How to Create Proportional Thumbnails in PHP for Large Images?

Creating Scaled Thumbnails in PHP

The provided code snippet successfully crops an image within a given dimension. However, for larger images, it may not produce the desired results. To address this issue, it is necessary to first resize the image, ensuring that the smaller dimension of the resized image matches the corresponding dimension of the thumbnail.

To create proportional thumbnails, follow these steps:

1. Determine the aspect ratios of the source image and the desired thumbnail.
2. Compare the aspect ratios. If the source image is wider, calculate the new height and width accordingly. Conversely, if the thumbnail is wider, calculate the new width and height.
3. Create a new image with the calculated dimensions.
4. Perform a resampling operation to resize the source image to fit the new dimensions while maintaining aspect ratio.
5. Crop the resized image to the specified thumbnail dimensions.
6. Save the cropped image as the thumbnail.

Here is an updated code example that implements these steps:

<code class="php">$image = imagecreatefromjpeg($_GET['src']);
$filename = 'images/cropped_whatever.jpg';

$thumb_width = 200;
$thumb_height = 150;

$width = imagesx($image);
$height = imagesy($image);

$original_aspect = $width / $height;
$thumb_aspect = $thumb_width / $thumb_height;

if ( $original_aspect >= $thumb_aspect )
{
   // If image is wider than thumbnail (in aspect ratio sense)
   $new_height = $thumb_height;
   $new_width = $width / ($height / $thumb_height);
}
else
{
   // If the thumbnail is wider than the image
   $new_width = $thumb_width;
   $new_height = $height / ($width / $thumb_width);
}

$thumb = imagecreatetruecolor( $thumb_width, $thumb_height );

// Resize and crop
imagecopyresampled($thumb,
                   $image,
                   0 - ($new_width - $thumb_width) / 2, // Center the image horizontally
                   0 - ($new_height - $thumb_height) / 2, // Center the image vertically
                   0, 0,
                   $new_width, $new_height,
                   $width, $height);
imagejpeg($thumb, $filename, 80);</code>

By incorporating image resizing into the thumbnail generation process, it is possible to create well-proportioned thumbnails that are independent of the original image size.

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