javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated error in Amazon AWS Java Code

To access Amazon Glacier, S3 etc if you're working on Java then you may get this exception:

javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated

I'm not an expert but only average IQ programmer.

What I understand is that the Amazon AWS client code is trying to authenticate with Amazon's remote server but since it does not have it's certificate it is giving this exception.

There are two solutions:

• Disable checking of certified certificate entirely

  You can you use some classes to skip using certificates ( link1, link2, link3,link4,link5) but below method is simplest in case of AWS. To do it just add this flag in the command line when running using java:

  -Dcom.amazonaws.sdk.disableCertChecking=true

  You can search this string "com.amazonaws.sdk.disableCertChecking" in the AWS api code and you will find it. Or just type this command in Unix/Linux "find . -name '*.java'| xargs egrep com.amazonaws.sdk.disableCertChecking " which will show you the file name.

  Remember using this method you're bypassing security while information transfer, do it only if it is safe to do so in Amazon Glacier, S3 etc.

• Import the certificate in the keystore. I've never done this but here are some links to get you started:
  1. Link1
  2. Link2

How to Linear Stretch any Image(Jpg/Png/Gif) Histogram in Java to improve it's contrast

So you want to stretch an image histogram linearly in Java to remove shadow and improve contrast?
Let us assume that a pixel contains 3 channels : RGB. That means each pixel of size 4 bytes has last 3 bytes as RGB while the first is 0.
Just like Photoshop->Image->Adjustments->Levels you can stretch each component(RGB) separately using a min and max value. If you've a dark image with low light then you can see the improvement.
The actual idea is plot the histogram of each channel and find the lowest and maximum pixel values and stretch them to 0 to 255. Then the image will become bright.
Here is the code that does that. Remember you can use any format jpg/png/gif etc input and output image.
What I'm doing is first getting each pixel(int of size 4 bytes in java) and then extracting 1 byte value each of RGB component, stretch it and put it back in a new file format. The RGB are stored in each byte numbering 2,3,4. The first byte is not important to us. Last three are. So that's why shifting(<<,>>) and masking 0xff are done in the code.
Here is the java resource for image format/bufferedimage conversion. Here is the linear stretching algorithm. Here the input file is IMG_3955.JPG and output is Newout.jpg but both could be any formats.
Just set the min and max variables to the window to stretch and change the input filename. This program also dumps the histogram of each channel(r/g/b) before histogram stretch - ie actual values and after r/g/b are stretched.
DOWNLOAD THE SOURCE CODE HERE.  Read the readme.txt file.

/**
  *
  * Read readme.txt
  */
  import java.awt.image.*;
  import java.io.*;
  import java.util.*;
  import java.awt.image.BufferedImage;
  import java.io.File;
  import javax.imageio.ImageIO;


class StretchHistogram {


public static void main(String args[]) {
  System.out.println("hello");


BufferedImage img = null;
  try {
  img = ImageIO.read(new File("IMG_3955.JPG"));
  writeColorImageValueToFile(img);
  } catch (Exception e) {
  }
  }


public static void writeColorImageValueToFile(BufferedImage in) {
  int width = in.getWidth();
  int height = in.getHeight();
  
  int min = 0;  //stretch min level
  int max = 31; //stretch max level



System.out.println("width=" + width + " height=" + height);
  try {



int[] r = new int[width * height];
  int[] g = new int[width * height];
  int[] b = new int[width * height];
  int[] e = new int[width * height];
  int[] data = new int[width * height];
  in.getRGB(0, 0, width, height, data, 0, width);



int[] hist_refore_r = new int[256];
  int[] hist_refore_g = new int[256];
  int[] hist_refore_b = new int[256];


int[] hist_after_r = new int[256];
  int[] hist_after_g = new int[256];
  int[] hist_after_b = new int[256];


for (int i = 0; i < (height * width); i++) {
  r[i] = (int) ((data[i] >> 16) & 0xff);
  g[i] = (int) ((data[i] >> 8) & 0xff);
  b[i] = (int) (data[i] & 0xff);


hist_refore_r[r[i]]++;
  hist_refore_g[g[i]]++;
  hist_refore_b[b[i]]++;
  
  //System.out.println(r[i]+" "+g[i]+" "+b[i]);


