Image resizing error

[teebo]

Hi everyone,

I have a simple script that resizes a JPG image and it seems that when the resolution (not the weight!) of the image is greater than 2000 x 1500, I get an annoying server error 500. At first I thought it could be a memory allocation error, but I tested an image at 3MB with a resolution of 300 x 300 and it works. Whereas the SAME image at 2200 x 1700 at 600KB fails.

How can this be? Is there a way to resize an image without using imagecreatefromjpeg?

Here is my script:

$g_srcfile = 'Test.jpg';

// Get new sizes
list($width, $height) = getimagesize($g_srcfile);

// Load
$thumb = imagecreatetruecolor(300, 300);
$source = imagecreatefromjpeg($g_srcfile);

// Resize
imagecopyresampled($thumb, $source, 0, 0, 0, 0, 300, 300, $width, $height);

// Output
// Content type
header('Content-type: image/jpeg');
imagejpeg($source);
die();

[bpat1434]

well, you could use the age-old CSS and HTML trick and just tell it to be X size 😉 But if you're creating thumbnails, then no. You have to use imagecreatefromjpeg().

What you might think about doing is utilizing some scaling techniques. here's a quick overview:

Set width of your thumbnail in pixels: 300 (from your above code)
Calculate proprotionate dimension: Original Height / 300 * Original Width (remember math order of operations, left to right)

If the image is tall (portrait):
The set width (300) becomes the height, and the calculated proportion becomes the width.

So all in all, a very short script to calculate dimensions would be:

$o_dims = getimagesize('original_image.jpg');
$is_tall = $o_dims[1] >= $o_dims[0];

$t_width = 300;
$t_height = ceil($o_dims[1] / $t_width * $o_dims[0]); // We'll round up ;)

if($is_tall)
{
  $t = $t_width;
  $t_width = $t_height;
  $t_height = $t;
}

That's very crude, but it works for creating a proportionate image. It won't, however, create an image that is limited in dimensions both width and height. But I'm sure you can figure that out 😉