Pixelate Images With PHP

3rd June 2009 - 3 minutes read time

The other day I needed to hide an image but keep the original image intact so rather than do complicated things with light and dark filters I decided the best way would be to pixelate the image. All that is required to pixelate an image is to shrink it down and then blow it up to the original size, thus reducing the quality of the image.

The following code will do this process for a jpeg image. The pixelate amount variable is used to reduce the width and height of the first image using division and then multiply them back again to the original values for the output image. Remember to change the ImageCreateFromJPEG() to the format you want.

$imgfile = 'mushrooms.jpg';
 
$image = ImageCreateFromJPEG($imgfile);
 
$imagex = imagesx($image);
$imagey = imagesy($image);
 
// Amount to pixelate
$pixelate_amount = 10;
 
# Create version of the original image:
$tmpImage = ImageCreateTrueColor($imagex, $imagey);
imagecopyresized($tmpImage, $image, 0, 0, 0, 0, round($imagex / $pixelate_amount), round($imagey / $pixelate_amount), $imagex, $imagey);
 
# Create 100% version ... blow it back up to it's initial size:
$pixelated = ImageCreateTrueColor($imagex, $imagey);
imagecopyresized($pixelated, $tmpImage, 0, 0, 0, 0, $imagex, $imagey, round($imagex / $pixelate_amount), round($imagey / $pixelate_amount));
 
header("Content-Type: image/JPEG");
 
imageJPEG($pixelated, "", 75);

This will take the following image:

Image of mushrooms, non pixelated

And change it into this:

Image of mushrooms, pixelated

PHP

Add new comment

The content of this field is kept private and will not be shown publicly.
CAPTCHA
4 + 1 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Related Content

Recreating Spotify Wrapped In PHP

17th March 2024

I quite like the end of the year report from Spotify that they call "Wrapped". This is a little application in which they tell you what your favorite artist was and what sort of genres you listened to the most during the year.

Read more

Should A Constructor Throw An Exception?

18th February 2024

Let's say you had a class that you wanted to use, but there was some sort of error in creating the object. This might be that the wrong parameters were passed, or the third party service (eg. a database) wasn't available at the time of creation.

Read more

PHP Question: Variable Reference

10th December 2023

Question

What does the following code print out?

function arrayPrint($array)
{
   echo implode(' ', $array);
}

$arrayA = [1, 2, 3];
$arrayB = $arrayA;
$arrayB[1] = 0;
arrayPrint($arrayA);

Read more

Creating An Authentication System With PHP and MariaDB

15th October 2023

Using frameworks to handle the authentication of your PHP application is perfectly fine to do, and normally encouraged. They abstract away all of the complexity of managing users and sessions that need to work in order to allow your application to function.

Read more

Creating Sparklines In PHP

17th September 2023

A sparkline is a very small line graph that is intended to convey some simple information, usually in terms of a numeric value over time. They tend to lack axes or other labels and are added to information readouts in order to expand on numbers in order to give them more context.

Read more