Imaging system response linearization and shading correction

Shading correction of image sensors is a very important operation in visual inspection applications. The generation and application of shading cor-rection with and without imaging system response linearization is discussed and demonstrated. The linearization is achieved by subtracting the dark current image and by applying a look-up table operation. 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.