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Author Topic: Blue Flouresent Edge To Objects On A TV Screen !!..what is it ?  (Read 3931 times)

Offline neilep

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This may only apply to conventional TV's ie: not plasma, not LCD, Not Progressive scan or HD models ...(but I'm not 100% sure on tat)

....but why when watching films (mostly on DVD) do I very often see a blue/purpley edge to objects and people and stuff ?

Have ewe seen it ?...do ewe know what I mean ?


 

Offline Seany

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Sorry! I don't understand! LOL!
 

Offline neilep

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Sorry! I don't understand! LOL!

Sometimes, I can see a clear blue/purple edge to objects when watching DVD's...be it the edge of a tree or a person !!...you don't see it ?...it's obvious....even when pausing !
 

Offline Soul Surfer

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It could be a result of the analogue filtering to increase the perceived sharpness of the image.  In an analogue TV signal the colour signals have a rather poor bandwidth and colours tent to wash into each other.  the black and white information has the best resolution but sharp edges are often slightly enhanced by having a slightly rising frequency response to blot out this colour blurring and make the picture appear a bit sharper than it really is.  some TV sets allow you to change this emphasis (a bit like a treble control in an audio system and call it the "sharpness" or "noise reduction"  control  because having it turned up will also enhance high frequency noise in the signal.
 

Offline Seany

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What blue line? :P
 

Offline JimBob

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It could also be due to a poorly synchronized signal processing.
 

another_someone

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On still photographs, what you describe is what is often referred to as purple fringing (usually only happens when you have a very high contrast), and is a consequence of chromatic aberrations; but I am not at all sure that this is the case for what you are describing with movies (not that I have had cause to see it happen with movies - and I would be very disappointed if they allowed significant chromatic abberation with any professional photography, even professional movie photography.
 

Offline neilep

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THANK YOU all for your answers...what I will do is next time try and photograph the phenomena and post it here for you....hmm..I wonder if it can be photographed !

Your mention of high contrast George may be it though..........it happens on old Black & White movies too.

In fact Ians response rings true too..THANK YOU IAN ...as does JimBobs !!..LOL...could you ALL be right ?
 

another_someone

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You cannot get chromatic aberrations on monochrome film.

Another possibility I would add is a poorly focusedelectron gun (if you have a 3 gun tube - not relevant if you have a single gun tube), or a slipped colour mask on the tube.
 

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