从Scrimage Image实例获取图像格式

I'm working with scrimage right now, and I need to get the image format from the file, as right now, if a GIF is uploaded, it will not become an animated JPEG. I need to be able to tell if the image file is a GIF so I know to not use the Format.JPEG writer. Is there any way to do this?I'm working with scrimage right now, and I need