I cannot remove embedded barcode from the image. Due to saving compression.

Question

Hi guys,
I recreate a thread to prevent confusing on my previous one. Please only reply to this thread thanks.
Ok, for a start I will give some general description about the application I made.
I had some problem with the image being compressed while it is saved.
Because saving an image will cause it to compress and had its pixel valued changed, I could not successfully remove the bardcode that is embedded inside a image(although some of the pixel value will be returned to original normally). I had placed my code below and will accept any opinion that will help me solve the removal of barcode problem.
What my application does is actually very simple. It will take the pixel value of the area inside the image that will be embed with the barcode first, then it will take the pixel value of the barcode and use the formula (1-alpha * Image pixel value) + (alpha * barcode pixel value) = new pixel value which will contain the barcode that had been embedded inside. The formula works great but when I saved the image the pixel value will change due to compression. On the removal of barcode my application will read every pixel value from the image embedded with barcode (only the area with barcode embedded), then it will go on to read every pixel value of the barcode used for embedding and then use the formula (Embedded image pixel value - (alpha * Barcode pixel value) - (1 - alpha) = original pixel value. But due to the reason that compression will change some of the pixel inside the saved image to drop in its value, the result from the removal formula will be negative and hence caused my result image to become wierd as it will red colors instead of original color on some of its pixel. I tried saving under PNG format which people said to be lossless compression but the result is still the same.
So I need to ask you guys for opinion or help me find the part where I actually did wrongly and caused the image pixel value to change.
Thanks. Please proceed and read below for the codes that I used. It is messy and I will sort it out later.
When alpha is set as 1 the barcode will appear to be overwrite onto the image. But when alpha is set as 0.1 the barcode will appear to be transparent and almost seems to be not there on the image when embedded.
This is the code I used to retrieve image pixel when embedding:
public static int[] getImagePixelValue(BufferedImage image, int x, int y){
          //Create an array to store image RGB value
          int[] imageRGB = new int[3];
          //Get height and width from input image
          int imageWidth = image.getWidth();
          int imageHeight = image.getHeight();
          //Get raw RGB value from image
          int imageValue = image.getRGB(x, y);
          //Convert image raw RGB value
          int imageRed = ((image.getRGB(x, y) >> 16) & 0xff);
          int imageGreen = ((image.getRGB(x, y) >> 8) & 0xff);
          int imageBlue = image.getRGB(x, y) & 0xff;
          //Input the converted RGB value into the array
          imageRGB[0] = imageRed;
          imageRGB[1] = imageGreen;
          imageRGB[2] = imageBlue;
          /*//Print out the pixel value to check
          System.out.println("Image red pixel: "+imageRGB[0]);
          System.out.println("Image green pixel: "+imageRGB[1]);
          System.out.println("Image blue pixel: "+imageRGB[2]);*/
          //Return image RGB value
          return imageRGB;
}This is the code I used to retrieve barcode pixel for embedding:
public static int[] getWatermarkPixelValue(BufferedImage watermark, int x, int y){
          //Create an array to store watermark RGB value
          int[] watermarkRGB = new int[3];
          //Get height and width from input watermark
          int watermarkWidth = watermark.getWidth();
          int watermarkHeight = watermark.getHeight();
          int watermarkValue = watermark.getRGB(x, y);
          //Convert watermark raw RGB value
          int watermarkRed = ((watermark.getRGB(x, y) >> 16) & 0xff);
          int watermarkGreen = ((watermark.getRGB(x, y) >> 8) & 0xff);
          int watermarkBlue = watermark.getRGB(x, y) & 0xff;
          //Input the converted RGB value into the array
          watermarkRGB[0] = watermarkRed;
          watermarkRGB[1] = watermarkGreen;
          watermarkRGB[2] = watermarkBlue;
          /*//Print out the pixel value to check
          System.out.println("Watermark red pixel: "+watermarkRGB[0]);
          System.out.println("Watermark green pixel: "+watermarkRGB[1]);
          System.out.println("Watermark blue pixel: "+watermarkRGB[2]);*/
          //Return watermark RGB value
          return watermarkRGB;
     }This is the code I used for merging the image pixel and barcode pixel to get the embedded pixel value:
public static int[] getEmbeddedPixelValue(int[] imagePixelValue, int[] watermarkPixelValue, double alpha){
          //Create a object to hold embedded pixel value
          int[] embeddedRGBValue = new int[3];
          //Change image pixel value into double calculating equation
          double imgRedValue = (double) imagePixelValue[0];
          double imgGreenValue = (double) imagePixelValue[1];
          double imgBlueValue = (double) imagePixelValue[2];
          //Change watermark pixel value into double calculating equation
          double wmRedValue = (double) watermarkPixelValue[0];
          double wmGreenValue = (double) watermarkPixelValue[1];
          double wmBlueValue = (double) watermarkPixelValue[2];
          //Equation for embedding image and watermark together
          double embeddedRed = ((1.0 - alpha) * imgRedValue) + (alpha * wmRedValue);
          double embeddedGreen = ((1.0 - alpha) * imgGreenValue) + (alpha * wmGreenValue);
          double embeddedBlue = ((1.0 - alpha) * imgBlueValue) + (alpha * wmBlueValue);
          //Changing embedded value from double to int
