diff --git a/ImGuiVisitor.cpp b/ImGuiVisitor.cpp
index cced38d..80c8b6e 100644
--- a/ImGuiVisitor.cpp
+++ b/ImGuiVisitor.cpp
@@ -187,16 +187,15 @@ void ImGuiVisitor::visit(ImageProcessingShader &n)
 {
     ImGui::PushID(n.id());
 
-    if (ImGuiToolkit::ButtonIcon(4, 0)) n.gamma = glm::vec4(1.f, 1.f, 1.f, 1.f);
-    float g[3] = { n.gamma.x, n.gamma.y, n.gamma.z};
+    if (ImGuiToolkit::ButtonIcon(6, 2)) n.gamma = glm::vec4(1.f, 1.f, 1.f, 1.f);
     ImGui::SameLine(0, 10);
+    ImGui::ColorEdit3("GammaColor", glm::value_ptr(n.gamma), ImGuiColorEditFlags_NoInputs | ImGuiColorEditFlags_NoLabel) ;
+    ImGui::SameLine(0, 5);
     ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
-    if ( ImGui::SliderFloat3("RGB", g, 1.0, 10.0) )
-    {
-        n.gamma.x = g[0];
-        n.gamma.y = g[1];
-        n.gamma.z = g[2];
-    }
+    ImGui::SliderFloat("Gamma", &n.gamma.w, 0.5f, 10.f, "%.2f", 2.f);
+
+//    ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
+//    ImGui::SliderFloat4("Levels", glm::value_ptr(n.levels), 0.0, 1.0);
 
     if (ImGuiToolkit::ButtonIcon(4, 1)) {
         n.brightness = 0.f;
@@ -216,7 +215,6 @@ void ImGuiVisitor::visit(ImageProcessingShader &n)
     ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
     ImGui::SliderFloat("Saturation", &n.saturation, -1.0, 1.0);
 
-
     if (ImGuiToolkit::ButtonIcon(12, 4)) n.hueshift = 0.f;
     ImGui::SameLine(0, 10);
     ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
@@ -248,7 +246,7 @@ void ImGuiVisitor::visit(ImageProcessingShader &n)
     ImGui::Combo("Invert", &n.invert, "None\0Invert Color\0Invert Luminance\0");
 
     if (ImGuiToolkit::ButtonIcon(13, 4)) {
-        n.chromakey = glm::vec4(0.f, 1.f, 0.f, 1.f);
+        n.chromakey = glm::vec4(0.f, 0.8f, 0.f, 1.f);
         n.chromadelta = 0.f;
     }
     ImGui::SameLine(0, 10);
@@ -295,9 +293,9 @@ void ImGuiVisitor::visit (MediaSource& s)
 void ImGuiVisitor::visit (SessionSource& s)
 {
     ImGui::Text("Session File");
-    if ( ImGui::Button("Make Current", ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
+    if ( ImGui::Button( ICON_FA_FILE_UPLOAD " Make Current", ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
         Mixer::manager().set( s.detach() );
-    if ( ImGui::Button( ICON_FA_FILE_IMPORT " Merge", ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
+    if ( ImGui::Button( ICON_FA_FILE_EXPORT " Import", ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
         Mixer::manager().merge( s.detach() );
 
     ImGuiToolkit::ButtonOpenUrl( SystemToolkit::path_filename(s.path()).c_str(), ImVec2(IMGUI_RIGHT_ALIGN, 0) );
diff --git a/ImageProcessingShader.cpp b/ImageProcessingShader.cpp
index 5213720..11f894f 100644
--- a/ImageProcessingShader.cpp
+++ b/ImageProcessingShader.cpp
@@ -59,11 +59,31 @@ void ImageProcessingShader::reset()
     filterid = 0;
     gamma = glm::vec4(1.f, 1.f, 1.f, 1.f);
     levels = glm::vec4(0.f, 1.f, 0.f, 1.f);
-    chromakey = glm::vec4(0.f, 1.f, 0.f, 0.f);
+    chromakey = glm::vec4(0.f, 0.8f, 0.f, 0.f);
     chromadelta = 0.f;
 
 }
 
+void ImageProcessingShader::operator = (const ImageProcessingShader &S )
+{
+    Shader::operator =(S);
+
+    brightness = S.brightness;
+    contrast = S.contrast;
+    saturation = S.saturation;
+    hueshift = S.hueshift;
+    threshold = S.threshold;
+    lumakey = S.lumakey;
+    nbColors = S.nbColors;
+    invert = S.invert;
+    filterid = S.filterid;
+    gamma = S.gamma;
+    levels = S.levels;
+    chromakey = S.chromakey;
+    chromadelta = S.chromadelta;
+}
+
+
 void ImageProcessingShader::accept(Visitor& v) {
 //    Shader::accept(v);
     v.visit(*this);
diff --git a/ImageProcessingShader.h b/ImageProcessingShader.h
index 468aac8..c918114 100644
--- a/ImageProcessingShader.h
+++ b/ImageProcessingShader.h
@@ -17,6 +17,8 @@ public:
     void reset() override;
     void accept(Visitor& v) override;
 
+    void operator = (const ImageProcessingShader &S);
+
 //    // textures resolution
 //    glm::vec3 iChannelResolution[1];
 
diff --git a/ImageShader.cpp b/ImageShader.cpp
index 7abff29..4da74f1 100644
--- a/ImageShader.cpp
+++ b/ImageShader.cpp
@@ -37,15 +37,20 @@ void ImageShader::use()
     program_->setUniform("stipple", stipple);
 
     glActiveTexture(GL_TEXTURE1);
-    if ( mask < 9 )
+    if ( mask < 9 ) {
         glBindTexture(GL_TEXTURE_2D, mask_presets[mask]);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    }
     else
         glBindTexture(GL_TEXTURE_2D, custom_textureindex);
     glActiveTexture(GL_TEXTURE0);
 
 }
 
-
 void ImageShader::reset()
 {
     Shader::reset();
@@ -57,6 +62,16 @@ void ImageShader::reset()
     stipple = 0.f;
 }
 
+void ImageShader::operator = (const ImageShader &S )
+{
+    Shader::operator =(S);
+
+    mask = S.mask;
+    custom_textureindex = S.custom_textureindex;
+    stipple = S.stipple;
+}
+
+
 void ImageShader::accept(Visitor& v) {
     Shader::accept(v);
     v.visit(*this);
diff --git a/ImageShader.h b/ImageShader.h
index 97111e9..49faaba 100644
--- a/ImageShader.h
+++ b/ImageShader.h
@@ -22,6 +22,7 @@ public:
     void reset() override;
     void accept(Visitor& v) override;
 
+    void operator = (const ImageShader &S);
 
     uint mask;
     uint custom_textureindex;
diff --git a/Shader.cpp b/Shader.cpp
index bdabd16..a0a70e7 100644
--- a/Shader.cpp
+++ b/Shader.cpp
@@ -180,6 +180,13 @@ Shader::Shader() : blending(BLEND_OPACITY)
     reset();
 }
 
+
+void Shader::operator = (const Shader &S )
+{
+    color = S.color;
+    blending = S.blending;
+}
+
 void Shader::accept(Visitor& v) {
     v.visit(*this);
 }
diff --git a/Shader.h b/Shader.h
index 9f6a57e..07a167d 100644
--- a/Shader.h
+++ b/Shader.h
@@ -41,7 +41,6 @@ class Shader
 
 public:
     Shader();
-//    virtual ~Shader() {}
 
     // unique identifyer generated at instanciation
     inline int id () const { return id_; }
@@ -50,6 +49,8 @@ public:
     virtual void reset();
     virtual void accept(Visitor& v);
 
+    void operator = (const Shader &D );
+
     glm::mat4 projection;
     glm::mat4 modelview;
     glm::vec4 color;
diff --git a/UserInterfaceManager.cpp b/UserInterfaceManager.cpp
index a4ddf35..53d8fbd 100644
--- a/UserInterfaceManager.cpp
+++ b/UserInterfaceManager.cpp
@@ -1128,9 +1128,9 @@ void Navigator::RenderSourcePannel(Source *s)
         // delete button
         ImGui::Text(" ");
         // Action on source
-        if ( ImGui::Button("Clone", ImVec2(ImGui::GetContentRegionAvail().x, 0)) )
+        if ( ImGui::Button( ICON_FA_SHARE_SQUARE " Clone", ImVec2(ImGui::GetContentRegionAvail().x, 0)) )
             Mixer::manager().cloneCurrentSource();
-        if ( ImGui::Button("Delete", ImVec2(ImGui::GetContentRegionAvail().x, 0)) ) {
+        if ( ImGui::Button( ICON_FA_BACKSPACE " Delete", ImVec2(ImGui::GetContentRegionAvail().x, 0)) ) {
             Mixer::manager().deleteSource(s);
         }
     }
diff --git a/rsc/shaders/image.fs b/rsc/shaders/image.fs
index b54e692..3e2e2ff 100644
--- a/rsc/shaders/image.fs
+++ b/rsc/shaders/image.fs
@@ -23,7 +23,7 @@ void main()
     float maskIntensity = (maskColor.r + maskColor.g + maskColor.b) / 3.0;
 
     float A = textureColor.a * vertexColor.a * color.a * maskIntensity;
-    A -= stipple * ( int(gl_FragCoord.x + gl_FragCoord.y) % 2 > 0 ? 0.0 : 9.0 );
+    A -= stipple * ( int(gl_FragCoord.x + gl_FragCoord.y) % 2 > 0 ? 0.05 : 0.95 );
 
     // output RGBA
     FragColor = vec4(RGB, clamp(A, 0.0, 1.0) );
diff --git a/rsc/shaders/imageprocessing.fs b/rsc/shaders/imageprocessing.fs
index f2dbe3b..15e22d3 100644
--- a/rsc/shaders/imageprocessing.fs
+++ b/rsc/shaders/imageprocessing.fs
@@ -326,9 +326,8 @@ void main(void)
     // chromakey
     alpha -= mix( 0.0, 1.0 - alphachromakey( transformedRGB, chromakey.rgb, chromadelta), float(chromadelta > 0.0001) );
 
-    // color transformation
+    // brightness and contrast transformation
     transformedRGB = mix(vec3(0.62), transformedRGB, contrast + 1.0) + brightness;
-    transformedRGB = LevelsControl(transformedRGB, levels.x, gamma.rgb * gamma.a, levels.y, levels.z, levels.w);
 
     // RGB invert
     transformedRGB = vec3(float(invert==1)) + ( transformedRGB * vec3(1.0 - 2.0 * float(invert==1)) );
@@ -352,11 +351,14 @@ void main(void)
     alpha -= mix( 0.0, step( transformedHSL.z, lumakey ), float(lumakey > EPSILON));
 
     // level threshold
-    transformedHSL = mix( transformedHSL, vec3(0.0, 0.0, step( transformedHSL.z, threshold )), float(threshold > EPSILON));
+    transformedHSL = mix( transformedHSL, vec3(0.0, 0.0, 0.95 - step( transformedHSL.z, threshold )), float(threshold > EPSILON));
 
     // after operations on HSL, convert back to RGB
     transformedRGB = HSV2RGB(transformedHSL);
 
+    // apply gamma correction
+    transformedRGB = LevelsControl(transformedRGB, levels.x, gamma.rgb * gamma.a, levels.y, levels.z, levels.w);
+
     // apply base color and alpha for final fragment color
     FragColor = vec4(transformedRGB * vertexColor.rgb * color.rgb, clamp(alpha, 0.0, 1.0) );