Question: Write a method `changeBlue(weight)`. Do not change any color of the pixels in the first half of the picture. For the second half, change blue value of each pixel by `new blue=original blue * weight`. 

> 
> For example, if a pixel has values (200,100,100) and weight is 0.5,
>  then the new values will be (200,100,50). If the weight is 1.5, then
>  the new values will be (200,100,150). 
> 
> 
> 

You can use any image to test this method.

Here's what I have. I think I'm pretty close, but I'm getting some errors. Any advice is appreciated.

```
public void changeBlue(int weight)
{
    Pixel[] pixelArray = this.getPixels();
    Pixel pixelObj = null;
    int value = 0;
    int index = 0;

    while (index >= pixelArray.length/2)
    {

        pixelObj = pixelArray[index];

        value = pixelObj.getBlue();

        value = (value * weight);

        pixelObj.setBlue(value);

        index++;
    }
}

```

Answer: 
Why do you JSON.stringify your 'body'? You don't have to do that, it should work without JSON.stringify()

--

And by that I mean that you should either just send 'patient' or do a "body = patient;" and then send body.
```
addBookWithObservable(book:Book): Observable<Book> {
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });
return this.http.post(this.url, book, options)
           .map(this.extractData)
           .catch(this.handleErrorObservable);

```

<https://www.concretepage.com/angular-2/angular-2-http-post-example>