将PNG复制到更大的空白/代码生成纹理的最佳方法？ （OpenGL ES 1.1 / iPhone）

I have a 320x480 PNG that I would like to texture map/manipulate on the iPhone but these dimensions are obviously not power of 2. I already tested my texture map manipulation algorithm on a 512x512 PNG that is a black background with a 320x480 image superimposed on it, centered at the origin (lower left corner (0,0)) where the 320x480 area is properly oriented/centered/scaled on the iPhone screen.I have a 320x480 PNG that I would like to textu