Solved

Creating Image Thumbnails Using PHP

Posted on 2016-11-23
3
35 Views
Last Modified: 2016-11-24
Do you have a good example of how to Create Image Thumbnails Using PHP?
thank you
0
Comment
Question by:Braveheartli
3 Comments
 
LVL 54

Expert Comment

by:Julian Hansen
ID: 41900207
From this article https://davidwalsh.name/create-image-thumbnail-php
function make_thumb($src, $dest, $desired_width) {

	/* read the source image */
	$source_image = imagecreatefromjpeg($src);
	$width = imagesx($source_image);
	$height = imagesy($source_image);
	
	/* find the "desired height" of this thumbnail, relative to the desired width  */
	$desired_height = floor($height * ($desired_width / $width));
	
	/* create a new, "virtual" image */
	$virtual_image = imagecreatetruecolor($desired_width, $desired_height);
	
	/* copy source image at a resized size */
	imagecopyresampled($virtual_image, $source_image, 0, 0, 0, 0, $desired_width, $desired_height, $width, $height);
	
	/* create the physical thumbnail image to its destination */
	imagejpeg($virtual_image, $dest);
}

Open in new window

0
 
LVL 109

Accepted Solution

by:
Ray Paseur earned 500 total points
ID: 41900438
Here is my teaching example...
<?php // demo/image_thumbnail.php
/**
 * RESIZE AN IMAGE TO FIT INSIDE A DEFINED TRANSPARENT SPACE
 * USE CASE: <img src="image_thumbnail.php?i=your.jpg&w=150&h=100" />
 */
error_reporting(E_ALL);


// ACQUIRE THE ARGUMENTS - MAY WANT SOME SANITY TESTS HERE?
$thumb_w   = !empty($_GET["w"]) ? $_GET['w'] : 600;
$thumb_h   = !empty($_GET["h"]) ? $_GET['h'] : 400;
$image_url = !empty($_GET["i"]) ? $_GET['i'] : trigger_error("Missing GET argument 'i' for Image URL", E_USER_ERROR);;

// CREATE THE THUMBNAIL IMAGE RESOURCE AND FILL IN TRANSPARENT
$thumb = imagecreatetruecolor($thumb_w, $thumb_h);
imagesavealpha($thumb, TRUE);
$empty = imagecolorallocatealpha($thumb,0x00,0x00,0x00,127);
imagefill($thumb, 0, 0, $empty);

// GET ORIGINAL IMAGE DIMENSIONS
$array = getimagesize($image_url);
if ($array)
{
    list($image_w, $image_h) = $array;
}
else
{
    trigger_error("NO IMAGE $image_url", E_USER_ERROR);
}

// ACQUIRE THE ORIGINAL IMAGE
$image_ext = explode('.', $image_url);
$image_ext = end($image_ext);
$image_ext = trim(strtoupper($image_ext));
switch($image_ext)
{
    case 'JPG' :
    case 'JPEG' :
        $image = @imagecreatefromjpeg($image_url);
        if ($image) break;

    case 'PNG' :
        $image = @imagecreatefrompng($image_url);
        if ($image) break;

    default : trigger_error("UNKNOWN IMAGE TYPE: $image_url", E_USER_ERROR);
}

// GET THE LESSER OF THE RATIO OF THUMBNAIL H OR W DIMENSIONS
$ratio_w = ($thumb_w / $image_w);
$ratio_h = ($thumb_h / $image_h);
$ratio   = ($ratio_w < $ratio_h) ? $ratio_w : $ratio_h;

// COMPUTE THUMBNAIL IMAGE DIMENSIONS
$thumb_w_resize = $image_w * $ratio;
$thumb_h_resize = $image_h * $ratio;

// COMPUTE THUMBNAIL IMAGE CENTERING OFFSETS
$thumb_w_offset = ($thumb_w - $thumb_w_resize) / 2.0;
$thumb_h_offset = ($thumb_h - $thumb_h_resize) / 2.0;

// COPY THE IMAGE TO THE CENTER OF THE THUMBNAIL
imagecopyresampled
( $thumb
, $image
, $thumb_w_offset
, $thumb_h_offset
, 0
, 0
, $thumb_w_resize
, $thumb_h_resize
, $image_w
, $image_h
)
;

// SHOW THE NEW THUMB IMAGE
header('Content-type: image/png');
imagepng($thumb);

// RELEASE THE MEMORY USED BY THE RESOURCES
imagedestroy($thumb);
imagedestroy($image);

