add spelling normalise as an alias for normalize

README.md

@@ -482,7 +482,7 @@ This is a linear operation. If the input image is in a non-linear colour space s
 
 The output image will still be web-friendly sRGB and contain three (identical) channels.
 
-#### normalize()
+#### normalize() / normalise()
 
 Stretch histogram to cover full dynamic range before output to enhance contrast.
 

index.js

@@ -337,6 +337,7 @@ Sharp.prototype.normalize = function(normalize) {
   this.options.normalize = (typeof normalize === 'boolean') ? normalize : true;
   return this;
 };
+Sharp.prototype.normalise = Sharp.prototype.normalize;
 
 /*
   Convert to greyscale

test/unit/normalize.js

@@ -42,4 +42,8 @@ describe('Normalization', function () {
         return done();
       });
   });
+
+  it('uses the same prototype for both spellings', function () {
+    assert.strictEqual(sharp.prototype.normalize, sharp.prototype.normalise);
+  });
 });