Ycasd
ycasd captures and scales data
...It can be used for retrieving data points from figures of electronically available or scanned publications for which no raw data is provided. After the figure is displayed on the screen, it only requires the definition of two pixels on each of the axes by clicking and setting their corresponding values. For each subsequent click on the figure, a coordinate pair is estimated by vector calculations and in accordance to axes definition. For more details, see http://www.biomedcentral.com/1471-2105/15/219#Sec5.