The automatic method proposed to count colonies includes four steps, i.e., eliminating noises outside agar plate, removing plate rim and wall, identifying and separating clustered or overlapped colonies, and counting colonies by using connected region labelling, distance transform, and watershed algorithms.
The colony counting problem can be easily solved by using the "CountThings By Camera" mobile app. You only need to take a photo, click to identify, and the whole process can be automatically completed, and the accuracy can also be adjusted.
You can download it at google play named "CountThings By Camera"