Add deviation logging

Author: glibas

README.md

@@ -100,7 +100,8 @@ Below are some basic examples of usage.
 
 ### Screenshots comparison
 
-- Compare screenshot taken with the expected one with specified deviation rate:
+- Compare screenshot taken with the expected one with specified deviation rate (for example 0.1 represents that if image differences are less than 10% the images will be considered to be equal and no resulting image with highlighted differences
+ will be produced):
 ```java
   Shutterbug.shootPage(driver).equals(otherImage,0.1);
 ```

pom.xml

@@ -4,7 +4,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.assertthat</groupId>
     <artifactId>selenium-shutterbug</artifactId>
-    <version>1.4-SNAPSHOT</version>
+    <version>1.4</version>
     <name>selenium-shutterbug</name>
     <description>Utility library to create customized screenshots using Selenium WebDriver and Java AWT</description>
     <url>http://www.assertthat.com</url>

src/main/java/com/assertthat/selenium_shutterbug/utils/image/model/ImageData.java

@@ -6,6 +6,7 @@
 import java.awt.*;
 import java.awt.image.BufferedImage;
 import java.io.File;
+import java.text.DecimalFormat;
 
 @Getter
 public class ImageData {
@@ -55,7 +56,6 @@ private void createDifferencesImage(BufferedImage image, String pathDifferenceIm
                     output.setRGB(x, y, rgb1);
             }
         }
-
         FileUtil.writeImage(output, "png", new File(pathDifferenceImageFileName + ".png"));
     }
 
@@ -65,8 +65,14 @@ public boolean equalsEachPixels(ImageData imageData, double deviation) {
 
     private boolean equalsEachPixels(BufferedImage image, double deviation) {
         double p = calculatePixelsDifference(image);
-
-        return p == 0 || p <= deviation;
+        boolean areEqual =  p == 0 || p <= deviation;
+        if(!areEqual){
+            DecimalFormat df = new DecimalFormat("#");
+            df.setMaximumFractionDigits(8);
+            System.out.println("[INFO] Allowed deviation: " + df.format(deviation));
+            System.out.println("[INFO] Actual deviation: " + df.format(p));
+        }
+        return areEqual;
     }
 
     private double calculatePixelsDifference(BufferedImage image) {