DEFOCUS CORRECTION USING STRUCTURED ILLUMINATION

Local visibility is used to identify areas of correct focusing in stac ks of digital images of scenes illuminated with structured light with progressive severe defocusing. Visibility is a maximum when focusing i s correct. The method requires high spatial frequency for best perform ance. So, the scene is projected with a set of high contrast fringes a nd we use the spatial derivative of the images that compose the stack, to Increase its relative content. An image with partially corrected d efocusing can be constructed in this way. A formalism was developed fo r evaluating the visibility behavior with sinusoidal input as a functi on of the defocus distance. The visibility peak is the highest when th e spatial derivative of the double defocused sinusoidal intensity is u sed.