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Image Processing

Monochrome (B&W Black-and-White)

An implementation of digital image processing to change RGB image or colormap to monochrome (black-and-white) image.

Content

Requirements

  • PHP

Programming

<?php

$img = imagecreatefrompng("../../lena.png");
imageTrueColorToPalette($img,true,256);
$numColors = imageColorsTotal($img);
for ($x = 0; $x < $numColors; $x++)
{
  list($r,$g,$b) = array_values(imageColorsForIndex($img,$x));
  $avg = intval($r * 0.299 + $g * 0.587 + $b * 0.114);
  if($avg >= 127) { 
    $avg = 255; 
  } else {
    $avg = 0;
  }
  imageColorSet($img,$x,$avg,$avg,$avg);
 }

 $img_monochrome = 'lena_monochrome.png';
 imagepng($img, $img_monochrome);
 imagedestroy($img);

?>

Running

  • Issue below command 
    # php ./monochrome.php

Result

Original Monochrome
r r