Patent ID: 6909502

Claim:
A method for quantitatively measuring a level of ripple and distortion in a transparent sheet material, the method comprising: projecting projected image of the transparent sheet material onto a screen, digitally capturing digital image of at least a portion of the projected image and generating parameter signals from the digital image, wherein the parameter signals comprise σ v , σ pxp , f 1″ , and f 0.3″ wherein σ v represents a standard deviation for a defined area, σ pxp represents a standard deviation of a pixel-to-pixel difference over a full area of the digital image, f 1″ represents a summed contribution of wavelengths of about 1.7 inches to about 0.5 inches, and f 0.3″ represents a summed contribution of wavelengths of about 0.2 inches to about 0.5 inches; and quantitatively assigning a value to the level of ripple and distortion present in the transparent sheet material.