Added API doc

README.md

@@ -77,7 +77,7 @@ The class inherits from the `SegmentAnnotator` class.
     new PreSegmentAnnotator(imageURL, options)
 
 A class object to generate an annotation canvas from the given image URL. It
-internally calls `PreSegmentation` to retrieve a segmentation mask from a PNG 
+internally calls `PreSegmentation` to retrieve a segmentation mask from a PNG
 file.
 
  * `imageURL` - URL of an image to annotate. (Caution: do not use a large
@@ -255,10 +255,11 @@ based on the VLFeat implementation. The function takes the following options.
 
     PreSegmentation(imageURL, options)
 
-Javascript implementation of an image segmentation mask loader.
+Existing mask loader.
 
 The function takes the following options.
 
+ * `annotation` - Existing annotation URL (required).
  * `toDataURL` - Callback function to receive the result as a data URL.
  * `callback` - Function to be called on finish. The function takes a single
                 argument of result object that contains following fields.

pre-segmentation.js

@@ -1,12 +1,13 @@
 /**
- * Javascript import of a pre-segmentation algorithm from PNG annotated images.
+ * Pre-segmentation from PNG annotated images.
  *
  * API
  * ---
  *
- *    SLICSegmentation(imageURL, options)
+ *    PreSegmentation(imageURL, options)
  *
  * The function takes the following options.
+ * * `annotation` - URL of the annotation PNG data.
  * * `toDataURL` - Callback function to receive the result as a data URL.
  * * `callback` - Function to be called on finish. The function takes a single
  *                argument of result object that contains following fields.
@@ -22,23 +23,20 @@
  * Jonathan Passerat-Palmbach 2015.
  */
 (function() {
-
   // Compute Pre-Segmentation.
   function computePreSegmentation(imageData, options) {
-
     var d = imageData.data;
     var numPixels = imageData.width * imageData.height;
     var segmentation = new Int32Array(numPixels);
-
-    // can skip with a stride of 4 since labels' RGB components are all the same
+    // can skip with a stride of 4 since labels' RGB components are all the
+    // same.
     for (var i = 0; i < numPixels; i++) {
-      // TODO would be great to rewrite this ugly loop
+      // TODO would be great to rewrite this ugly loop.
       segmentation[i] = d[i*4];
     }
-
     return segmentation;
   }
-  
+
   // Remap label indices.
   function remapLabels(segmentation) {
     var map = {},
@@ -51,16 +49,14 @@
     }
     return index;
   }
-
-  // retrieve segmentation from label map
-  function retrieveSegmentation(annotationsImageData, imageData, options) {
 
+  // Retrieve segmentation from label map.
+  function retrieveSegmentation(annotationsImageData, imageData, options) {
     var segmentation = computePreSegmentation(annotationsImageData, options);
-
-    // numSegments is not necessarilly the biggest label as there might be a gap in labels presence in the image ex: [0, 1, 3, 4] 
-    // still fine as the export preserves the original labels \o/
+    // numSegments is not necessarilly the biggest label as there might be a
+    // gap in labels presence in the image ex: [0, 1, 3, 4] still fine as the
+    // export preserves the original labels \o/
     var numSegments = remapLabels(segmentation);
-
     if (options.callback) {
       var rgbData = new Uint8Array(imageData.data);
       options.callback({
@@ -71,10 +67,8 @@
         rgbData: rgbData
         });
       }
-
-    if (options.toDataURL) {
-      var dataurl = getDataURL(imageData.width, imageData.height, indexMap, options);
-    }
+    if (options.toDataURL)
+      getDataURL(imageData.width, imageData.height, indexMap, options);
   }
 
   // Convert to Data URL.
@@ -101,17 +95,16 @@
     canvas.width = image.width;
     canvas.height = image.height;
     var context = canvas.getContext('2d');
-
-    // draw actual image 
+    // draw actual image.
     context.drawImage(image, 0, 0);
     var imageData = context.getImageData(0, 0, image.width, image.height);
-
     var annotations = new Image();
     annotations.src = options.annotation;
     annotations.crossOrigin = null;
     annotations.onerror = function() { onErrorImageLoad(annotations); };
-    annotations.onload = function() { onSuccessAnnotationLoad(annotations, imageData, options); };
-
+    annotations.onload = function() {
+      onSuccessAnnotationLoad(annotations, imageData, options);
+    };
   }
 
   // When annotations are loaded.
@@ -120,15 +113,20 @@
     canvas.width = annotations.width;
     canvas.height = annotations.height;
     var context = canvas.getContext('2d');
-    
-    // draw actual image 
+
+    // Draw actual image.
     context.drawImage(annotations, 0, 0);
-    var annotationsImageData = context.getImageData(0, 0, annotations.width, annotations.height);
-
-    // fill in `segmentation` with retrieved annotations
-    segmentation = retrieveSegmentation(annotationsImageData, imageData, options);
+    var annotationsImageData = context.getImageData(0,
+                                                    0,
+                                                    annotations.width,
+                                                    annotations.height);
+
+    // Fill in `segmentation` with retrieved annotations.
+    segmentation = retrieveSegmentation(annotationsImageData,
+                                        imageData,
+                                        options);
   }
-  
+
   // When image is invalid.
   function onErrorImageLoad(image) {
     alert('Failed to load an image: ' + image.src);
@@ -137,12 +135,14 @@
   // Public API.
   window.PreSegmentation = function(imageURL, options) {
     if (typeof options === 'undefined') options = {};
-
+    if (options.annotation)
+      throw "Annotation URL missing";
+
     var image = new Image();
     image.src = imageURL;
     image.crossOrigin = null;
     image.onerror = function() { onErrorImageLoad(image); };
     image.onload = function() { onSuccessImageLoad(image, options); };
-    
+
   };
 }).call(this);