D>> >>
>>> Reverse video to give higher transmission power during black was chosen,
>>> because noise is more visible to the eye in the black levels of video.
>>> With the whites, noise is less visible to the eye. Therefore the higher
>>> transmission power levels in black levels allow for less visible noise
>>> due to any RF carrier signal loss.
>>
>> So do you think the noise gets smaller during the higher parts of the
>> signal (the blacks)? Let me assure you it doesn't. The amplitude of
>> the noise in the black area is identical whether it is placed at the
>> top of the modulation or the bottom. Noise adds linearly to the
>> signal, it doesn't multiply. It makes not a jot of difference to the
>> noise whether black it at the top, or whit is.
>>
>> The polarity of the signal is all about making every frame identical
>> in height so that each component of the signal can be identified
>> unambiguously.
>
>It's easy to see even fairly dim stars against a dark nighttime sky.
>Seeing black specks against a bright daytime sky is much harder. The
>contrast ratio may be the same, but size matters.
>
>Jerry
The "farmer" that discovered Pluto after years of intensive slide examination knows a thing or two about contrast.
The plates were all developed so the examiner got black "stars" or "objects" on a white "space" background.
There is a reason for this. It has to do with the human eye, and how the brain processes visual information.