davidsonfellipe · davidsonfellipe · Jul 31, 2020 · Jul 30, 2020 · Jul 31, 2020
diff --git a/dist/bundle.js b/dist/bundle.js
@@ -1,6 +1,6 @@
 
 /*
- *  lena.js - 0.3.1
+ *  lena.js - 0.5.0
  *  Library for image processing <https://github.com/davidsonfellipe/lena-js/>
  *
  *  Made by Davidson Fellipe.
@@ -21,6 +21,49 @@ const invert = function (pixels) {
   return pixels
 };
 
+const contrast = function (pixels, amount) {
+  const level = Math.pow((amount + 100) / 100, 2);
+
+  let data = pixels.data;
+  let r;
+  let g;
+  let b;
+
+  for (let i = 0; i < data.length; i += 4) {
+    r = data[i];
+    g = data[i + 1];
+    b = data[i + 2];
+
+    r = r / 255;
+    r -= 0.5;
+    r *= level;
+    r += 0.5;
+    r *= 255;
+
+    g = g / 255;
+    g -= 0.5;
+    g *= level;
+    g += 0.5;
+    g *= 255;
+
+    b = b / 255;
+    b -= 0.5;
+    b *= level;
+    b += 0.5;
+    b *= 255;
+
+    r = r < 0 ? 0 : r > 255 ? 255 : r;
+    g = g < 0 ? 0 : g > 255 ? 255 : g;
+    b = b < 0 ? 0 : b > 255 ? 255 : b;
+
+    data[i] = r;
+    data[i + 1] = g;
+    data[i + 2] = b;
+  }
+
+  return pixels
+};
+
 const mirror = function (pixels) {
   let tmp = [];
   const width = pixels.width * 4;
@@ -111,7 +154,7 @@ const brightness = function (pixels, amount = 0) {
   return pixels
 };
 
-const sepia = function (pixels) {
+const sepia = function (pixels, amount = 100) {
   for (let i = 0; i < pixels.data.length; i += 4) {
     let r = pixels.data[i],
       g = pixels.data[i + 1],
@@ -151,16 +194,15 @@ const saturation = function (pixels) {
   return pixels
 };
 
-const thresholding = function (pixels, args) {
+const thresholding = function (pixels, amount = 128) {
   for (let i = 0; i < pixels.data.length; i += 4) {
     let r = pixels.data[i],
       g = pixels.data[i + 1],
       b = pixels.data[i + 2];
 
     let v = 0.2126 * r + 0.7152 * g + 0.0722 * b;
-    let thr = args || 128;
 
-    pixels.data[i] = pixels.data[i + 1] = pixels.data[i + 2] = v > thr ? 255 : 0;
+    pixels.data[i] = pixels.data[i + 1] = pixels.data[i + 2] = v > amount ? 255 : 0;
   }
 
   return pixels
@@ -494,6 +536,7 @@ exports.bigGaussian = bigGaussian;
 exports.blue = blue;
 exports.brightness = brightness;
 exports.canny = canny;
+exports.contrast = contrast;
 exports.filterImage = filterImage;
 exports.gaussian = gaussian;
 exports.getImage = getImage;

diff --git a/dist/bundle.min.js b/dist/bundle.min.js
diff --git a/docs/all-filters.html b/docs/all-filters.html
@@ -10,7 +10,7 @@
   <body>
     <div id="result" class="board">
       <div class="box">
-        <img id="image" src="assets/img/coffee.jpg" width="300" height="400" />
+        <img id="image" src="assets/img/sf.png" width="300" height="400" />
       </div>
     </div>
 
@@ -21,6 +21,12 @@
       var result = document.getElementById('result')
 
       var filters = [
+        { name: 'contrast', amount: 100 },
+        { name: 'contrast', amount: 50 },
+        { name: 'contrast', amount: 0 },
+        { name: 'contrast', amount: -50 },
+        { name: 'contrast', amount: -100 },
+        { name: 'grayscale', amount: 0 },
         { name: 'brightness', amount: -50 },
         { name: 'brightness', amount: 0 },
         { name: 'brightness', amount: 50 },
@@ -31,7 +37,6 @@
         { name: 'invert', amount: 0 },
         { name: 'mirror', amount: 0 },
         { name: 'thresholding', amount: 0 },
-        { name: 'grayscale', amount: 0 },
         { name: 'sepia', amount: 0 },
         { name: 'saturation', amount: 0 },
         { name: 'roberts', amount: 0 },

diff --git a/docs/assets/img/camera.png b/docs/assets/img/camera.png
diff --git a/docs/assets/img/sf.png b/docs/assets/img/sf.png
diff --git a/lib/filters/contrast.js b/lib/filters/contrast.js
@@ -0,0 +1,44 @@
+const contrast = function (pixels, amount) {
+  const level = Math.pow((amount + 100) / 100, 2)
+
+  let data = pixels.data
+  let r
+  let g
+  let b
+
+  for (let i = 0; i < data.length; i += 4) {
+    r = data[i]
+    g = data[i + 1]
+    b = data[i + 2]
+
+    r = r / 255
+    r -= 0.5
+    r *= level
+    r += 0.5
+    r *= 255
+
+    g = g / 255
+    g -= 0.5
+    g *= level
+    g += 0.5
+    g *= 255
+
+    b = b / 255
+    b -= 0.5
+    b *= level
+    b += 0.5
+    b *= 255
+
+    r = r < 0 ? 0 : r > 255 ? 255 : r
+    g = g < 0 ? 0 : g > 255 ? 255 : g
+    b = b < 0 ? 0 : b > 255 ? 255 : b
+
+    data[i] = r
+    data[i + 1] = g
+    data[i + 2] = b
+  }
+
+  return pixels
+}
+
+export default contrast
diff --git a/lib/index.js b/lib/index.js
@@ -1,4 +1,5 @@
 export { default as invert } from './filters/invert'
+export { default as contrast } from './filters/contrast'
 export { default as mirror } from './filters/mirror'
 
 // RGB filters

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lena.js",
-  "version": "0.4.2",
+  "version": "0.5.0",
   "description": "Library for image processing",
   "homepage": "https://github.com/davidsonfellipe/lena-js/",
   "author": {