Help With Levels

[EpheMeroN]

Can someone help me correct the levels? The final output is going to be MPEG-2 and watched on a tv. This was taken from The Howard Stern Show.

http://img49.exs.cx/img49/1667/238.png

http://img49.exs.cx/img49/5285/239.png

http://img49.exs.cx/img49/3448/240.png

[Mug Funky]

the levels look about right, except the black-level is a tad high.

the third frame is beyond help - it's overexposed, so you obviously can't un-overexpose it.

try levels(24,1,255,8,235). that'll get you into CCIR-601 luma range (so you'd better tell your mpeg encoder not to do that bit for you, or it'll undo the level correction).

btw, that was just a guess.

the easiest way to figure levels is by using the levels filter in virtualdub and reading the figures off it. move the gamma slider around to be able to see the extreme ranges easier (but remember to move it back when you're done)

[edit]
btw, you've got some awful interference there. are you using an indoor antenna? those vertical lines look familiar to me.

[EpheMeroN]

I have tried the levels filter from Vdub. I just don't quite know a) how to set it up properly, and b) how to transfer its numbers to an AviSynth script.

And yes, there is some bad interference w/ that analog noise. I actually have a coaxial cable into my ATI Capture Card but at the time I captured that, my cable company was experiencing problems w/ channel quality. I have been trying to think of ways to filter out some of that noise the entire day... any ideas?

[oo_void]

I though the CCIR-601 range was 16 to 235 for luma (going from the AviSynth docs), not 8 to 235...

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oo_void

[EpheMeroN]

Correct me if I'm wrong, but isn't CCIR-6601 for DV video?

I too, thought 16-235 was the range for televisions and 0-255 was the range for computer monitors.

[hartford]

This is what you do:

Copy this to an avs file:

avisource("my-video.avi").convertToYUY2()
Coloryuv(Analyze=true)


Load the file in VirtualDub. Look at the "Y" column and
take note of the "Maximum" and "Minimum" numbers. Scan through
the file to be certain of the Min and Max.

Load the "levels" filter in VirtualDub.

The "input" levels are those that you saw in the avs file.

The "output" levels are 16 - 235 for NTSC.

As for the "over-exposed" to which Mug Funky alluded, you most likely
will need to process that section seperately.

Best.

[Didée]

Originally posted by Mug Funky
it's overexposed, so you obviously can't un-overexpose it.
Well, for over-exposed areas one could try to fiddle something with a gaussian blur at big radius, restricted to the clipped areas. Should of course be soft-masked, e.g. build a mask by taking the clipped areas, apply a gaussian blur to that one etc. pp. - you get the idea.

[EpheMeroN]

I would like to treat that one area of the video separate for it is overexposed. How can I do that all within 1 single script? Or will I have to cut the AVI up and treat the 2 segments separately?