Any tips on correcting "incorrect" white balance on old 8mm tape?

[tedkunich]

Finally getting around to coverting 8mm film and 8mm tape of the family Holidays to digital format. Starting with the tapes first and found that there are a few that the camcorder was not properly adjusted for white balance - going back and forth between incandesant and florecent lighting... some scenes are really blue, others are green tinged... Anyone have any pointers as to go about correcting these? I've tried tweak and coloryuv, but as have not had any luck - actually, I have no clue how to get there from here! Source is DV AVI.


Thanks

T

[rfmmars]

First you will need to get the DV.avi footage into Virtualdub. From there you will need the following plug-ins, RGB+, RGB gamma, Auto Levels with contast, Video Warmer IQ, Black Level IQ, MSU Deflicker, HotSpot, and some time on you hands.

If you can't find them drop me a e-mail at WWW.photorecall.net and I will attach plus several VCF filter chains.

richard

[tedkunich]

Originally posted by rfmmars
First you will need to get the DV.avi footage into Virtualdub. From there you will need the following plug-ins, RGB+, RGB gamma, Auto Levels with contast, Video Warmer IQ, Black Level IQ, MSU Deflicker, HotSpot, and some time on you hands.

If you can't find them drop me a e-mail at WWW.photorecall.net and I will attach plus several VCF filter chains.

richard

Richard, are these VD plugins or Avisynth? I never use VD plugins - is there a repository like the warpenterprises for avisynth?

My biggest problem is not knowing what to tweak given an input - on a scene that is obviouly blue tinged, if I lower the blue channel (working in RGB space) my video turns green... I have no clue what gamma is used for... are there any writeups that give a little more insite as to what I want to do?

I would appreciate anything you have to offer by the way of filter chains. It would be very usefull as a starting point.

my email address is: first name at last name dot com ;)



Thanks

Ted

[rfmmars]

Ted.......... the RGB+ is some like a setup board for a color picture tube in a tv set allowing you to set each color as for bright areas and for dark areas as well. The RGB gamma is just that allowing non-linera curves for each channel. The 2 IQ filters let you change what I would call the color demodulation angle allowing for skin tone restoration.

Since reels of film vary I have not found any automactic filter that does a perfect job, but some times they do come very close.

I will get it all together for you in a couple of days.

These are VD filters and no there is not one place to find them all, I not sure I have them all now, but I am close.

richard

[Fizick]

TweakColor filter by trevlac:

http://forum.doom9.org/showthread.php?s=&threadid=74334

http://forum.doom9.org/showthread.php?s=&threadid=77196

[Mug Funky]

what i'd do is grab a frame, take it into photoshop and apply curves to each channel - not only do gains need adjusting for white balance, but white points and black points, etc. using curves to get a good picture, click the pencil button to make the curves a manually drawn line (rather than a spline with anchors), then save the curve as a .amp file.

the .amp file can be used with RGBlut that comes with masktools in avisynth.

the deflickering and stuff you'll probably still need virtualdub plugs for though.

[tedkunich]

Originally posted by Mug Funky
what i'd do is grab a frame, take it into photoshop and apply curves to each channel - not only do gains need adjusting for white balance, but white points and black points, etc. using curves to get a good picture, click the pencil button to make the curves a manually drawn line (rather than a spline with anchors), then save the curve as a .amp file.

the .amp file can be used with RGBlut that comes with masktools in avisynth.

the deflickering and stuff you'll probably still need virtualdub plugs for though.


I'll give that a try... have never really played with curves and gamma before - any thoughts/guidance as to where to start? Probably will not get to it until after Thanksgiving... lot of work to cram into a shorted work week.... :scared:


T

[tedkunich]

Originally posted by Fizick
TweakColor filter by trevlac:

http://forum.doom9.org/showthread.php?s=&threadid=74334

http://forum.doom9.org/showthread.php?s=&threadid=77196

Thanks Fizick, I have downloaded that back when he released it but I'm not a graphic artist so not knowing what to tweak/adjust bewilders me...

total Off Topic, but I tried out your DePan plugin... very impressive... I'm sure I'll be needing it on a couple of the film reels as some of them make me dizzy watching all of the paning and shaky camera.


