Biomedical image processing is a very broad field; it covers biomedical signal gathering, image forming, picture processing, and image display to medical diagnosis based on features extracted from images. This article reviews this topic in both its fundamentals and applications. In its fundamentals, some basic image processing techniques including outlining, deblurring, noise cleaning, filtering, search, classical analysis and texture analysis have been reviewed together with examples. The state-of-the-art image processing systems have been introduced and discussed in two categories: general purpose image processing systems and image analyzers. In order for these systems to be effective for biomedical applications, special biomedical image processing languages have to be developed. The combination of both hardware and software leads to clinical imaging devices. Two different types of clinical imaging devices have been discussed. There are radiological imagings which include radiography, thermography, ultrasound, nuclear medicine and CT. Among these, thermography is the most noninvasive but is limited in application due to the low energy of its source. X-ray CT is excellent for static anatomical images and is moving toward the measurement of dynamic function, whereas nuclear imaging is moving toward organ metabolism and ultrasound is toward tissue physical characteristics. Heart imaging is one of the most interesting and challenging research topics in biomedical image processing; current methods including the invasive-technique cineangiography, and noninvasive ultrasound, nuclear medicine, transmission, and emission CT methodologies have been reviewed. Two current federally funded research projects in heart imaging, the dynamic spatial reconstructor and the dynamic cardiac three-dimensional densitometer, should bring some fruitful results in the near future. Miscrosopic imaging technique is very different from the radiological imaging technique in the sense that interaction between the operator and the imaging device is very essential. The white blood cell analyzer has been developed to the point that it becomes a daily clinical imaging device. An interactive chromosome karyotyper is being clinical evaluated and its preliminary indication is very encouraging. Tremendous efforts have been devoted to automation of cancer cytology; it is hoped that some prototypes will be available for clinical trials very soon. Automation of histology is still in its infancy; much work still needs to be done in this area. The 1970s have been very fruitful in utilizing the imaging technique in biomedical application; the computerized tomographic scanner and the white blood cell analyzer being the most successful imaging devices...