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• The transparent pixels in my Bitmap shown as white

  7 mai 2016, par Hassan Ibrahem

  I’m using c code to get frame from a gif file and it’s working fine using ffmpeg library av_read_frame, then I convert the returned image from this format BGRA to ARGB format using this method libyuv::ABGRToARGB.

  In the java part I receive the bitmap and when I put it in the ImageView the transparent pixels drawn white.

   Bitmap bitmap= Bitmap.createBitmap(150, 150, Bitmap.Config.ARGB_8888);
  
   getGifFrame(gifFile,bitmap); //native method which get image frame from gif file.
  
   imageTest.setImageBitmap(backgroundBitmap);//this bitmap in debug mode I can see that it has transparent pixels, but in drawn it appears white!

  even when I loop on the returned bitmap pixels and check for each pixel I find them transparent !

            for (int x = 0; x < b.getWidth(); x++)
  
              {
  
                  for (int y = 0; y < b.getHeight(); y++)
  
                  {
  
                      int color = b.getPixel(x, y);
  
                      if (color == Color.WHITE)//This condition never occurred 
  
                      {
  
                          b.setPixel(x, y, Color.TRANSPARENT);
  
                      }
  
                  }
  
              }

  Nothing happened and it’s still white. Then I did convert all transparent pixels to TRANSPARENT !! and guess what, It’s working !

  else if (color == Color.TRANSPARENT)
  
  {
  
    b.setPixel(x, y, Color.TRANSPARENT);
  
  }

  I don’t understand why that happen. Any help would be appreciated.

  EDIT 1 :
  I get all pixels from the bitmap and set them again without doing anything and it worked also !?

    bitmap.getPixels(pixels, 0, width, 0, 0, width, height);
  
    bitmap.setPixels(pixels, 0, width, 0, 0, width,height);

• How to add a color gradient to black and white in ffmpeg

  4 mai 2016, par Axiverse

  I’m converting a sequences of image files to video using ffmpeg. They are black and white representing a range of data. I want to apply a color gradient to the videos, something like black->white becomes black->red->orange->white.

  How do I do this with ffmpeg ?

• FFMPEG - How to get a blur effect, without altering the color white ?

  17 août 2016, par Hugo

  I need a picture, with blur effect background. I found the code works, but, the white color of the photos is lost ( only happens with white color)...

  Step1 : ffmpeg -i eyes.jpg -s 640x360 -qscale 1 bg.jpg
  Step2 : ffmpeg -i bg.jpg -filter_complex "[0:v]crop=640:360:0:0,boxblur=20[fg] ;[0:v][fg]overlay=0:0[v]" -map "[v]" -qscale 1 bg.jpg -y
  Step3 : ffmpeg -i bg.jpg -i eyes.jpg -filter_complex "overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2" -qscale 1 result.jpg
  

  Original photo :
  see original photo

  Result (white color is lost)
  see result photo

  Please I need help (The white color should remain).

  Thank you very much,
  Greetings,
  Hugo