The term microscope image defines and describes the use of digital image processing techniques to process, analyze and present images obtained from a microscope. This processing technique for microscopes is now commonplace in a number of diverse fields such as medicine, biological research, cancer research, drug testing, metallurgy, etc. Many of the manufacturers of modern microscopes now specifically design in features and add in new innovations that allow the microscopes to interface to an image processing system.
Most microscope image acquisition in video microscopy applications was typically done with an analog video camera, often simply closed circuit TV cameras. While microscope image acquisition required the use of a frame grabber to digitize the microscope images, video cameras placed in modern microscopes provide microscope images at full video frame rate of 25-30 frames per second, allowing live video recording and processing. While the advent of solid state detectors yielded several advantages for the acquisition of microscope images, the real-time video camera was actually superior in many respects.
Nowadays, acquisition of microscope images is usually done using a CCD camera mounted in the optical path of the modern microscope. The camera may be full colour or monochrome. Very often, very high resolution cameras are employed to gain as much direct information as possible, in order to minimize the noise in a microscope image. Cryogenic cooling is also commonly used to improve microscope images. Most of the times digital cameras used for modern microsocpes provide pixel intensity data to a resolution of 12-16 bits, much higher than is used in consumer imaging products. Ironically, in recent years, a lot of effort has been put into acquiring data at video rates, or with 25-30 frames per second or higher. What was once easy with off-the-shelf video cameras now requires special, high speed electronics to handle the vast digital data bandwidth.
A higher speed acquisition of microscope images gives way for dynamic processes to be observed in real time, or stored for later playback and analysis. If combined with the high microscope image resolution, this approach can generate vast quantities of raw data, which can be a challenge to deal with, even with a modern computer system. It should be observed that while current CCD detectors allow very high image resolution for microscope images, often this involves a trade-off because, for a given chip size, as the pixel count of the microscope image increases, the pixel size of the microscope image decreases. As the pixels get smaller, their well depth of the microscope image decreases, reducing the number of electrons that can be stored. In turn, this results in a poorer signal noise to radio.
To acquire the best microscope image results, one must select an appropriate sensor for a given application. Because modern microscope images have an intrinsic limiting resolution, it often makes little sense to use a noisy, high resolution detector for microscope image acquisition. A more modest detector, with larger pixels, can often produce much higher quality microscope images because of reduced noise. This is especially important in low-light applications such as flourescence microscopy which requires optimum microscope image quality. In addition, one must also consider the temporal resolution requirements of the application. A lower resolution detector for the microscope will often have a significantly higher acquisition rate, permitting the observation of faster events. Conversely, if the observed object is motionless, one may wish to acquire microscope images at the highest possible spatial resolution without regard to the time required to acquire a single microscope image.
