jpeg - compress and resize any image uploaded???

rupertbj

This is not a post asking how to upload images - I can do that! - just dealing with the images once they are uploaded!

I am working on a couple of sites where it would be super-useful to be able to select a file (a jpeg image from a digital camera) to be uploded and have a php script save two sets of that image, one as a thumbnail of width 160 px and a larger image of width 640 px.

Also, can I use php to compress the jpeg images by say 40%?

I am doing all the work in photoshop at the moment, and it would save me a lot of time!

So, resize the image twice - thumbnail width 160 px and image width 640 px - and save both as compressed jpeg images at 40% compression.

Thanks for any help you can give!

acidbox

If you have ImageMagick installed, you can use it from within PHP to modify/resize your images no problem.

For instance

$img_size = getimagesize($uploaded_file);
if($img_size[0] > 640) {
		exec("/usr/local/bin/convert -resize 640x480 -quality 40 $uploaded_file $uploaded_file");
		exec("exit(0)");
	}

In this example, I use the getimagesize function to find the size of the uploaded file. Then, I say, if the width ($img_size[0]) of the file is > 640, resize the image to 640x480 with a quality of 40. Using $img_size[1] will return the height.

This is one of the many many tools that ImageMagick offers. I use it and love it 😉

If you prefer to use the GD library which comes bundled in php 4.3.0+ instead of ImageMagick, you might want to check out this thread: http://www.phpbuilder.com/board/showthread.php?s=&threadid=10222182

I still prefer ImageMagick though.

rupertbj

Thanks acid! I'll work on it!

In the meantime how do I tell if either GD or ImageMagick are installed (aside from waiting for a reply to my email to my hosting provider)

acidbox

Well, if PHP 4.3.0+ is installed, chances are, GD is installed. To check, make a php file that looks like this:

<?php
phpinfo();
?>

Run that file and look to see if GD Library is enabled.

To test for ImageMagick, just try to run the script I have above. If it cant find the program, then it's probably not installed. Although, it's really easy for your host to install.

You may need to ask them to allow you to have safe mode turned off as well because the exec() command executes a file right from linux or windows. Most times it is default to On.

rupertbj

Also, it just occurred to me that I only want to specify the width. The height should be relative to the width. How would I amend the ImageMagick script above to do that?

rupertbj

Well, if PHP 4.3.0+ is installed, chances are, GD is installed. To check, make a php file that looks like this:

acid

The version of PHP is: PHP Version 4.0.4pl1

And GD is not installed - I'll try out ImageMagick

acidbox

Originally posted by rupertbj
Also, it just occurred to me that I only want to specify the width. The height should be relative to the width. How would I amend the ImageMagick script above to do that?

If the dimensions are smaller than 480, it won't stretch it to reach 480, but rather leave it at its proportional dimensions. So, it already does what you want.

Additionally, I would really suggest that you upgrade your php to version 4.3.2 You have a hack waiting to happen with that ancient version.

rupertbj

acid,

I'll take it up with my hosting provider - unfortunately I have no control over it!