Picture format on the simple definition digital receiver output is 720 horizontal pixels and 576 vertical pixels.
For economic resons, provider can boradcats a TV with pictures with less resolution (less pixels).
To show this, some example of test cart broadcasted with different resolutions.
Test cart with max SD resolution 720x576:
We are looking on a detailed part of the test cart (yellow part), and compare picture with other test cart with less resolution.
resolution of 528x576:
resolution of 480x576:
resolution of 352x576:
We can see the effects due to less resolution, only the full resolution (720x576) do not alter the picture.