User manual

Science Manual – Using Video Images for Fisheries Monitoring 21
configured. In reality, an image analysis system requires at least a portion of the
detected events to be verified visually by an operator.
3.7.2 Fishtick, the motion detection software system
Fishtick is an image processing software package developed by the Oregon-based
company Salmonsoft. It consists of a capture programme, FishCap, and a review
programme, FishRev. There are a number of different versions suitable for different
purposes. Fishtick Gold was assessed in this project and this is the version referred
to throughout this manual. FishCap captures images using motion detection or
tripwire algorithms. The user is able to configure the programme for a particular site
by setting regions of interest and then masking out areas within these regions (Figure
3.7) which may affect the capture process, such as weed waving in the current. The
motion detection algorithm compares successive frames, looking for a large enough
block of movement to be a fish. The user must set the size of the changed area
which will generate a detection as well as the pixel threshold where, if a sufficiently
large block of pixels shows enough change, a detection is triggered. Details of the
parameters which can be set and instructions on how to use Fishtick are provided in
Fishtick Fish Passage Monitoring System User’s Manual, included in Appendix 8.
This manual also gives the required PC specification for Fishtick.
Figure 3.7: FishCap display screen showing how a quad input can be
processed using four separate regions. An area of the top left image has been
masked off.
The tripwire algorithm uses a series of up to 25 ‘tripwires’ to detect fish; however, this
method works best when turbulence is low, water clarity is good, and lighting is