IMAGING SYSTEM RESPONSE LINEARIZATION AND SHADING CORRECTION.

Shading correction of image sensors is an important operation in visual inspection applications. The generation and application of shading correction with and without imaging system response linearization is demonstrated. The linearization is achieved by subtracting the dark current image and by applying a look-up table. The content of the look-up table is obtained by fitting an analytical function to the measured system response. The linearization enables the shading correction to be a linear operation. The quality of the linearization and the shading correction is evaluated using statistical parameters of the processed images. The results show a substantial decrease in the standard deviation of the gray level distribution of uniform reference images. 4 refs.