Open in new window

Here is a similar teaching example, showing how to resize and crop an image.  You can see it in  action on my server, here:
https://iconoun.com/demo/image_resize_and_crop.php
<?php // demo/image_resize_and_crop.php
/**
 * Resize an image proportionally
 * Crop to specified size
 *
 * https://www.experts-exchange.com/questions/28982826/resizeing-PHP-image.html
 */
error_reporting(E_ALL);

function resize_and_crop($original_image_url, $thumb_image_url, $thumb_w, $thumb_h, $quality=75)
{
    // ACQUIRE THE ORIGINAL IMAGE: http://php.net/manual/en/function.imagecreatefromjpeg.php
    $original = imagecreatefromjpeg($original_image_url);
    if (!$original) return FALSE;

    // GET ORIGINAL IMAGE DIMENSIONS
    list($original_w, $original_h) = getimagesize($original_image_url);

    // RESIZE IMAGE AND PRESERVE PROPORTIONS
    $thumb_w_resize = $thumb_w;
    $thumb_h_resize = $thumb_h;
    if ($original_w > $original_h)
    {
        $thumb_h_ratio  = $thumb_h / $original_h;
        $thumb_w_resize = (int)round($original_w * $thumb_h_ratio);
    }
    else
    {
        $thumb_w_ratio  = $thumb_w / $original_w;
        $thumb_h_resize = (int)round($original_h * $thumb_w_ratio);
    }
    if ($thumb_w_resize < $thumb_w)
    {
        $thumb_h_ratio  = $thumb_w / $thumb_w_resize;
        $thumb_h_resize = (int)round($thumb_h * $thumb_h_ratio);
        $thumb_w_resize = $thumb_w;
    }

    // CREATE THE PROPORTIONAL IMAGE RESOURCE
    $thumb = imagecreatetruecolor($thumb_w_resize, $thumb_h_resize);
    if (!imagecopyresampled($thumb, $original, 0,0,0,0, $thumb_w_resize, $thumb_h_resize, $original_w, $original_h)) return FALSE;

    // ACTIVATE THIS TO STORE THE INTERMEDIATE IMAGE
    // imagejpeg($thumb, 'thumbs/temp_' . $thumb_w_resize . 'x' . $thumb_h_resize . '.jpg', 100);

    // CREATE THE CENTERED CROPPED IMAGE TO THE SPECIFIED DIMENSIONS
    $final = imagecreatetruecolor($thumb_w, $thumb_h);

    $thumb_w_offset = 0;
    $thumb_h_offset = 0;
    if ($thumb_w < $thumb_w_resize)
    {
        $thumb_w_offset = (int)round(($thumb_w_resize - $thumb_w) / 2);
    }
    else
    {
        $thumb_h_offset = (int)round(($thumb_h_resize - $thumb_h) / 2);
    }

    if (!imagecopy($final, $thumb, 0,0, $thumb_w_offset, $thumb_h_offset, $thumb_w_resize, $thumb_h_resize)) return FALSE;

    // STORE THE FINAL IMAGE - WILL OVERWRITE $thumb_image_url
    if (!imagejpeg($final, $thumb_image_url, $quality)) return FALSE;
    return TRUE;
}


// USE CASE
echo '<a target="_blank" href="images/image_600x374.jpg">Original 600x374</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_100x100.jpg', 100, 100);
echo '<a target="_blank" href="thumbs/temp_100x100.jpg">100x100</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x100.jpg', 200, 100);
echo '<a target="_blank" href="thumbs/temp_200x100.jpg">200x100</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x300.jpg', 200, 300);
echo '<a target="_blank" href="thumbs/temp_200x300.jpg">200x300</a><br/>';

Open in new window

1
 
LVL 1

Author Closing Comment

by:Braveheartli
ID: 41900465
Thank you so much Ray Paseur.

You are the really great. Thank you so much.
0

Featured Post

Gigs: Get Your Project Delivered by an Expert

Select from freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely and get projects done right.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
UPDATE query not working in mysqli php 8 49
Can't find PHP files on account that has WordPress 3 25
ebay devID, appID, certID, userToken 2 25
PHP AJAX JSON 2 57
Introduction HTML checkboxes provide the perfect way for a web developer to receive client input when the client's options might be none, one or many.  But the PHP code for processing the checkboxes can be confusing at first.  What if a checkbox is…
3 proven steps to speed up Magento powered sites. The article focus is on optimizing time to first byte (TTFB), full page caching and configuring server for optimal performance.
The viewer will learn how to dynamically set the form action using jQuery.
The viewer will learn how to create and use a small PHP class to apply a watermark to an image. This video shows the viewer the setup for the PHP watermark as well as important coding language. Continue to Part 2 to learn the core code used in creat…

785 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question