lines with bad colors

[mathmax]

Hello,



I would like to fix the green & pink lines at the top.. and to understand the origin of the problem.

Thank you in advance for any answer

[hech54]

Are you still trying to beat this dead horse video?.....

[mathmax]

yes... I'm crazy

Any advices?

[poisondeathray]

You can do it manually in photoshop or AE , with rotoscoping , feathered masks and clone stamp tool to "airbrush"

I think that's the only way you'll get decent results, even on your "halo" bits in the other thread. Automated detection is too inaccurate, you destroy good parts and miss bad parts.

smoothuv(radius=maybe 5-7) will get rid of some rainbows , but you would have to apply it differentially (e.g. through masks) to target different areas. Since the defect is much stronger at the top, but still present throughout the frame. Even doing it this way will leave a desaturated mess up top. I think the best way is to fix this manually.

[jagabo]

Post a video sample.

[mathmax]

Thank you for your answers.

Here is a video sample : http://www.mediafire.com/?z2nz1jzodrm

I would prefer to avoid editing the video manually...
And I would really like to understand what is the problem.

[jagabo]

I believe the problem stems from time base errors causing the chroma burst signal to shift resulting in misinterpretation of the color channels. Maybe from misaligned heads on the VHS deck?

About the only filter I've seen that does much with colors that bad is Chroma Noise Reduction by Gilles Mouchard for VirtualDub. It helps a lot if you set everything to the max. But it's still far from perfect.

A really strong TemporalSoften() or the chroma channels will do something similar.

There's always GrayScale() too. LOL

[kopmjj]

I believe the problem stems from time base errors causing the chroma burst signal to shift resulting in misinterpretation of the color channels. Maybe from misaligned heads on the VHS deck?

About the only filter I've seen that does much with colors that bad is Chroma Noise Reduction by Gilles Mouchard for VirtualDub. It helps a lot if you set everything to the max. But it's still far from perfect.

A really strong TemporalSoften() or the chroma channels will do something similar.

There's always GrayScale() too. LOL

hi me and mathmax are working on this too, i have managed to remove the halo in after effects but regarding this color issue, i can get rid of the bad color lines using fft3dfilter on chroma with sigma=30 or higher and then if i use a slight blur it smooths the bad color area, do you think im going in the right direction with this? and also anymore advise? thanks.

[mathmax]

About the only filter I've seen that does much with colors that bad is Chroma Noise Reduction by Gilles Mouchard for VirtualDub. It helps a lot if you set everything to the max. But it's still far from perfect.

A really strong TemporalSoften() or the chroma channels will do something similar.

There's always GrayScale() too. LOL

Ok but I guess all these solutions will blend the colors more than fixing the problem.. it could works if you have on line or two with bad colors, but as many lines of the top are bad colored it'll just leave the clip with green and pink areas...
I think it's possible to correct the colors line by line by comparing it with other lines (spatial or temporal comparison). Is there any ready script or software to achieve this or is it necessary to write a custom procedure for that?
After fixing 90 % of the colors this way, a temporalsoften() or spatialsoften() should do the rest...

[jagabo]

Ok but I guess all these solutions will blend the colors more than fixing the problem.. it could works if you have on line or two with bad colors, but as many lines of the top are bad colored it'll just leave the clip with green and pink areas...

Yes, they blend temporally. The flickering of the colors will be reduced but it they are the wrong color for an extended period they will remain the wrong color. And turning the filters up enough to make a difference with the strong flickering at the top of the frame will cause ghosting in the rest of the picture when there is motion.

I think it's possible to correct the colors line by line by comparing it with other lines (spatial or temporal comparison).

I don't. At least not in the general case -- there's no way of knowing what the colors should be. You might be able to do it in specific shots.

Is there any ready script or software to achieve this or is it necessary to write a custom procedure for that?
After fixing 90 % of the colors this way, a temporalsoften() or spatialsoften() should do the rest...

Not that I know of.

[mathmax]

I don't. At least not in the general case -- there's no way of knowing what the colors should be. You might be able to do it in specific shots.

I think about two different techniques :

- if some of the lines are intact at the top, you choose the x position where the colors are the most saturated and you try to find the y positions where the colors are not green or red above a threshold. You start with a high threshold and you reduce it until the remaining lines have homogeneous colors. Then you take the average colors of these lines as the right colors.

- if all or almost all the lines are affected, you take the an area just under the bad top area. Maybe you can exclude some elements with strong colors inside this area. Then you take the average color of this area as the right color.

Of course there are ways to improve these ideas.. I just think them in the broad outlines...

[mathmax]

ok I wrote a short program to detect the good lines. It works pretty well.
Now I would like to correct the bad line according to the colors of the good lines...
How can I change the R, G, B values of the bad lines knowing the R, G, B value of the closest good line?