This collection showcases the step-by-step process followed to create "Calque", 
a web tool designed for manual data extraction from graph images. It works like 
tracing paper, except that the notebook enables the extraction of CSV data. 

Christophe Yamahata

Spline Editor (without bug)

Spline Editor / Splice: Insert control points between existing ones

Closest Point on Line: Solution with multiple control points

Logarithmic and linear scale bars

Draggable axis with arrow

Draggable axes with arrows

Calque (tracing paper)

On-line tool: Calque

Curves and graphs