1>glpng.lib(pngerror.obj) : error LNK2019: unresolved external symbol __iob referenced in function _png_default_error
"__iob" is in "libc.lib" or "libcd.lib", but if you included those libraries, you might meet another errors such as unresolved external symbols.
However, the newly compile library doesn't require __iob any more, so it can be solved through using the new library. glpng 1.45 Visual Studio 2008 project can be found here. Refer following site: http://sites.google.com/site/collagefactory/programs-1/glpng-1.45_vs2008.7z?attredirects=0
For more information: