PHP | imageinterlace() Function

The imageinterlace() function is an inbuilt function in PHP which is used to enable or disable interlace in an image. Interlacing (also known as interleaving) is a method of encoding a bitmap image such that a person who has partially received it sees a degraded copy of the entire image. One difference between interlaced and non-interlaced images on a website is that the former one is loaded in a low-quality version first and then it’s quality keeps improving as the website loads whereas a non-interlaced image is loaded in a fixed quality line by line from top to bottom when the website loads.

Syntax:

int imageinterlace( resource $image, int $interlace )

Parameters: This function accepts two parameters as mentioned above and described below:

• $image: It specifies the image to be interlaced.
• $interlace: It specifies whether to enable or disable interlacing.

Return Value: This function returns 1 if the interlace bit is set for the image, otherwise 0.

Below examples illustrate the imageinterlace() function in PHP:

Program 1: In this example we will enable interlacing.

<?php

// Create an image from URL
$im = imagecreatefrompng(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-13.png');

// Enable interlacing
imageinterlace($im, 1);

// View the output
header('Content-type: image/jpeg');
imagejpeg($im);
imagedestroy($im);
?>

Output:

Program 2: In this example we will disable interlacing.

<?php

// Create an image from URL
$im = imagecreatefrompng(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-13.png');

// Disable interlacing
imageinterlace($im, 0);

// View the output
header('Content-type: image/jpeg');
imagejpeg($im);
imagedestroy($im);
?>

Output:

Reference: https://www.php.net/manual/en/function.imageinterlace.php