Contrast image

Charcoal/Charcoal/Charcoal.cpp

@@ -78,7 +78,6 @@ Charcoal::Charcoal() {
     overlay_->view()->set_view_listener(this);
 }
 
-
 Charcoal::~Charcoal() {
 }
 
@@ -142,6 +141,12 @@ void Charcoal::grayscaleName(const JSObject& thisObject, const JSArgs& args) { /
 }
 
 
+void Charcoal::contrastValue(const JSObject& thisObject, const JSArgs& args) {
+    MessageBoxA(NULL, "Please sit tight, contrasting your book.", "Book Contrasting", MB_OK);   
+
+}
+
+
 void Charcoal::OpenFile(const JSObject& thisObject, const JSArgs& args)
 {
     //dialog box for file select
@@ -199,6 +204,7 @@ void Charcoal::OnDOMReady(ultralight::View* caller,
     global["AddBook"] = BindJSCallback(&Charcoal::OpenFile);
     global["nameToGrayscale"] = BindJSCallback(&Charcoal::grayscaleName);
     global["deleteBook"] = BindJSCallback(&Charcoal::deleteBooks);
+    global["contrastValue"] = BindJSCallback(&Charcoal::contrastValue);
 
     auto scoped_context = context;
 

Charcoal/Charcoal/Charcoal.h

@@ -36,6 +36,7 @@ class Charcoal : public AppListener,
     virtual void deleteBooks(const JSObject& thisObject, const JSArgs& args);
     virtual JSValue printAllBooks(const JSObject& thisObject, const JSArgs& args);
     virtual void grayscaleName(const JSObject& thisObject, const JSArgs& args);
+    virtual void contrastValue(const JSObject& thisObject, const JSArgs& args);
 
     // This is called when the DOM has loaded in one of its frames.
     virtual void OnDOMReady(ultralight::View* caller,

Charcoal/Charcoal/Epub.cpp

@@ -130,6 +130,10 @@ void Epub::grayscaleEpub(PWSTR path) {
             // Grayscale the image
             grayscaleImage(image, width, height);
 
+            // Contrast the image
+            int contrast_value = 1;
+            contrastImage(image, width, height, contrast_value);
+
             std::string base_filename = name.substr(name.find_last_of("/\\") + 1);
             if(fileExt == "jpeg" || fileExt == "jpg")
                 stbi_write_jpg((temp + base_filename).c_str(), width, height, channels, image, 100);
@@ -163,3 +167,20 @@ void Epub::grayscaleImage(unsigned char* imageData, int width, int height) {
         imageData[3 * i + 2] = gray;
     }
 }
+
+void Epub::contrastImage(unsigned char* imageData, int width, int height, int contrast_value) {
+    // Convert RGB image to grayscale
+    for (int i = 0; i < width * height; ++i) {
+        unsigned char gray_value;
+        if (imageData[3 * i] * contrast_value > 255) {
+            gray_value = 255;
+        }
+        else {
+            gray_value = imageData[3 * i] * contrast_value;
+        }
+
+        imageData[3 * i] = gray_value;
+        imageData[3 * i + 1] = gray_value;
+        imageData[3 * i + 2] = gray_value;
+    }
+}

Charcoal/Charcoal/Epub.h

@@ -7,5 +7,6 @@ class Epub : public Library
 		void grayscaleEpub(PWSTR Path);
 	private:
 		void grayscaleImage(unsigned char* imageData, int width, int height);
+		void contrastImage(unsigned char* imageData, int width, int height, int contrast_value);
 };
 

Charcoal/x64/Debug/assets/books.html

@@ -127,6 +127,13 @@ <h3 id="result">BOOKS: </h3>
                     nameToGrayscale();
                 }
             </script>
+
+            <button class="button-28" onclick="contrastbutton()">Contrast</button>
+            <script>
+                function contrastbutton() {
+                    contrastValue();
+                }
+            </script>
 
             <div id="bs"></div>
             <button class="button-28" onclick="rmbooksbutton()">Remove Books</button>