图像处理问题 - 将Standard-Def转换为Hi-Def，我是否必须丢失图像数据？

I'm writing a small program to convert a standard definition 4:3 video to a hi-def video 16:9 and I'm experiencing a serious stretching effect, as expected I suppose (though I didn't think about it until my code started working). Anyhow, the only way I can think of getting around this stretching effect and still fill the whole 16:9 screen is to cut off the top and bottom of the image. I'm writing a small program to convert a standa