Why is image shrunk?

I read a windows BMP image, the bit map is untouched, and use following code to draw it in a OpenGL window:
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
glRasterPos2i(1, 1);
glDrawPixels(width, height, GL_BGR_EXT, GL_UNSIGNED_BYTE,

the image is strangely shrunk!

I didn’t use glPixelZoom(…) or any pixel transfer operations.

Would anyone tell me the reason that can cause this problem?

Thank you!


What do you mean by “shrunk”? Smaller than you’d have thought, smaller than the image as displayed in your paint package, lines of pixels missing?

A screenshot would be helpful.