Merge pull request #25 from studio-YOLO/19-test-demo-change-exposure

update: added exposure tests and demo

demo/index.html

@@ -28,6 +28,7 @@
     <script type="module" src="scripts/change_opacity_demo.js"></script>
     <script type="module" src="scripts/change_shadow_demo.js"></script>-->
     <script type="module" src="scripts/change_tint_demo.js"></script>
+
 </body>
 
 </html>

demo/scripts/change_exposure_demo.js

@@ -0,0 +1,19 @@
+import EditPix from "../../src/editpix.js";
+
+const editpix = new EditPix();
+
+const url = "images/img7.jpeg";
+
+var image = new Image();
+image.src = url;
+
+//waiting image load
+image.onload = () => {
+
+    editpix.changeExposure(image, -30)
+        .then(resultImage => {
+            document.body.appendChild(image);
+            document.body.appendChild(resultImage);
+        })
+        .catch(error => { console.log(error) })
+}

src/core/change_exposure.js

@@ -21,3 +21,5 @@ function changeExposure(pixelArray, factor) {
     }
     return pixelArray;
 }
+
+export default changeExposure;

src/editpix.js

@@ -12,6 +12,8 @@ import changeSaturation from "./core/change_saturation.js";
 import changeBrightness from "./core/change_brightness.js";
 import toSepia from "./core/sepia.js";
 import changeOpacity from "./core/change_opacity.js";
+import changeShadows from "./core/change_shadows.js";
+import changeExposure from "./core/change_exposure.js";
 import changeTint from "./core/change_tint.js"
 
 var EditPix = function () { };
@@ -170,4 +172,11 @@ EditPix.prototype.changeShadows = (image, factor) => {
     return imageManager.convertToImage(changeShadows(pixelArray, factor), image.naturalWidth, image.naturalHeight);
 }
 
+EditPix.prototype.changeExposure = (image, factor) => {
+    if (factor < -100 || factor > 100)
+        throw new Error("Invalid exposure factor: must be a value between -100 and 100");
+    const pixelArray = imageManager.getPixelArray(image);
+    return imageManager.convertToImage(changeExposure(pixelArray, factor), image.naturalWidth, image.naturalHeight);
+}
+
 export default EditPix;

test/core.test.js

@@ -6,7 +6,8 @@ import changeTemperature from "../src/core/change_temperature.js";
 import changeOpacity from "../src/core/change_opacity.js";
 import changeShadows from "../src/core/change_shadows.js"
 import higherColorContrast from "../src/core/higher_contrast.js";
-import changeTint from "../src/core/change_tint.js"
+import changeExposure from "../src/core/change_exposure.js";
+import changeTint from "../src/core/change_tint.js";
 import changeSaturation from "../src/core/change_saturation.js"
 import changeBrightness from "../src/core/change_brightness.js";
 import utils from "../src/utils.js";
@@ -202,6 +203,30 @@ describe('higherColorContrast', () => {
     });
 });
 
+describe('changeExposure', () => {
+    test('should return an unchanged array if the factor is 0', () => {
+        const color = [67, 141, 23];
+        changeContrast(color, 0);
+        expect(color).toEqual([67, 141, 23]);
+    });
+    test('should return a brighter array for positive factors', () => {
+        const luma = (value) =>  (value[0] + value[1] + value[2])/3
+        const color = [67, 141, 23];
+        const luma1 = luma(color);
+        changeExposure(color, 20);
+        const luma2 = luma(color);
+        expect(luma1).toBeLessThan(luma2);
+    });
+    test('should return a darker array for positive factors', () => {
+        const luma = (value) =>  (value[0] + value[1] + value[2])/3
+        const color = [67, 141, 23];
+        const luma1 = luma(color);
+        changeExposure(color, -20);
+        const luma2 = luma(color);
+        expect(luma1).toBeGreaterThan(luma2);
+    });
+});
+
 describe('changeSaturation', () => {
     test('should not change anything if factor is 0', () => {
         const testColor1 = [173, 114, 255];

test/editpix.test.js

@@ -80,6 +80,25 @@ describe('EditPix changeShadows method', () => {
     });
 });
 
+describe('EditPix changeExposure method', () => {
+    test('should reject lower out-of-range factors', () => {
+        try {
+            const editPix = new EditPix();
+            editPix.changeExposure([0, 234, 87], 150);
+        } catch (e) {
+            expect(e).toEqual(new Error("Invalid exposure factor: must be a value between -100 and 100"));
+        }
+    });
+    test('should reject upper out-of-range factors', () => {
+        try {
+            const editPix = new EditPix(); 
+            editPix.changeExposure([0, 234, 87], -123);
+        } catch (e) {
+            expect(e).toEqual(new Error("Invalid exposure factor: must be a value between -100 and 100"));
+        }
+    });
+});
+
 describe('EditPix changeContrast method', () => {
     test('should reject lower out-of-range factors', () => {
         try {