized image to readibility. Color Adjustments Photographs taken using fluorescent lights, sunset or sunrise, candles, campfires or hearth fires can all have a very strong color tint. The tint can range from green to red. Color Adjustments are features of image editing software which allow you to shift the color balance of an image back to a more normal color.
Some programs have automatic color balalncing controls.
Beyond Basic Edits Image editing software from the most expensive to the least expensive all contain filters and special effects which can be used to enhance or sharpen any image or photograph. In order to fully appreciate the features of image editing software you should read the manual and practice using some of the filters. Use photographs or images which appear ordinary and experiment to see if some of the filters allow you to change an ordinary image into one which has more visual impact.