here is a VS2008 sample to illustrate the effect: www.j-k-s.com/test/ScaleTest.zip (compile in 32 & 64, and see the difference by scaling the window to force redraw).
any idea what's going wrong?
Some experiments with VS2008 and VS20010 have shown that the compiler works incorrectly with structures. So different threads process the same piece of image.
There is an error in MS compiler :(
We recommend to use (1st or 2nd or 3rd):
- Intel compiler. It works right!
- Dynamic or threaded static libraries instead external parallelization with statics. They have parallelized version of resize.
- Workaround. To write a wrapper in which structure is replaced on separate variables.
if(id == nt-1) dr.height -=dr.y;
if(id == nt-1) dr.height = droi.height - droi.y;
2. the last slice can be non whole for any image size
dr.height = droi.height % nt
dr.height = droi.height / nt;