Resources are contained inside EXEs and DLLs and thus occupy virtual address space that doesn't change during the life of the process. It is therefore easy to read a resource directly. If you need to access a bitmap, for example, you can get the DIB address with code like this:
LPVOID lpvResource = (LPVOID) ::LoadResource(NULL, ::FindResource(NULL, MAKEINTRESOURCE(IDB_REDBLOCKS), RT_BITMAP));
The LoadResource function returns an HGLOBAL value, but you can safely cast it to a pointer.