//stretch them to 0 to 255
  r[i] = (int) (1.0*( r[i] - min) / (max - min) * 255);
  g[i] = (int) (1.0*( g[i] - min) / (max - min) * 255);
  b[i] = (int) (1.0*( b[i] - min) / (max - min) * 255);
  
  if(r[i]> 255) r[i]=255;
  if(g[i]> 255) g[i]=255;
  if(b[i]> 255) b[i]=255;
  
  if(r[i]<0) r[i]=0;
  if(g[i]<0) g[i]=0;
  if(b[i]<0) b[i]=0;


//System.out.println(r[i]+" "+g[i]+" "+b[i]);
  
  hist_after_r[r[i]]++;
  hist_after_g[g[i]]++;
  hist_after_b[b[i]]++;


//convert it back
  e[i] = (r[i] << 16) | (g[i] << 8) | b[i];


}
  //convert e back to say jpg
  in.setRGB(0, 0, width, height, e, 0, width);
  ImageIO.write(in, "jpeg" /* "png" "jpeg" ... format desired */,
  new File("newout.jpg") /* target */);



printhistogram(hist_refore_r, "hist_before_r.txt"); //before stretchig ie original
  printhistogram(hist_refore_g, "hist_before_g.txt");
  printhistogram(hist_refore_b, "hist_before_b.txt");
  printhistogram(hist_after_r, "hist_after_r.txt");  //after stretching ie modified ones
  printhistogram(hist_after_g, "hist_after_g.txt");
  printhistogram(hist_after_b, "hist_after_b.txt");



} catch (Exception e) {
  System.err.println("Error: " + e);
  Thread.dumpStack();


}
  }


static void printhistogram(int[] hist, String file) {
  try {
  FileWriter op = new FileWriter("F:/tmp/JavaApplication1/"+file);


for (int i = 0; i < hist.length; ++i) {
  op.write("[" + i + "]=" + hist[i]+"\n");
  }
  op.close();
  } catch (Exception e) {
  System.err.println("Error2: " + e);
  Thread.dumpStack();
  }
  }
  }

How to extract binary RGB raw pixel data in image formats in Java(jpg/gif/tif/png etc)?

So you want to extract the binary RGB pixels values from jpeg image format?

Let us assume that a pixel is composed of RGB values and all images are rectangular. Pixels are arranged in rows and columns. For a color image each pixel will have 3 components(RGB). It is exactly like channels in Photoshop. Now using the code below you can extract a component (R/G or B) from a color pixel and write it in individual file. This file will be black & while since it contains single color and has the same dimensions to that of original input image.

You can use any image format, just replace the file name in ImageIO.read and also each color file will be output in current directory as 1.out,2.out and 3.out. In these each pixel will be composed of single by(8 bits). It is unformatted raw image data.

/*
  * To change this template, choose Tools | Templates
  * and open the template in the editor.
  */
/**
  *
  * @author D14
  */
  import java.awt.image.*;
  import java.io.*;
  import java.util.*;
  import java.awt.image. BufferedImage;
  import java.io.File;
  import javax.imageio.ImageIO;
  class NewClass {
  public static void main(String args[])
  {
  System.out.println("hello");
  
  BufferedImage img = null;
  try {
  img = ImageIO.read(new File("F:/tmp/IMG_3955.JPG"));
  writeColorImageValueToFile(img);
  } catch (Exception e) {
  }
  }
public static void writeColorImageValueToFile(BufferedImage in) 
  { 
  int width = in.getWidth(); 
  int height = in.getHeight(); 
 System.out.println("width="+width+" height="+height);
  try 
  { 
  FileOutputStream fstream1 = new FileOutputStream("1.out"); 
  FileOutputStream fstream2 = new FileOutputStream("2.out");
  FileOutputStream fstream3 = new FileOutputStream("3.out");
  
  byte [] b = new byte[width * height];
  byte [] c = new byte[width * height];
  byte [] d = new byte[width * height];
 int [] data = new int[width * height]; 
  in.getRGB(0, 0, width, height, data, 0, width); 
  
  int min=0;
  int max=30;
 for(int i = 0; i < (height * width); i++) 
  { 
  b[i]=(byte)((data[i] >> 16) & 0xff);
  c[i]=(byte)((data[i] >> 8) & 0xff);
  d[i]=(byte)(data[i]  & 0xff);
  
  
  } 
  fstream1.write(b);
  fstream2.write(c);
  fstream3.write(d);
 
  } catch (Exception e) 
  { 
  System.err.println("Error: " + e.getMessage()); 
  } 
  } 
  }

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