T

[Mug Funky]

curves and levels adjustments can take a bit of getting used to (guh, my dad just can't seem to grasp it. when i think i've explained it, an hour later he's like "adrian, how does this levels thing work again?", but i digress).

basically it re-maps the values of the colours in the pic. for example, a simple gain adjustment of multiplying the values by 2 (to get a pic twice as bright) would amount to a level adjustment that involves moving the white point to halfway down the scale...

the Gimp has a levels and curves adjustment that works the same as photoshop's (i'm not sure if it saves to the same format though), if you want something that's free.

gamma is a bit different - hard to explain, but it amounts to changing brightness/contrast without using simple gain+offset like levels does (ie. out = in * gain + offset). it will move the mid-point in the scale, and can be adjusted by moving the middle arrow in photoshop's levels.

curves is a bit like gamma, but more versatile - it allows you to control the shape of the remapping curve used.

eek, would somebody else like to explain this? i can't find good words right now :( all i can say is play with it and you'll get the hang of it.

remember you'll need to do each colour channel separately to get a good colour balance - otherwise you're just changing brightness and contrast, rather than colours.

[CraigBjorn]

Ok, I use the gimp, and for curves the best tecnique that I've found is to use the color picking tool, and find a color that should be either white or gray.. click on it and find the color values it gives you... lets say it says Red is 155 Green is 123 and Blue is 157 ... since this should be some form of gray.. those color values should all be the same (grey is made when all three color values are the same), it looks like the green is abit low, making everything else a bit purple.. to fix this you would open up the curves dialog, at the top click down to green . You should say a very streait line.. and if you put your curser over the screen on the line you will see that the x and y are equal. X is the color going in and y is the color going out... right now the color coming in is exactly the same as the color going out... you want to change this on the green... you want 123 on the green to be something like 156 or there abouts so you'd click on the line where x=123 and slide it up to 156. TADA you're done... you'd probably want to do this with some more points.. get some dark points some mids etc. and you'll probably have to change more than one channel....

If you still don't get it after that go to

Grokking The Gimp (http://gimp-savvy.com/BOOK/node61.html#SECTION001421000000000000000)
the same tecnique can be applied to photoshop or any other photo editor...

The only thing I don't know is how to take a gimp output file and and convert it to a photoshop .amp file... they're structure is about the same... but not exactly.... ne ideas?

[MrTVideo]

I think that this topic should be added to best of board or equivelent. I have learnt a valuable lesson. I have PSP 7 hope that can do it. Photoshop is a bit rich for my blood though.

[Mug Funky]

hmm. i wonder if we all supply manao with examples of other photo-editor's curves formats, would he add support for them into masktools? maybe this is asking a bit much... he's already given the avs community a very large amount.

[CraigBjorn]

Man, if I had time I'd do it myself... the gimp's set up is pretty simple... here's some examples for anyone who has the time to tackle it


This is a sample of an unchanged curves file... the top line is for value, the second for red, the third for green, the forth for blue, and the last for alpha

# GIMP Curves File
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255

This is an example where the input of black as 20 is set to zero... (The equivilant of Levels(20, 1, 255, 0, 255)
# GIMP Curves File
-1 0 20 0 -1 0 -1 0 -1 0 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255

This is an example where the white is shifted to 235... (equivilant of Levels(0, 1, 235, 0, 255)

# GIMP Curves File
0 0 -1 0 -1 0 -1 0 -1 0 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 -1 255 235 255 -1 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255

And another example which is a combination of the two perevious (equivilant of Levels(20, 1, 235, 0, 255)

# GIMP Curves File
-1 0 20 0 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 235 255 -1 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255

Finally... this is the same thing as the last one, except that I pushed values of 128 to 200 (read my last post for an explanation of this)

# GIMP Curves File
-1 0 20 0 -1 0 -1 0 -1 0 -1 0 -1 -1 -1 -1 128 200 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 -1 255 235 255 -1 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255
0 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 255 255



Hopefully this helps somebody... I still don't fully understand it, but it looks like the x value is to the left and the y value is to the right and it does this for all the points... the only problem I can see is how to graph 5 lines and create a look up table from that... ne ideas?

[Mug Funky]

hmm... when you switch it to "pencil" mode (the button's down the bottom right somewhere) does it output a lookup table with 1 value per colour level? photoshop's .amp files are like that, and these are the ones that rgblut reads.

[edit] never mind, looks like it uses the same format for both. it must do some kind of interpolation.