Detecting image forgery using linear constraints based on shading and shadows

According to the shadows and shading constraints in the Lambert illumination model, the paper proposes a method to detect image forgery. This method describes a multitude of constraints in shading and shadows based on the direction of the light source, by analyzing the intersection of the wedges to verify the images. The linear programming problem is employed to confine the direction and angle in the wedge, and the conjugate gradient methods are employed to describe the shading to verify the direction of the light source. The tampering image can be determined by the inconsistency in light source direction with shading and the intersection with wedges. Combining both the shading and shadow make the parameters in wedge more accurate. By the improved corresponding algorithms, the experimental results show that the light source direction and consistency can be calculated accurately in the shadows and shading.