Handling picture size

[Anon]

I'm building a site that allows people to upload their pictures, i've limited the file size to less than 30K. The problem is, sometimes, pictures that are uploaded can be of different heights and widths. I put height and width attributes on the <IMG> tags but that can lead to a distorted picture (ie: if a picture is small, it can be stretched out and look really blurred).

I want to display all pictures in a 250 x 250 square. Is there a way for PHP to detect the height and width of a picture and then make adjusts if it's too big and leave it otherwise?. Similarly, if the picture is tall (ie: height > width), I want it to size it to a specific height, widht ratio.

I hope that makes sense.
Mike

[Anon]

Mike,

You can use the getimagesize() function to find out the height and width of your image. More info at http://www.php.net/manual/en/function.getimagesize.php

There are lots of image related functions that will help you. More info can be found at http://www.php.net/manual/en/ref.image.php

[terje-s]

Like Mark says, you can use the getimagesize() function to obtain data about the image dimensions.

However, forcing an image to a certain width-height without maintaining the original ratio usually causes some pretty weird looking images. The way I do this on my site, is to first of all determine wich would cause me most trouble, if the image is too high or too wide. I have thought about this a number of times, and the conclusion always lands on 'wide'. So, if I use 100px for image width, and an image is less than 100px, geez, let it be. I don't care if the image is smaller, as long as it isn't larger and mess up my design.

So, what I'm going to paste you a portion of one of my scripts for image size conversion. Just to give you a hint on how I do it 🙂

$imageData holds information gathered using getimagesize(). So, basically, what I do is find a number that I can multiply the image width with to get an image with ~= $SETUP[image_tnWidth] pixels. If I now multiply the height by the same factor, I will get the image with the same ratio between height/width, yet scaled to a smaller image. Of course, you can do the same thing if you want to blow up smaller images. (Obviously you'd have to increase the $factor instead of decreasing it)

$factor = $SETUP[image_tnConvFactor]; / 1 by default /
$newWidth = $imageData[image_width] $factor;
while ($newWidth > $SETUP[image_tnWidth]) {
$factor -= 0.01;
$newWidth = round($imageData[image_width] $factor);
}
$newHeight = round($imageData[image_height] * $factor);

And now you'd have to perform the image size conversion, or just use the numbers for height/width in the <img>-tag. your call, hope it helped 🙂