PB 判断图片格式属于那种图片

If long(BlobMid(lb_data,1,4)) = 944130375 Then  
	ls_temp = 'gif'
ElseIf long(BlobMid(lb_data,7,4)) = 1179207242 Then  
	ls_temp = 'jpg'
ElseIf integer(BlobMid(lb_data,1,4)) = 19778 Then  
	ls_temp = 'bmp'  
ElseIf long(BlobMid(lb_data,1,4)) = 1196314761 and long(BlobMid(lb_data,5,4)) = 169478669 Then  
	ls_temp = 'png' 
Else   
	ls_temp = 'none' 
End If