The online documentation for clEnqueueWriteImage at http://www.khronos.org/opencl/sdk/1.0/docs/man/xhtml/clEnqueueWriteImage.html has the following line for the function description (right under the header):
"Enqueues a command to write from a 2D or 3D image object to host memory."
Obviously, the line was copied from the clEnqueueReadImage page but not modified properly.
The line (comparing to clEnqueueReadImage and clEnqueue[Read|Write]Buffer) should be:
"Enqueues a command to write to a 2D or 3D image object from host memory."