Photoshop Curves tool allows you to change the contrast inside a digital photography. If Levels offer only three areas of action, Curves get you more than middle tones and lights and we can use up to almost 16 intervals of luminosity.
Curves is in essence an equation able to translate the luminosity levels from the initial photo into the final photo.
Initially the luminosity level read by the original file is translated accurately in the resulted file and the translation “curve” is actually a straight line with a 45 degrees inclination.
Sometimes, because of the conditions in which the photo was taken the image does not have the contrast we desire.
The Curves tool allows us a smooth modification of contrast through changing the segments belonging to the entry value. We can choose a set of reference points that when modified will increase or decrease the contrast between two neighbor levels of luminosity depending on the curve’s slide.
An abrupt slide of the curve will produce a bigger contrast and a smoother slide would generate a smaller contrast.
With the help of the mouse we can create up to 16 reference points in the curve between X and Y axis. Through creating this reference points we can adjust the photo so that a certain luminosity value from the original photograph is increased or decreased.
The adjustment is done by pulling up or down the reference points. We can change the local contrast by curving the straight line in the graphic.