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Translucent logos

Posted: Mon Apr 26, 2010 4:07 pm
by drbenjamin

I have a show that Comskip struggles with, and while playing around with my .ini file I noticed that the logo is translucent; you can see it but the background shows through, so the logo color is not uniform. Can Comskip deal with this? If so I'll go to the effort of clipping out a bit of show that contains the logo to get a good bitmap. On this particular show the beginning contains a whole bunch of interleaved (logoless) ads and (logo containing) show previews, so I think it would be hard to detect the logo even if it were a solid color.


Re: Translucent logos

Posted: Tue Apr 27, 2010 8:23 am
by erik
Comskip is designed to deal with this.
Maybe you can try some different settings of logo_filter
It normally is at 0 but you can try 2 or 4


There are some settings to do detailed tuning of the logo learning and matching but these are very complicated to improve.

Re: Translucent logos

Posted: Tue Apr 27, 2010 3:16 pm
by drbenjamin
Hi Erik

Thanks for the reply. I ended up clipping out a section of show with a fairly clear logo, and comskip managed to find it. I have been trying to improve the mask by hand editing it and have a few questions about the mask file format. It looks like the "|" symbol indicates left right contrast, the "-" indicates up down and the "+" indicates 45 degrees - is that right? Also, should the symbols just trace the edge of the logo or should they cover over both sides of the transition from background or logo?
Last, unrelated q - when I'm reviewing a h.264 HD .ts file, there is no video, is that expected? I seem to remember you saying that somewhere but can't find the post.

Thanks for a great program!

Re: Translucent logos

Posted: Tue Apr 27, 2010 3:28 pm
by erik
The "+" signals both horizontal and vertical transition so that is often 45 degrees
The symbols track all bit positions where you always expect a transition due to the logo
The detection spans 4 pixels so on small logo lines you cover the whole surface, on big patterns you cover the edges, that is both transitions (background -> logo and logo->background)
previewing h.264 does not work very reliable, sorry.....

Re: Translucent logos

Posted: Fri Apr 30, 2010 2:05 am
by drbenjamin
Thanks Erik, my hand-edited logo files are really improving commercial detection - the logo detection is now bang-on accurate.
erik wrote:previewing h.264 does not work very reliable, sorry.....
Do you mean it doesn't work at all, or is there anything I can do on my end to enable it? It makes huge diff to see how the logo overlaps with the mask.


Re: Translucent logos

Posted: Fri Apr 30, 2010 6:39 am
by erik
You can use comskipGUI to see during detection how the mask fits the logo