There seems to be an error in the entry for clEnqueueWriteImage in the OpenCL 1.0 HTML Reference Pages. http://www.khronos.org/opencl/sdk/1.0/docs/man/xhtml/clEnqueueWriteImage.html It reads:
Enqueues a command to write from a 2D or 3D image object to host memory.
But it should really be indicating the opposite direction, for instance:
Enqueues a command to write to a 2D or 3D image object from host memory.
In the official spec is correct, however there it is a common entry for clEnqueueWriteImage and clEnqueueReadImage, something probably went wrong when that text was refactored into two separate entries.