Image Calibration, Filtering, and Processing

Abstract

In this chapter we discussed image calibration, filtering, and processing techniques, which are used to prepare an image for subsequent data extraction and analysis. Size measurements from a digital image are calibrated by imaging objects with a known size. Pixel intensity is a measure for the composition of the imaged object and can be calibrated by imaging objects with known composition. Methods depend on the type of material and imaging technique. We discuss colour calibration, as colour is one of the most widely used types of data in image analysis. Filtering is performed on an image to remove artefacts that are unrelated to the object of study. The challenge is to find the best filter, one that removes all noise with minimum change to the actual information in the image. Described are techniques to remove the effects caused by uneven illumination during imaging, and methods to filter camera related noise. Image processing involves modification and/or enhancement of the image in such a way that the required numerical data can be extracted more easily. Processing techniques that are outlined include edge detection, segmentation, and processing of binary images.