          int embeddedRedValue = (int) embeddedRed;
          int embeddedGreenValue = (int) embeddedGreen;
          int embeddedBlueValue = (int) embeddedBlue;
          //input the embedded RGB value into the array
          embeddedRGBValue[0] = embeddedRedValue;
          embeddedRGBValue[1] = embeddedGreenValue;
          embeddedRGBValue[2] = embeddedBlueValue;
          //Return embedded pixel value
          return embeddedRGBValue;
     }This is the code where I used for the embedding process:
else if(target == embedButton){
               String xCoordinate = JOptionPane.showInputDialog(embedButton, "Enter coordinate X", "When you want to embed the watermark?", JOptionPane.QUESTION_MESSAGE);
               String yCoordinate = JOptionPane.showInputDialog(embedButton, "Enter coordinate Y", "When you want to embed the watermark?", JOptionPane.QUESTION_MESSAGE);
               int xValue = Integer.parseInt(xCoordinate);
               int yValue = Integer.parseInt(yCoordinate);
               int wCounter = 0;
               int hCounter = 0;
               //Create file object to be used in embedding and removing watermark
               File inputImage = new File(imagePath);
               File inputWatermark = new File(watermarkPath);
               //Convert string into double for calculation of embedded pixel value
               try {
                    alphaDouble = Double.valueOf(alphaValue).doubleValue();
               catch (NumberFormatException nfe) {
                    System.out.println("NumberFormatException: " + nfe.getMessage());
               try{
                    //Define selected image as testPic and make java read the file selected
                    BufferedImage image= ImageIO.read(inputImage);
                    BufferedImage watermark= ImageIO.read(inputWatermark);
                    BufferedImage testing;
                    //Get height and width value from the selected image
                    int imageWidth = image.getWidth();
                    int imageHeight = image.getHeight();
                    //Get height and width value from the selected barcode
                    int watermarkWidth = watermark.getWidth();
                    int watermarkHeight = watermark.getHeight();
                    int totalWidth = watermarkWidth + xValue;
                    int totalHeight = watermarkHeight + yValue;
                    //Use nested for loop to get RGB value from every pixel that the barcode will be embedded in the selected image
                    if(totalWidth <= imageWidth && totalHeight <= imageHeight){
                         for (int h = yValue ; h < totalHeight; h++){
                              for (int w = xValue; w < totalWidth; w++){
                                   int[] imagePixelValue = getImagePixelValue(image, w, h);
                                   int[] watermarkPixelValue = getWatermarkPixelValue(watermark, wCounter, hCounter);
                                   int[] embeddedPixelRGBValue = getEmbeddedPixelValue(imagePixelValue, watermarkPixelValue, alphaDouble);
                                   setRed(image, w, h, embeddedPixelRGBValue[0]);
                                   setGreen(image, w, h, embeddedPixelRGBValue[1]);
                                   setBlue(image, w, h, embeddedPixelRGBValue[2]);
                                   wCounter++;
                                   if(wCounter == watermarkWidth){
                                        wCounter = 0;
                                        hCounter++;
                    else{
                         JOptionPane.showMessageDialog(embedButton, "The watermark cannot be embedded at the coordinates.");
                    tempImage = image;
                    imageIcon = new ImageIcon(tempImage);
                    labelImage.setIcon(imageIcon);
                    imagePanel.add(labelImage);
                    container.add(imagePanel, BorderLayout.CENTER);
                    setVisible(true);
                    System.out.println("Embedding completed");
               catch(Exception errorEmbedding){
                    //If there is any error, the try and catch function will tell you the error
                    System.out.println("The following error occured: "+errorEmbedding);
          }This is the code I use to save the image that had been embedded with the barcode:
else if(target == saveAction){
               JFileChooser chooser = new JFileChooser();
               FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & GIF Images", "jpg", "gif");
               chooser.setFileFilter(filter);
               chooser.setCurrentDirectory(new File("."));
               int returnVal = chooser.showSaveDialog(getParent());
               if(returnVal == JFileChooser.APPROVE_OPTION) {
                    String name = chooser.getSelectedFile().getAbsolutePath();
                    //Create a string instant to hold outputImage path name
                    String saveFile = chooser.getSelectedFile().getName()+"."+fileType;
                    //Create file output to decide what name will be used to save the file
                    File outputImage = new File(saveFile);
                    try{
                         //Save the file with the name used
                         ImageIO.write((RenderedImage) tempImage,fileType,outputImage);
                    catch(Exception errorSaving){
                         //If there is any error, the try and catch function will tell you the error
                         System.out.println("The following error occured: "+errorSaving);
               else{
          }This is the code I used for removal process of barcode:
else if(target == removeButton){
               //Create file object to be used in embedding and removing watermark
               File inputImage = new File("removalTesting.jpg");
