You should do some research into ASPECT RATIOS and the phrase Original Aspect Ratio ("OAR")!!
A SD picture has an OAR of 4:3 and when displayed on a 16:9 HD TV should have black bars on the sides !! If it does not, it means you are either distorting the image horizontally or you are cutting off the top and bottom of the image. Neither is an acceptable solution.
An HD image with an OAR of 16:9 displayed on a 4:3 screen should have black bars on the top and bottom. If not, the image is being distorted vertically or the sides of the image are cut off; again, neither is acceptable.
For all the myriad of similar issues, see the link I provided above.
A SD picture has an OAR of 4:3 and when displayed on a 16:9 HD TV should have black bars on the sides !! If it does not, it means you are either distorting the image horizontally or you are cutting off the top and bottom of the image. Neither is an acceptable solution.
An HD image with an OAR of 16:9 displayed on a 4:3 screen should have black bars on the top and bottom. If not, the image is being distorted vertically or the sides of the image are cut off; again, neither is acceptable.
For all the myriad of similar issues, see the link I provided above.