Finalizing implementation of chroma and luma key Transparency filters

ImGuiVisitor.cpp

@@ -922,6 +922,22 @@ void ImGuiVisitor::visit (AlphaFilter& f)
 
     if ( m == AlphaFilter::ALPHA_CHROMAKEY || m == AlphaFilter::ALPHA_LUMAKEY)
     {
+        float t = filter_parameters["Threshold"];
+        if (ImGuiToolkit::IconButton(13, 14)) {
+            t = 0.f;
+            f.setProgramParameter("Threshold", t);
+        }
+        ImGui::SameLine(0, IMGUI_SAME_LINE);
+        ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
+        if (ImGui::SliderFloat( "Threshold", &t, 0.f, 1.f, "%.2f")) {
+            f.setProgramParameter("Threshold", t);
+        }
+        if (ImGui::IsItemDeactivatedAfterEdit()) {
+            oss << AlphaFilter::operation_label[ f.operation() ];
+            oss << " : " << "Threshold" << " " << std::setprecision(3) << t;
+            Action::manager().store(oss.str());
+        }
+
         float v = filter_parameters["Tolerance"];
         if (ImGuiToolkit::IconButton(13, 14)) {
             v = 0.f;

ImageFilter.cpp

@@ -477,7 +477,7 @@ void ImageFilter::setProgramParameter(const std::string &p, float value)
 ////////////////////////////////////////
 
 const char* ResampleFilter::factor_label[ResampleFilter::RESAMPLE_INVALID] = {
-    "Double x2", "Half   1/2", "Quarter 1/4"
+    "Double resolution", "Half resolution", "Quarter resolution"
 };
 
 std::vector< FilteringProgram > ResampleFilter::programs_ = {
@@ -781,8 +781,8 @@ const char* AlphaFilter::operation_label[AlphaFilter::ALPHA_INVALID] = {
 };
 
 std::vector< FilteringProgram > AlphaFilter::programs_ = {
-    FilteringProgram("Chromakey","shaders/filters/chromakey.glsl",   "",  { { "Red", 0.0}, { "Green", 1.0}, { "Blue", 0.0}, { "Tolerance", 1.0} }),
+    FilteringProgram("Chromakey","shaders/filters/chromakey.glsl",   "",  { { "Red", 0.0}, { "Green", 1.0}, { "Blue", 0.0}, { "Threshold", 0.5}, { "Tolerance", 0.5} }),
-    FilteringProgram("Lumakey",  "shaders/filters/lumakey.glsl",     "",  { { "Tolerance", 0.5} }),
+    FilteringProgram("Lumakey",  "shaders/filters/lumakey.glsl",     "",  { { "Threshold", 0.5}, { "Tolerance", 0.5} } ),
     FilteringProgram("coloralpha","shaders/filters/coloralpha.glsl", "",  { { "Red", 0.0}, { "Green", 1.0}, { "Blue", 0.0} })
 };
 

rsc/shaders/filters/chromakey.glsl

@@ -13,6 +13,7 @@ green-ish look or are a bit transparent (hard to catch with a lot of movement)
 uniform float Red;
 uniform float Green;
 uniform float Blue;
+uniform float Threshold;
 uniform float Tolerance;
 
 //conversion between rgb and YUV
@@ -22,19 +23,16 @@ mat4 RGBtoYUV = mat4(0.257,  0.439, -0.148, 0.0,
                      0.0625, 0.500,  0.500, 1.0 );
 
 // color to be removed
-vec4 chromaKey = vec4(Red, Green, Blue, 1);
+vec4 chromaKey = vec4(Red, Green, Blue, 1.);
-
-//range is used to decide the amount of color to be used from either foreground or background
-//if the current distance from pixel color to chromaKey is smaller then maskRange.x we use background,
-//if the current distance from pixel color to chromaKey is bigger then maskRange.y we use foreground,
-//else, we blend them
-//playing with this variable will decide how much the foreground and background blend together
-vec2 maskRange = vec2(0.01, Tolerance * 0.5);
 
 //compute color distance in the UV (CbCr, PbPr) plane
-float colorclose(vec3 yuv, vec3 keyYuv, vec2 tol)
+float colordistance(vec3 yuv, vec3 keyYuv, vec2 tol)
 {
-    float tmp = sqrt(pow(keyYuv.g - yuv.g, 2.0) + pow(keyYuv.b - yuv.b, 2.0));
+    // color distance in the UV (CbCr, PbPr) plane
+//    float tmp = sqrt(pow(keyYuv.y - yuv.y, 2.0) + pow(keyYuv.z - yuv.z, 2.0));
+    vec2 dif = yuv.yz - keyYuv.yz;
+    float tmp = sqrt(dot(dif, dif));
+
     if (tmp < tol.x)
         return 0.0;
     else if (tmp < tol.y)
@@ -43,36 +41,20 @@ float colorclose(vec3 yuv, vec3 keyYuv, vec2 tol)
         return 1.0;
 }
 
-float alphachromakey(vec3 color, vec3 colorKey, float delta)
-{
-   // magic values
-   vec2 tol = vec2(0.5, 0.4*delta);
-
-   //convert from RGB to YCvCr/YUV
-   vec4 keyYuv = RGBtoYUV * vec4(colorKey, 1.0);
-   vec4 yuv = RGBtoYUV * vec4(color, 1.0);
-
-   // color distance in the UV (CbCr, PbPr) plane
-   vec2 dif = yuv.yz - keyYuv.yz;
-   float d = sqrt(dot(dif, dif));
-
-   // tolerance clamping
-   return max( (1.0 - step(d, tol.y)), step(tol.x, d) * (d - tol.x) / (tol.y - tol.x));
-}
-
-
-
 void mainImage( out vec4 fragColor, in vec2 fragCoord )
 {
     vec4 texColor0 = texture(iChannel0, fragCoord.xy / iResolution.xy);
 
     //convert from RGB to YCvCr/YUV
-//    vec4 keyYUV = RGBtoYUV * chromaKey;
+    vec4 keyYUV = RGBtoYUV * chromaKey;
-//    vec4 yuv = RGBtoYUV * texColor0;
+    vec4 yuv = RGBtoYUV * texColor0;
-//    float mask = 1.0 - colorclose(yuv.rgb, keyYUV.rgb, maskRange);
-//    fragColor = max(texColor0 - mask * chromaKey, 0.0);
 
-    float A = alphachromakey(texColor0.rgb, chromaKey.rgb, Tolerance);
+    float t = (1. - Tolerance) * 0.2;
+    float mask = 1.0 - colordistance(yuv.rgb, keyYUV.rgb, vec2(t, t + 0.2));
+    vec4 col = max(texColor0 - mask * chromaKey, 0.0);
 
-    fragColor = vec4( texColor0.rgb, A );
+    t = Threshold * Threshold * 0.2;
+    col.a -= 1.0 - colordistance(yuv.rgb, keyYUV.rgb, vec2(t, t + 0.25));
+
+    fragColor = col;
 }

rsc/shaders/filters/lumakey.glsl

@@ -1,3 +1,4 @@
+uniform float Threshold;
 uniform float Tolerance;
 
 
@@ -36,5 +37,5 @@ void mainImage( out vec4 fragColor, in vec2 fragCoord )
     float L = dot(RGB, vec3(0.299, 0.587, 0.114));
 //    float L = lightness( RGB );
 
-    fragColor = vec4( RGB, smoothstep( 0.0, Tolerance, L ) );
+    fragColor = vec4( RGB, smoothstep( Threshold, Threshold + Tolerance * Tolerance, L ) );
 }