Auto Raster Log Digitizing is a popular problem in oil & gas industry, where geologists would like to digitize data points on an analog raster log (normally being fed into the system as a scanned image). This is a heuristic algorithm to solve the aforementioned problem, with 3 steps:
1) Preprocess the image: thin the image then remove vertical grid lines
2) Wait for user input to pick the starting point
3) Start from that point, run Breath First Search algorithm to find the longest possible path down the image (assuming the path of the log curve will be longer than any other paths). If the algorithm hits a dead-end (possibly because of bad image quality), try to look for a closest nearby point and continue the process from that point.