Image Processing

Grayscale

An implementation of digital image processing to convert RGB image or colormap to grayscale (rgb2gray).

Content

• Requirements
• Programming
• Running

Requirements

• PHP

Programming

• create file grayscale.php

<?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 + $g + $b) / 3);
  imageColorSet($img,$x,$avg,$avg,$avg);
}

$img_grayscale = 'lena_grayscale.png';
imagepng($img, $img_grayscale);
imagedestroy($img);

?>

Running

• Issue below command
  

  # php ./grayscale.php
  

Result

Original	Grayscale

Demo

• Demo Site

Reference

Note:

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