change one specific color to another

[ryberg]

I know there are several ways to do this, but I would like to create an action like the "Tint Blue" brush and "All Blue" action.

I've looked into the code of these actions but I can't get my head around it. Stuff like this doesn't make much sense to me:

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tv_cmd Heads tv_pixelmatrix 0 0 0 0 0   0 0 0 0.588 0   0 0 0 1 0   0 0 0 1 0

I'd like it to work like the "All Blue" action above, only it just turns red into blue and not black, so red becomes blue and black stays black

[Eric Scholl]

I know there are several ways to do this, but I would like to create an action like the "Tint Blue" brush and "All Blue" action.

I've looked into the code of these actions but I can't get my head around it. Stuff like this doesn't make much sense to me:

Code: Select all

tv_cmd Heads tv_pixelmatrix 0 0 0 0 0   0 0 0 0.588 0   0 0 0 1 0   0 0 0 1 0

I'd like it to work like the "All Blue" action above, only it just turns red into blue and not black, so red becomes blue and black stays black

This should be the correct one ( Red to Blue ):

Code: Select all

tv_cmd Heads tv_pixelmatrix 0 0 0 0 0   0 1 0 0 0   1 0 1 0 0   0 0 0 1 0

[ryberg]

Yeah, that is exactly what I was looking for, almost
I just want it to change into the light sketching blue rather than the dark one. Sorry for being difficult.

Also, how do you read RGBA values out of those codes, are there any available simple explanation on this anywhere? Just being curious and trying to understand these codes so I won't need to ask for help every time I dive into it.

Thanks a lot Eric.

[ryberg]

I'm looking at this and trying to understand it. I'd love if it came with a text explaining it.

http://wiki.tvpaint.fr/index.php?title=Tv_PixelMatrix

I get that, 0 represent turned off and 1 is on since the value is multiplied with 255 in order to get the rgba value, but what is k, black? and what are capital R, G, B, A?

[Eric Scholl]

Here is how it basically works :

you have 4 groups : R G B A

In each group, you have 5 numbers : r g b a k

The 4 firsts numbers are factors which determines how much the channel of the current color will impact on the final channel.

For example, if in my pixel I want to use the value of the blue channel as the value of the red, I'll do this in the first group (R):

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    R
r g b a k
0 0 1 0 0 

If I want a channel to keep the same value, I'll do this :

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    R
r g b a k
1 0 0 0 0

So in my example, if I only want to change the red value, I need to do this:

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    R              G              B             A
r g b a k      r g b a k      r g b a k     r g b a k
0 0 1 0 0      0 1 0 0 0      0 0 1 0 0     0 0 0 1 0

The 'k' value is constant which is added to the result.
Second example, let's say I have these color values :

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R = 255    G = 100   B = 255    A = 255

I want the red to have the green value + 50, so I do this :

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    R
r g b a k
0 1 0 0 50

And if I want the red to have the green value - 50, I do this :

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    R
r g b a k
0 1 0 0 -50

Here's my complete sequence for the second example :

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    R            G              B             A
r g b a k    r g b a k      r g b a k     r g b a k
0 1 0 0 50   0 1 0 0 0      0 0 1 0 0     0 0 0 1 0

The result will be :

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R = 150    G = 100   B = 255    A = 255

I hope this will help you, I know it's complicated.

[ryberg]

thank you so much! For the first time, it makes sense. Now I need to test it to see if I got it but you really explained it quite well.

[Eric Scholl]

Thank you

One more things, If you want to change a color to another one, it will work with basic colors, but you cannot do it with a precise color.

[Mads Juul]

Great explanation Eric. I put it into the wiki.
-Mads

[Eric Scholl]

Great explanation Eric. I put it into the wiki.
-Mads

Thank you Mads
I thought no one would understand ...

[Mads Juul]

[ryberg]

well, I need to practise it a lot more cause none of my scripts I just tried have worked as I thought.

[ryberg]

after your thorough explanation, I thought I got it but as I try it out it makes less and less sense. I am completely lost here.

What I am trying to do is to turn red into light blue:

source (red):

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R = 255	G = 0		B = 0		A = 255

goal (light blue):

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R = 0	G = 150	B = 255	A = 255

So I am thinking this:

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0 0.588 1 0 0   0 1 0 0 0   0 0 1 0 0   0 0 0 1 0

but that create weird results.

Also, when a value is entered as 0.something decimals, I assume it equals 0.588*255 in order to return the right 255 level value of the rgba chart, am I right?

I noticed in the erase actions that negative values are present like -1, I assume this is a way to erase a color but then I ask myself what 0 is if it takes -1 to erase something. Is 0 null? does it represent unchanged values.

I am absolutely confused.

[ZigOtto]

try this :

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tv_cmd Heads tv_pixelmatrix 0 0 0 0 0   0.588 1 0 0 0   1 0 1 0 0   0 0 0 1 0

I think it should turn the Red lines into light-Blue.

[Eric Scholl]

So I am thinking this:

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0 0.588 1 0 0   0 1 0 0 0   0 0 1 0 0   0 0 0 1 0

This is not working because you applied your modification on the Red Channel (the first 5 numbers group).

You should do this :

First group ( R ), erase the red :

0 0 0 0 0

Second group ( G ), use the value of the red color with a ratio ( 255->150) but keep the green value :

0.588 1 0 0 0

First group ( B ), use the red value and keep the blue value :

1 0 1 0 0

Last group ( A ), just keep the Alpha value :

0 0 0 1 0

So you do this :

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tv_cmd Heads tv_pixelmatrix 0 0 0 0 0   0.588 1 0 0 0   1 0 1 0 0   0 0 0 1 0

[ryberg]

thank you guys for being so patient with me, I guess I got confused with source and result. It's really nice to get this covered, I've been wondering about this for a long time.

This takes some practise.

First, I thought I needed to type in values in the first group (R) in order to change that into green, but I see it simply needs to be erased.

So in the second group (B), the change from red to light blue (partial green, aka green), happens when I put in a value in "r" the first number that represents red. If I would leave the value 1, it will turn red into full green (combined with a full blue the result will be dark blue (r: 0 g: 255 b: 255)).
And I need to put in 1 in "b" the third number representing blue in order to maintain blue colors in whatever this action is applied to.

Third group is basically the same as Second group, only "r" value needs to be turned into full blue hence 1.


Am I slowly getting this now?