Now,I can read data from a DEM file into an array,but I do not know how to use it to create a png file? Thk u. BTW,Some one tell me that freeimage can do it,but I do not know. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20100405/ace0e3f2/attachment.html