Discussion in 'General TV Discussions Forum' started by christhedon, Aug 12, 2004.
Also what is progressive scan? Do they all have it?
I have a Toshiba 36" picture frame 2 and it has a fantastic picture as well as being the best looking crt on the market imo.
Progressive scan produces a sharper more cinematic picture that can be accessed with a compatable dvd player.
Mine is for sale in the classified section if you're intrested in buying one (i'm on the Upgrade path again!)
Progressive scan - a normal tv signal is made up of 625 lines (of which only 575 actually contain picture information but let's not go there). the 625 lines are made up of two lots of 312.5 lines interlaced (think intertwined) together to make the full 625 lines. So to begin with we display the first 312.5 lines and then display the second 312.5 lines which 'optically' are originated 'in between' the first set of 312.5 lines. If you like they are shown sequentially after each other and your eye thinks it is seeing 625 at the same time. We display these two sets of lines so quickly that your eye merges them together and it happens so fast that you do not see the flicker that would otherwiae be apparent. (Look out the window and try opening/closing your eyes as fast as you can - you see flicker because you can't open/close your eyes fast enough - a tv set can !" however, on a big screen the image is so BIG and so CLOSE that you can discern the flicker. So how do we get around this, Your 'posh' tv set takes these two sets of lines and merges them together to get the full 625 in a 'oner'. It then displays it to you on your BIG screen much more quickly than your old SMALL screen, so quickly in fact that you do not see any flicker that you mihght otherwise have seen. So - interlaced = two sets of 312.5 lines, progressive = 625 lines all in one go. regards, yt.
So what's the point of 100Hz? I thought that was to reduce flicker........
Yes you're right. The 312.5 lines are presented sequentially to your eye at 50Hz (50 times a second). The other set of interlaced 312.5 lines are shown at 50Hz - but they are interleaved (intertwined) with each other so the COMPLETE PICTURE of 615 lines is presented to your eye at half the rate of the individual 'fields', ie, 25Hz - with a small(ish) display this would be ok because your field of vision is concentrated in a smaller area, with a larger display there is an increased likelyhood you would perceive the flicker. With progressive pictures (as explained in the previous post) the complete picture is shown to you at 100 hz - much much faster, so you don't see the flicker - but there are other subjective factors inherent in this, inter field motion artifacts etc
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