Precise subpixel position measurement with linear interpolation of CMOS sensor image data

In the industrial automation it is often required to provide high precision measurements of objects positions and sizes. As a reasonable contactless method measurement based on digital image processing is used. In praxis the image-based measurement of physical quantities can replace expensive mechanical sensors. From the construction point of view it is reasonable to use CMOS image sensor for camera construction. The basic drawback of these sensors is not homogenous pixel photosensitivity distribution. This feature is especially crucial when sub-pixel measurement resolution required. Linear interpolation as one of possible methods results estimation on CMOS image data is discussed in this paper. Having realized a real-world experiment with a precise micro-positioning unit the practical results of measurement are presented and limitations of method discussed.