View Full Version : Interlacing destroys color


lnx64
08-19-2012, 01:55 PM
I know this is going to sound weird, but I have noticed that interlaced programming seems to have worse color qualities than a non-interlaced signal (like 240p for example).

I know in the signal itself, it's the same.. On an LCD or plasma, they look the same in color.

But on a CRT, it seems color quality on a interlaced signal is just, different. ALL CRT's I have used or seen (including my friends roundie), exhibit this same thing.

Unless of course it's just me.

(EDIT: Whooops! Wrong board! Sorry.)

old_tv_nut
08-19-2012, 07:30 PM
What's with the "whoops?" Did this get moved here from the wrong place or has it been moved from here to somewhere else?

lnx64
08-19-2012, 08:07 PM
I accidentally posted it here in the broadcasting gear board.. I don't think it actually belongs in this board but perhaps a different board.

old_tv_nut
08-19-2012, 08:44 PM
Well, how about Television Broadcast Theory then?

lnx64
08-19-2012, 08:49 PM
That'd be fine, but I don't have the authority to move posts.

old_tv_nut
08-19-2012, 09:03 PM
I think you may have capability to remove your own post. You could see if it works, then you could repost in the other forum.

Meanwhile, maybe a mod can move it.

lnx64
08-19-2012, 09:05 PM
No thread deleting capabilities for me.

So a mod will need to move it for me.

old_tv_nut
08-19-2012, 09:07 PM
Well, I see it's copied over, so on with the discussion!

Could you explain a little more what you mean? Are you talking about the same program viewed as interlace and as progressive scan? On the same TV or separate TVs?

lnx64
08-19-2012, 09:14 PM
Same program, same TV.

I've noticed this for all TV's.. Basically, even on a color bar generator that allows both interlaced and non-interlaced, at least to my eyes, I've noticed that the color bars look better when non-interlaced/progressive scan.

I don't know if it has to do with the phosphors in a line getting 1/2 less the beam or what, but it just seems the colors seem more dull (or darker).

It could though very well be just my imagination.

old_tv_nut
08-19-2012, 09:17 PM
I don't understand how you are looking at both interlace and progressive on a roundie, which can only display interlace?

Edit: oops - i see now you aren't talking about 525 (480) progressive, but 240 progressive.

I'm surprised that you see any color difference, although you could see some inter-line flicker (or "twitter") in the interlaced case.

old_tv_nut
08-19-2012, 09:25 PM
CRT phosphors decay within one scan field (except for some low level persistence), so the two cases should appear the same brightness and color to the eye.

The two cases definitely will be different for a well focussed camera shot, however. The average brightness is the same, but the line-paired (progressive) case means the photo has to try making the same average brightness from a combination of overexposed scan lines and black spaces. The visual system has separate processing for average brightness and detail and doesn't saturate on the progressive scan lines the way a camera does.

old_tv_nut
08-19-2012, 09:29 PM
Another thing - many analog sets have imperfect interlace such that line pairing will come and go as you adjust vertical hold slightly. It would be interesting to perform this experiment and report what you see as interlace comes and goes.

old_tv_nut
08-19-2012, 09:32 PM
And another question - does the effect depend on how closely you view the screen?

lnx64
08-19-2012, 09:52 PM
Doesn't seem to affect viewing difference, but I usually view within 10ft.

old_tv_nut
08-20-2012, 09:57 AM
Are you seeing the line structure more (brighter lines separated by darker spaces) in the non-interlaced case?

lnx64
08-20-2012, 10:13 AM
Yes, the scan lines are more pronounced to me in a non interlaced mode.

old_tv_nut
08-20-2012, 12:03 PM
Ok, now my question is, do you see a difference in color if you view from a long distance, like 20 feet or more, where you can't see the lines even in non-interlace mode?

lnx64
08-20-2012, 12:24 PM
I don't know, I haven't been able to perform this experiment in a room large enough to get that far away.

old_tv_nut
08-20-2012, 03:10 PM
I don't know, I haven't been able to perform this experiment in a room large enough to get that far away.

Fair enough, but that's what you need to do to see if it's a visual effect rather than the set itself. You should at least try at whatever max and min distance possible. I'm guessing it's visual, but not confirmed yet.

Psychophysics is strange and wonderful stuff!

lnx64
08-20-2012, 10:00 PM
Ok I tried this in the cafeteria at work where they use Sony Trinitron TV's at work.

From a distance it looks the same to me.. Up closer I see a difference.