Find height and width of images?

[Anon]

I have a PHP/MySql site that uploads images to a file and puts the filepath in my database. When I reference the file everything works fine except for if I specify the dimensions of the image, it stretches, and if I don't specify them, then there is a high risk the image will stretch the tables it is in.

My idea for preventing this was to only specify dimensions once the image is over a certain width or height. Say I want images to be no larger than 400x300, then an image that is 450x250 I want it to show up as 400x250, etc, etc.

The problem is I don't know how to find out the size of the image. I can't ask the user for the dimensions since they will rarely know - what can I do to get the size and width of the image? Or is there another solution to this problem?

Thanks,
Ben

[Anon]

http://www.phpbuilder.com/manual/function.getimagesize.php

this might help, you could use it in your upload script.

[[deleted]]

One nifty solution is to just leave the dimentions out of the HTML, and let the browser fix it.

But you can always get the dimensions of stored files using the GD library: http://www.php.net/manual/en/function.imagesx.php

BTW: don't mess about with the ratios, don't change an image from 450x250 to 400x250, keep the aspect ratio and change it to 400x222 instead.

[Anon]

How would I keep an aspect ratio?

[cheald]

One of my personal functions that I wrote explicitly for this purpose. It takes an image path and a maximum dimension for a side, and returns an array like:

array (
"width" => $new_width,
"height" => $new_height
);

Just use those values in your image tag, and you're good to go. Doesn't even require the GD library.

function scale($picture, $max) {
$c = 0;
$picsize = $max;
if($size = GetImageSize($picture)) {
$width = $size[0];
$height = $size[1];
if($width >= $height && $width > $picsize) {
$height = floor(($picsize / $width) $height);
$width = $picsize;
}
elseif($width < $height && $height > $picsize) {
$width = floor(($picsize / $height) $width);
$height = $picsize;
}
}
return array($width, $height);
}

[[deleted]]

The aspect ratio is the ratio between width and height.

If you want to decrease the width, make sure you decrease the height by the same percentage.
old_width / new_width = old_height / new_height

[Anon]

Ben,

If files are being uploaded, then why not use an image manipulator as soon as the file gets uploaded. ImageMagick has a mogrify function, that can adjust image sizes, maintain aspect ratios and only adjust if images are larger than the required size

eg
mogrify -geometry 400x225> image.jpg

will reduce the image proportionally until one of the limits is reached (ie 400 high OR 225 wide) ONLY if the image is larger than 400x225.

Similarly, if you don't care about the final width but need to reduce to 400 heigh maintaining the same aspect ratio:
mogrify -geometry 400> image.jpg

or vice versa for width:
mogrify -geometry x225> image.jpg

hope it helps