Convert images of seismographic plots to comma-separated data

This is a graphics-to-data conversion task. The deliverable is only the converted data. Any tools can be used, and no code needs to be delivered. I have three images of seismographic data, each 10600*3400 pixels (jpg format). Each image has 50 horizontal lines of plotted data. The images are attached in this project description. I would like the images converted to three ASCII files of comma-separated values ranging from -1 to +1. There should be a value for each 3 horizontal pixels. NOTE: Some of the plots cross into other plots above and below, some lines are slightly weak, and there are a few scribblings on the images. Some manual cleanup is probably necessary. Deliverables: 1) Three ASCII files of comma-separated values ranging from -1 to +1. 2) Three corresponding PNG images with a single horizontal line plotted from the values, at 3 pixels per horizontal value, 400 pixels high.