Manual stereology systems require that a test system (e.g. a grid of points on celluloid) be placed over a photograph. The user then indicates each intersection of the test system with the targets in the photograph. A computer records the "hits", and provides data summaries.
An image analyzer makes measurements from digital images (as opposed to photographs). The advantages of using image analysis in stereology are summarized, below.
Test system generation
Any type of test system can be generated, digitally, and appears directly over the image of the specimen.
Automated target detection
The better image analyzers can automatically determine where intersections with targets occur, using a combination of density and spatial criteria set by the user.
The computer can apply the principles of sampling and measurement in consistent ways. The danger of biased sampling is reduced.
Flexible image acquisition
The imaging system can analyze photomicrographs, but it also allows us to form images without an intermediate photographic step. Acquire images, directly, from video cameras, cooled CCD cameras, phosphor plate imagers, or other devices that generate digital data.
Multiple images can be used to localize specific tissue components
We can use combinations of images (e.g. fluorescent and brightfield) to make stereological measurements on specific populations of labeled targets.