Unusually dark Xvid AVIs

[resonator]

Hi. Just did a search, but I don't know exactly what I'm looking for, so sorry if this is frequent question.

Sometimes I get my hands on certain XVID AVI files and they are extremly dark. My guess would be that this comes from multiple colorspace conversions or something, as this is a HDTV->DVD->XVID-rip (don't know why programs where used though), but then I'm absolutly not an expert when it comes to colorspaces and the effects when converting between them.

Anyway, I wonder if one could use level() to correct the dark picture? And what would be the correct settings for something like that?

[lamer_de]

Easiest way would be to use ffdshows "picture properties" page to adjust it on-the-fly. Playing around with the levels tab is also worth a try.

CU,
lamer_de

[resonator]

It's not about computer playback but about encoding SVCDs from these kinda sources. I guess opening a screenshot in Photoshop and fiddling around with the levels there might be more accurate, but nevermind though, I'm doing tests at the moment and I think I've figured it out.

[sh0dan]

You can use:

Levels() to adjust brightness in a nonlinear fashion. Use ffdshow to get the values.
Tweak() to adjust contrast/brightness
ColorYUV() to adjust all the things above, and more.

Use ColorYUV(analyze=true) and Histogram() to get information on how your luma is distributed. You could perhaps try and put up a link to a few seconds of video.

[resonator]

Hey, thanks a lot for offering your help, but I've already figured it out.

[Guest]

@resonator

When you post a problem and then find the answer yourself, you need to post the solution you used, so that others may benefit. Thank you.

[resonator]

The reason I didn't post a solution is very simple - there is none. I mean, I previewed the outcome of my very basic script without any processing besides resize/addborders in VDub and thought the picture was way too dark. However, I did a partial encoding and burned it on a CDRW and on my TV the picture looked just fine, so I just misjudged the source.

Btw, if this is of any interest to you, the shows I tried here were "Angel" and "Alias", both kinda dark shows.

So, sorry. Next time I'll do more tests before I ask for directions.