Update readme

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README.md

@@ -182,7 +182,17 @@ Individual processors can be initialised and apply processing against images. Th
 new Brightness(50).Apply(sourceImage, targetImage, sourceImage.Bounds);
 ```
 
-For advanced usage the `Image<TColor, TPacked>` class is available allowing developers to implement their own color models in the same manner as Microsoft XNA Game Studio and MonoGame 
+Setting individual pixel values is perfomed as follows:
+
+```csharp
+Image image = new Image(400, 400);
+using (PixelAccessor<Color, uint> pixels = image.Lock())
+{
+    pixels[200, 200] = Color.White;
+}
+```
+
+For advanced usage the `Image<TColor, TPacked>` class is available allowing developers to implement their own color models in the same manner as Microsoft XNA Game Studio and MonoGame. 
 
 All in all this should allow image processing to be much more accessible to developers which has always been my goal from the start.