chartarea

How can i save the usertexture and userpicture
that is filled in the chartarea and the plotarea object of the chart to
a jpegfile in C#?

for eg: for getting the chartarea object i do like this,
but not sure of the how we can save the userpicture and the usertexture that
is embedded inside the chartarea.

Excel.Chart chart=worksheet.activechart;

Excel.ChartArea chartArea=chart.ChartArea;