Need to keep assignment to image so subsequent chained methods can use updated image.

Author: BielinskiLukasz

src/main/java/com/assertthat/selenium_shutterbug/core/PageSnapshot.java

@@ -51,7 +51,7 @@ public PageSnapshot highlight(WebElement element) {
      */
     public PageSnapshot highlight(WebElement element, Color color, int lineWidth) {
         try {
-            ImageProcessor.highlight(image, new Coordinates(element, devicePixelRatio), color, lineWidth);
+            image = ImageProcessor.highlight(image, new Coordinates(element, devicePixelRatio), color, lineWidth);
         } catch (RasterFormatException rfe) {
             throw new ElementOutsideViewportException(ELEMENT_OUT_OF_VIEWPORT_EX_MESSAGE, rfe);
         }
@@ -93,7 +93,7 @@ public PageSnapshot highlightWithText(WebElement element, Color elementColor, in
        try {
            highlight(element, elementColor, 0);
            Coordinates coords = new Coordinates(element, devicePixelRatio);
-           ImageProcessor.addText(image, coords.getX(), coords.getY() - textFont.getSize() / 2, text, textColor, textFont);
+           image = ImageProcessor.addText(image, coords.getX(), coords.getY() - textFont.getSize() / 2, text, textColor, textFont);
        } catch (RasterFormatException rfe) {
            throw new ElementOutsideViewportException(ELEMENT_OUT_OF_VIEWPORT_EX_MESSAGE, rfe);
        }

src/main/java/com/assertthat/selenium_shutterbug/core/Snapshot.java

@@ -185,7 +185,7 @@ public T withThumbnail(double scale) {
      * @return instance of type Snapshot
      */
     public T monochrome() {
-        ImageProcessor.convertToGrayAndWhite(this.image);
+        this.image = ImageProcessor.convertToGrayAndWhite(this.image);
         return self();
     }