How to remove complete green background of video

Hi,
I am developing an app with unity. In that, I want to remove the green background of the video and should make transparent. I have used shader script to remove the background. It's removing background but still, it's not clearing border of the content.

I used this script please tell any correction in this or tell me any other best way to do that

Code (CSharp):

1. Shader "Custom/ChromaKey" {
2. Properties {
3.   _MainTex ("Base (RGB)", 2D) = "white" {}
4.   _AlphaValue ("Alpha Value", Range(0.0,1.0)) = 1.0
5. }
6. SubShader {
7.   Tags { "Queue"="Transparent" "RenderType"="Transparent" }
8.   LOD 800
9.   CGPROGRAM
10.   #pragma surface surf Lambert alpha
11.   sampler2D _MainTex;
12.   float _AlphaValue;
13.   struct Input {
14.    float2 uv_MainTex;
15.   };
16.   void surf (Input IN, inout SurfaceOutput o) {
17.    half4 c = tex2D (_MainTex, IN.uv_MainTex);
18.    o.Emission = c.rgb;
19.    // Green screen level - leaves minor green glow
20.    if (c.g == 1) {
21.        o.Alpha = 0.0;
22.    }else{
23.        o.Alpha = c.a;
24.    }
25.   }
26.   ENDCG
27. }
28. FallBack "Diffuse"
29. }

 

Using c.g == 1 to determine green is pretty ridiculous. It for one thing considers pure yellow or white to also be green. But #00FE00 would be considered not green at all.

What you want is to specify a reference color and falloff. And fade transparency based on that:

Code (csharp):

1.  
2. half alpha_pass = saturate(distance(c.rgb, _AlphaColor) / _AlphaFalloff); // Amount of not matching the color
3. c.a *= alpha_pass; // Adjustment of alpha
4. half alpha_pass_limit = max(0.1, alpha_pass); // Prevents a division by zero
5. c.rgb = (c.rgb - (1 - alpha_pass_limit) * _AlphaColor) / alpha_pass_limit; // Adjustment of color
6.  

Where _AlphaColor is a half3 color input for the color to remove and _AlphaFalloff a half input for the range to remove. I just made up those last two lines to adjust the color, but if my math is right, it should work. Note that this is still a pretty simple approach to a green screen shader, but it should be half decent.

 

Hi jvo3dc,

Where should I add this code in my script.

 

Between half4 c=.... and o.Emission=....

The whole if below that should then be replaced by just:

Code (csharp):

1.  
2. o.Alpha = c.a;
3.  

 

Hi jvo3dc,

I used your code but now video not even showing. Fully came with the white screen only audio is coming. I used your code like this please tell any wrong on this

Code (CSharp):

1. Shader "Custom/ChromaKey" {
2.  
3. Properties {
4.   _MainTex ("Base (RGB)", 2D) = "white" {}
5.   _AlphaValue ("Alpha Value", Range(0.0,1.0)) = 1.0
6.   _Threshold ("Threshold Value", Range(0.0,1.0)) = 1.0
7. }
8.  
9. SubShader {
10.   Tags { "Queue"="Transparent" "RenderType"="Transparent" }
11.   LOD 800
12.  
13.   CGPROGRAM
14.   #pragma surface surf Lambert alpha
15.   sampler2D _MainTex;
16.   float _AlphaValue;
17.   struct Input {
18.    float2 uv_MainTex;
19.   };
20.   void surf (Input IN, inout SurfaceOutput o) {
21.    half4 c = tex2D (_MainTex, IN.uv_MainTex);
22.    o.Emission = c.rgb;
23.    
24.    // Green screen level - leaves minor green glow
25.    //c.g >= 0.39215686274f && c.r <= 0.0f && c.b <= 0.0f && _AlphaValue == 0.0
26.    if (c.g == 1) {
27.        o.Alpha = 0.0;
28.        //o.glow = 1;
29.    }else{
30.        //o.Alpha = c.a;
31.         half alpha_pass = saturate(distance(c.rgb, _AlphaColor) / _AlphaFalloff); // Amount of not matching the color
32.         c.a *= alpha_pass; // Adjustment of alpha
33.         half alpha_pass_limit = max(0.1, alpha_pass); // Prevents a division by zero
34.         c.rgb = (c.rgb - (1 - alpha_pass_limit) * _AlphaColor) / alpha_pass_limit; // Adjustment of color
35.    }
36.   }
37.   ENDCG
38. }
39. FallBack "Diffuse"
40. }

 

Code (csharp):

1.  
2. void surf (Input IN, inout SurfaceOutput o) {
3.    half4 c = tex2D (_MainTex, IN.uv_MainTex);
4.    half alpha_pass = saturate(distance(c.rgb, _AlphaColor) / _AlphaFalloff); // Amount of not matching the color
5.    c.a *= alpha_pass; // Adjustment of alpha
6.    half alpha_pass_limit = max(0.1, alpha_pass); // Prevents a division by zero
7.    c.rgb = (c.rgb - (1 - alpha_pass_limit) * _AlphaColor) / alpha_pass_limit; // Adjustment of color
8.    o.Emission = c.rgb;
9.    o.Alpha = c.a;
10. }
11.  

 

Tried this also but same white screen only coming. If there is no if conditio then how can I check my green color to remove.

 

Well, you're doing something else wrong, since your code before just said:

Code (csharp):

1.  
2. half4 c = tex2D (_MainTex, IN.uv_MainTex);
3. o.Emission = c.rgb;
4.  

After you've fixed whatever is going wrong, what are your values of _AlphaColor and _AlphaFallof?

Finally, there is no reason to use an if to replace a color with transparency. It's like fuzzy logic.

 

I want remove r= 0, g=255 , b=0 This rgb value I want to remove. How to give value for that.

 

Set _AlphaColor to 0, 1, 0 and then play with the _AlphaFalloff value. (Between 0 and 1 roughly)

 

@jvo3dc
I have tried Like this

Code (CSharp):

1.  half4 c = tex2D (_MainTex, IN.uv_MainTex);
2.    half alpha_pass = saturate(distance(c.rgb, 0, 1, 0) / 1); // Amount of not matching the color

And this

Code (CSharp):

1. half4 c = tex2D (_MainTex, IN.uv_MainTex);
2.    half alpha_pass = saturate(distance(0, 1, 0, 0) / 1); // Amount of not matching the color

But I am getting following error at compile time for both

Shader error in 'Custom/ChromaKeyWhite': unable to find compatible overloaded function "distance(half3, int, int, int)" unable to find compatible overloaded function "saturate(error)" at line 39 (on d3d9)

 

Well, distance takes 2 parameters of the same vector type and not 4 parameters. So
distance (c.rgb, half3 (0.0, 1.0, 0.0))

 

I managed to get it working but my model shows white instead of its normal albedo colors.