Merge pull request #22 from doryphores/large-image-threshold-option

Add largeImageThreshold option to control when to skip pixels

README.md

@@ -63,11 +63,16 @@ resemble.outputSettings({
     blue: 255
   },
   errorType: 'movement',
-  transparency: 0.3
+  transparency: 0.3,
+  largeImageThreshold: 1200
 });
 // resembleControl.repaint();
 ```
 
+By default, the comparison algorithm skips pixels when the image width or height is larger than 1200 pixels. This is there to mitigate performance issues.
+
+You can switch this modify this behaviour by setting the `largeImageThreshold` option to a different value. Set it to **0** to switch it off completely.
+
 --------------------------------------
 
 Created by [James Cryer](http://github.com/jamescryer) and the Huddle development team.

resemble.js

@@ -36,6 +36,8 @@ URL: https://github.com/Huddle/Resemble.js
 
 	var errorPixelTransformer = errorPixelTransform.flat;
 
+	var largeImageThreshold = 1200;
+
 	_this['resemble'] = function( fileData ){
 
 		var data = {};
@@ -347,7 +349,7 @@ URL: https://github.com/Huddle/Resemble.js
 
 			var skip;
 
-			if( (width > 1200 || height > 1200) && ignoreAntialiasing){
+			if(!!largeImageThreshold && ignoreAntialiasing && (width > largeImageThreshold || height > largeImageThreshold)){
 				skip = 6;
 			}
 
@@ -595,6 +597,8 @@ URL: https://github.com/Huddle/Resemble.js
 
 		pixelTransparency = options.transparency || pixelTransparency;
 
+		largeImageThreshold = options.largeImageThreshold || largeImageThreshold;
+
 		return this;
 	};