PointCloudLibrary/pcl — pull request #528 by sksavant (2014-02-26 15:22:55+00:00)
Title: Add savePNGImage function for histograms.

Render the histogram using vtk offline and then save the image to png
file.

Function flow is imitated from addFeatureHistogram in HistogramVisualizer.

ref: http://www.pcl-users.org/How-to-save-a-histogram-in-a-PNG-or-JPG-file-td4032197.html