How can I draw a circle on top of a cgimage in IDL? This question is similar to this question:

Generally, the cgimage coordinate system is not the same with device, so a conversion is needed to do so:

cgImage, googleImage[0:2,,], Position = position, /noerase, $ /Keep_Aspect, OPOS=outputPosition print,outputPosition dummy_x = 0.5 * (outputPosition[0] + outputPosition[2]) dummy_y = 0.5 * (outputPosition[1] + outputPosition[3]) cgPlotS, dummy_x, dummy_y, PSYM=’filledstar’, SYMSIZE=3.0, COLOR=’red’,/normal