title: How to programmatically change contrast of a bitmap in android?
body: <p>I want to programmatically change the contrast of bitmap. Till now I have tried this.</p>
  
  <pre><code>private Bitmap adjustedContrast(Bitmap src, double value)
      {
          // image size
          int width = src.getWidth();
          int height = src.getHeight();
          // create output bitmap
          Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
          // color information
          int A, R, G, B;
          int pixel;
          // get contrast value
          double contrast = Math.pow((100 + value) / 100, 2);
  
          // scan through all pixels
          for(int x = 0; x &lt; width; ++x) {
              for(int y = 0; y &lt; height; ++y) {
                  // get pixel color
                  pixel = src.getPixel(x, y);
                  A = Color.alpha(pixel);
                  // apply filter contrast for every channel R, G, B
                  R = Color.red(pixel);
                  R = (int)(((((R / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
                  if(R &lt; 0) { R = 0; }
                  else if(R &gt; 255) { R = 255; }
  
                  G = Color.green(pixel);
                  G = (int)(((((G / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
                  if(G &lt; 0) { G = 0; }
                  else if(G &gt; 255) { G = 255; }
  
                  B = Color.blue(pixel);
                  B = (int)(((((B / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
                  if(B &lt; 0) { B = 0; }
                  else if(B &gt; 255) { B = 255; }
  
                  // set new pixel color to output bitmap
                  bmOut.setPixel(x, y, Color.argb(A, R, G, B));
              }
          }
          return bmOut;
      }
  </code></pre>
  
  <p>But this does not work as expected. Please help me in this or provide any other solution to achieve this. Thanks in advance.</p>