Digital imaging | Digital imaging
Key Words: Telepathology, EQA, CCD, Bayer Filter
Definition:Images created through the capture of light by light sensitive sensors (pixels) on the surface of a CCD
Digital images are made up of millions of tiny squares called picture elements or pixels: the more pixels in a specified area, the higher the resolution of the image and the more it can be enlarged before the separate pixels start to show. Resolution is also often quoted as the size of the image, for example, 1600 x 1200 pixels or the total number of pixels present, in this case, 1.9 million or 1.9 megapixel.
As light enters a color digital camera, it passes a filter (Bayer Filter), which allows either red, green or blue light to reach the underlying pixels. This creates an image where individual pixels only have their respective color information. The overall full color image is generated through interpolation of information from adjacent pixels. Light rays are then directed to the CCD, which converts light into electrical charges proportional to the intensity of the light coming from the subject. Each pixel specifies brightness and color.
Digital imaging provides easy image storage, manipulation and management. With appropriate image analysis software, images can be readily analyzed, annotated, stored and retrieved. There are no processing costs, images can be viewed immediately after capture, and images can be readily shared with multiple users via the Internet and web based browsers. Digital imaging also enables the creation of 'virtual' microscopy slides, where all fields of view at all magnifications can be digitized and observed on a PC (without the need for a 'conventional' microscope).
The ease and convenience of digital imaging makes it central to all microscope imaging applications. Digital imaging is fundamental to telepathology and teaching applications where remote users can simultaneously study the same image. Digital imaging is also a key tool in quality control and for good laboratory practice (GLP) where appropriate imaging software can record when images were captured, by whom, and all image manipulation and annotation events.
Digital cameras can be fitted to microscopes, with a trinocular tube or camera port, using appropriate mounts.
Choice of camera will depend on the application and the end use of the images. A great variety of digital imaging cameras are available, for example, for rapid, high temporal resolution imaging (e.g. DS-1QM), low light fluorescence imaging (e.g. DQC-FW, DS-5Mc, and ultra-high resolution (e.g DXM1200F).