 Curves tool in Photoshop is perhaps the most powerful and flexible image transformation. Since photographers effectively paint with light (read article about Technique  for Light Painting Photography).
Curves tool in Photoshop is perhaps the most powerful and flexible image transformation. Since photographers effectively paint with light (read article about Technique  for Light Painting Photography).They use curves to practice because it affects light's two primary influences: tones and contrast. Tonal curves are also what give different film types their unique character, so understanding how they work allows one to mimic any film — without ever having to retake the photograph.
Below is step by step video tutorial for Simple Color Curve in Photoshop.
 



 
 
 
 
 






 
