**2. Processing and analyzing biomedical images**

For simplicity, image processing and analysis is discussed as an integrated methodology rather than separate steps or one being a subset of the other. Biomedical digital image processing generally implies using computers to manipulate digital image data pertaining to biomedical sciences to output other images possessing diagnostic information. Image analysis encompasses the entirety of steps used for quantitative assessment and abstract interpretation of biomedical images. Image processing and analysis includes a number of processes that adjust contrast and brightness, assist in distinguishing between different tissues, and others that perform measurements or assess the rate of development of certain processes.

Overall, the steps can be outlined as: image formation, visualization, enhancement, analysis, and interpretation. These steps and their order are not conclusive but suggestive as the specific order depends on the images being processed. For instance, different image enhancement techniques can be applied at different stages of image processing and analysis. For high-level analysis of automated systems, the appropriate steps are incorporated into algorithms with preset parameters for the target images. Such steps require a priori knowledge of the basic features and constitution of the images, and the algorithms typically cannot be directly transferred to other applications.

This chapter focuses on simple and commonly used methods for processing optical images such as for enhancing images prior to additional digital analysis and/or visual interpretation. The use of Excel in implementing the various image processing steps are demonstrated in the following sections. The general procedure used in Microsoft Excel for implementing these different image processing methods are outlined as follow: (1) creating a new (blank) output worksheet; (2) applying the method's formula to the upper left cell, i.e. A1, utilizing the original R, G, and B data; and (3) copying the formula to apply to the rest of the cells up to the extent of the original data. The original data is therefore preserved in the processing.
