Reverse the way image color affects colors

Question

Hello

Lets say i'm building a 2048 type game using the NGUI (i know that might be a mistake) so i made images corresponding to different number tiles (and i have to use images, school work) so the original image looks like this alt text and when changing the color of the image in the unity editor i get this so the darker the color is, the less effect the image color has i'm guessing ill need to use a shader here and i did find a thread about the overlay shader however that did not work at all. i want to be able to effect the black parts and not the white parts (so like a reverse of what is currently happening)

Answer 1

In the end i used a shader from another thread

 Shader "Custom/OverlayBlend"
 {
     Properties
     {
         _MainTex ("Texture", 2D) = "" {}
     }
    
     SubShader
     {
         Tags
         {
             "Queue" = "Transparent"
             "RenderType" = "Transparent"
         }
        
         Lighting Off
         Blend SrcAlpha OneMinusSrcAlpha
        
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma fragmentoption ARB_precision_hint_fastest
            
             #include "UnityCG.cginc"
            
             struct appdata_custom
             {
                 float4 vertex : POSITION;
                 fixed2 uv : TEXCOORD0;
                 float4 color : COLOR;
             };
            
             struct v2f
             {
                 float4 vertex : POSITION;
                 fixed2 uv : TEXCOORD0;
                 float4 color : COLOR;
             };
            
             sampler2D _MainTex;
             fixed4 _MainTex_ST;
            
             v2f vert (appdata_custom v)
             {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);
                 o.uv = TRANSFORM_TEX(v.uv,_MainTex);
                 o.color = v.color;
                 return o;
             }          
            
             fixed4 frag (v2f i) : COLOR
             {
                 fixed4 diffuse = tex2D(_MainTex, i.uv);
                 fixed luminance =  dot(diffuse, fixed4(0.2126, 0.7152, 0.0722, 0));
                 fixed oldAlpha = diffuse.a;
                
                 if (luminance < 0.5)
                     diffuse *= 2 * i.color;
                 else
                     diffuse = 1-2*(1-diffuse)*(1-i.color);
                
                 diffuse.a  = oldAlpha * i.color.a;
                 return diffuse;
             }
             ENDCG
         }
     }
     Fallback off
 }

the result looks quite nice. simplifying the shader's algorithm- how much "color" you put on a pixel is in inverse correlation to how white (or luminescent) it is

Reverse the way image color affects colors

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