               //File inputWatermark = new File(watermarkPath);
               //Used a defined barcode for testing of removing barcode from embedded image
               File inputWatermark = new File("barcode.jpg");
               /*//Convert string into double for calculation of embedded pixel value
               try {
                    alphaDouble = Double.valueOf(alphaValue).doubleValue();
               catch (NumberFormatException nfe) {
                    System.out.println("NumberFormatException: " + nfe.getMessage());
               //Used a defined alpha value for testing of removing barcode from embedded image
               //alphaDouble = 0.5;
               //Create x and y value for the starting coordinates of barcode embedded in the embedded image
               int xValue = 0;
               int yValue = 0;
               int wCounter = 0;
               int hCounter = 0;
               try{
                    //Define selected image as testPic and make java read the file selected
                    BufferedImage image= ImageIO.read(inputImage);
                    BufferedImage watermark= ImageIO.read(inputWatermark);
                    //Get height and width value from the selected image
                    int imageWidth = image.getWidth();
                    int imageHeight = image.getHeight();
                    //Get height and width value from the selected barcode
                    int watermarkWidth = watermark.getWidth();
                    int watermarkHeight = watermark.getHeight();
                    int totalWidth = watermarkWidth + xValue;
                    int totalHeight = watermarkHeight + yValue;
                    //Use nested for loop to get RGB value from every pixel that the barcode had been embedded in the embedded image
                    if(totalWidth <= imageWidth && totalHeight <= imageHeight){
                         for (int h = yValue ; h < totalHeight; h++){
                              for (int w = xValue; w < totalWidth; w++){
                                   int[] imagePixelValue = getImagePixelValue(image, w, h);
                                   int[] watermarkPixelValue = getWatermarkPixelValue(watermark, wCounter, hCounter);
                                   int[] removedPixelRGBValue = getOriginalImagePixelValue(imagePixelValue, watermarkPixelValue, alphaDouble);
                                   setRed(image, w, h, removedPixelRGBValue[0]);
                                   setGreen(image, w, h, removedPixelRGBValue[1]);
                                   setBlue(image, w, h, removedPixelRGBValue[2]);
                                   wCounter++;
                                   if(wCounter == watermarkWidth){
                                        wCounter = 0;
                                        hCounter++;
                    tempImage = image;
                    imageIcon = new ImageIcon(tempImage);
                    labelImage.setIcon(imageIcon);
                    imagePanel.add(labelImage);
                    container.add(imagePanel, BorderLayout.CENTER);
                    setVisible(true);
                    System.out.println("Embedding completed");
               catch(Exception errorEmbedding){
                    //If there is any error, the try and catch function will tell you the error
                    System.out.println("The following error occured: "+errorEmbedding);
          }Sorry if the codes are in a mess, I did not had the time to sort it out yet but most likely do it when I got the removal of barcode done.
Follow this link to have a look of the result I see in my application when I got the barcode embedded into the image I selected:
[http://img356.imageshack.us/my.php?image=beforeremovalresultmg2.jpg]
Follow this link to have a look of the result I see in my application after I got the barcode removed:
[http://img523.imageshack.us/my.php?image=removalresultmx4.jpg]
As you can see from the link, after I remove the barcode from the image. Some of the pixel actually went back to normal in the barcode area when the the barcode is embedded into the image. But some pixel in the barcode area had its value changed due to compression when I save the image file I think.
Anyone can help me find out the problem?
Thanks.

Answer 1

KamenRider wrote:
I suspect the problem lies in the code when I save the image. Because people said that PNG was loseless compression but when I saved in PNG some of the pixel went back to normal while some did not. This is obviously the cause from changing of pixel value when I saved the image.You are almost certainly wrong. This is trivially easy to check. Print out the color of a certain pixel immediately before you save it. Open the saved PNG in your favorite image manipulation program and check the saved value of that same pixel. When you re-load the saved PNG, print out the color again. It should be unchanged.
Thanks you for trying to help me spot the problem but the formula is correct. The alpha value i used in my application is used to set the transparency of the barcode that will be embedded in the image. Hence, when alpha = 1 the new pixel value should be the barcode value. ^^The formula isn't wrong, it's just not doing what you think it's doing. Remember that you're working with ints here, not floating point numbers, so they have finite precision. When you case from double to int, fractions are dropped. As morgalr pointed out, your formula is:
(1-alpha * Image pixel value) + (alpha * barcode pixel value) = new pixel value You didn't show us the code for getOriginalImagePixelValue but I imagine it's:
original pixel value = (new pixel value - alpha * barcode pixel value) / (1 - alpha)On a piece of paper, take alpha = 0.9, image pixel = 17 and barcode pixel = 100. Calculate out what you should get for new pixel value and then calculate what you should get for original pixel value. You will find they don't match.