php Image Resize Over-Compressing - php

Question

Using the following script I´m getting over-compressed images on the front end. They appear fine on the server, but the imagesize.php seems to be destroying the end result. Here is a visual of the issue (ignore the slight difference in size on this image, that's my bad alignment) http://puu.sh/38VaP.png. Any ideas? Here is the script...
<?php
// Get the File path for the image
$imagedir = '../../imgs';
$imagename = $_GET["file"];
$sImagePath = "$imagedir/$imagename";
// If you want exact dimensions, you
// will pass 'width' and 'height'
$iThumbnailWidth = (int)$_GET['width'];
$iThumbnailHeight = (int)$_GET['height'];
// If you want proportional thumbnails,
// you will pass 'maxw' and 'maxh'
$iMaxWidth = (int)$_GET["maxw"];
$iMaxHeight = (int)$_GET["maxh"];
// Based on the above we can tell which
// type of resizing our script must do
if ($iMaxWidth && $iMaxHeight) $sType = 'scale';
else if ($iThumbnailWidth && $iThumbnailHeight) $sType = 'exact';
// The 'scale' type will make the image
// smaller but keep the same dimensions
// The 'exact' type will make the thumbnail
// exactly the width and height you choose
// To start off, we will create a copy
// of our original image in $img
$img = NULL;
// At this point, we need to know the
// format of the image
// Based on that, we can create a new
// image using these functions:
// - imagecreatefromjpeg
// - imagecreatefrompng
// - imagecreatefromgif
//$sExtension = strtolower(end(explode('.', $sImagePath)));
$explodedImagePath = explode('.',$sImagePath);
$sExtension = strtolower(end($explodedImagePath));
if ($sExtension == 'jpg' || $sExtension == 'jpeg') {
$img = #imagecreatefromjpeg($sImagePath)
or die("Cannot create new JPEG image");
} else if ($sExtension == 'png') {
$img = #imagecreatefrompng($sImagePath)
or die("Cannot create new PNG image");
} else if ($sExtension == 'gif') {
$img = #imagecreatefromgif($sImagePath)
or die("Cannot create new GIF image");
}
// If the image has been created, we may proceed
// to the next step
if ($img) {
// We now need to decide how to resize the image
// If we chose to scale down the image, we will
// need to get the original image propertions
$iOrigWidth = imagesx($img);
$iOrigHeight = imagesy($img);
if ($sType == 'scale') {
// Get scale ratio
$fScale = min($iMaxWidth/$iOrigWidth,
$iMaxHeight/$iOrigHeight);
// To explain how this works, say the original
// dimensions were 200x100 and our max width
// and height for a thumbnail is 50 pixels.
// We would do $iMaxWidth/$iOrigWidth
// (50/200) = 0.25
// And $iMaxHeight/$iOrigHeight
// (50/100) = 0.5
// We then use the min() function
// to find the lowest value.
// In this case, 0.25 is the lowest so that
// is our scale. The thumbnail must be
// 1/4th (0.25) of the original image
if ($fScale < 1) {
// We must only run the code below
// if the scale is lower than 1
// If it isn't, this means that
// the thumbnail we want is actually
// bigger than the original image
// Calculate the new height and width
// based on the scale
$iNewWidth = floor($fScale*$iOrigWidth);
$iNewHeight = floor($fScale*$iOrigHeight);
// Create a new temporary image using the
// imagecreatetruecolor function
$tmpimg = imagecreatetruecolor($iNewWidth,
$iNewHeight);
// The function below copies the original
// image and re-samples it into the new one
// using the new width and height
imagecopyresampled($tmpimg, $img, 0, 0, 0, 0,
$iNewWidth, $iNewHeight, $iOrigWidth, $iOrigHeight);
// Finally, we simply destroy the $img file
// which contained our original image
// so we can replace with the new thumbnail
imagedestroy($img);
$img = $tmpimg;
}
} else if ($sType == "exact") {
// Get scale ratio
$fScale = max($iThumbnailWidth/$iOrigWidth,
$iThumbnailHeight/$iOrigHeight);
// This works similarly to other one but
// rather than the lowest value, we need
// the highest. For example, if the
// dimensions were 200x100 and our thumbnail
// had to be 50x50, we would calculate:
// $iThumbnailWidth/$iOrigWidth
// (50/200) = 0.25
// And $iThumbnailHeight/$iOrigHeight
// (50/100) = 0.5
// We then use the max() function
// to find the highest value.
// In this case, 0.5 is the highest so that
// is our scale. This is the first step of
// the image manipulation. Once we scale
// the image down to 0.5, it will have the
// dimensions of 100x50. At this point,
// we will need to crop the image, leaving
// the height identical but halving
// the width to 50
if ($fScale < 1) {
// Calculate the new height and width
// based on the scale
$iNewWidth = floor($fScale*$iOrigWidth);
$iNewHeight = floor($fScale*$iOrigHeight);
// Create a new temporary image using the
// imagecreatetruecolor function
$tmpimg = imagecreatetruecolor($iNewWidth,
$iNewHeight);
$tmp2img = imagecreatetruecolor($iThumbnailWidth,
$iThumbnailHeight);
// The function below copies the original
// image and re-samples it into the new one
// using the new width and height
imagecopyresampled($tmpimg, $img, 0, 0, 0, 0,
$iNewWidth, $iNewHeight, $iOrigWidth, $iOrigHeight);
// Our $tmpimg will now have the scaled down
// image. The next step is cropping the picture to
// make sure it's exactly the size of the thumbnail
// The following logic choose how the image
// will be cropped. Using the previous example, it
// needs to take a 50x50 block from the original
// image and copy it over to the new thumbnail
// Since we want to copy the exact center of the
// scaled down image, we need to find out the x
// axis and y axis. To do so, say the scaled down
// image now has a width of 100px but we want it
// to be only 50px
// Somehow, we need to select between the 25th and
// 75th pixel to copy the middle.
// To find this value we do:
// ($iNewWidth/2)-($iThumbnailWidth/2)
// ( 100px / 2 ) - (50px / 2)
// ( 50px ) - ( 25px )
// = 25px
if ($iNewWidth == $iThumbnailWidth) {
$yAxis = ($iNewHeight/2)-
($iThumbnailHeight/2);
$xAxis = 0;
} else if ($iNewHeight == $iThumbnailHeight) {
$yAxis = 0;
$xAxis = ($iNewWidth/2)-
($iThumbnailWidth/2);
}
// We now have to resample the new image using the
// new dimensions are axis values.
imagecopyresampled($tmp2img, $tmpimg, 0, 0,
$xAxis, $yAxis,
$iThumbnailWidth,
$iThumbnailHeight,
$iThumbnailWidth,
$iThumbnailHeight);
imagedestroy($img);
imagedestroy($tmpimg);
$img = $tmp2img;
}
}
// Display the image using the header function to specify
// the type of output our page is giving
header("Content-type: image/jpeg");
imagejpeg($img);
}
?>

Answer 1

You can adjust the compression level using the third parameter to imagejpeg. For top quality (but biggest file size) use:
imagejpeg($img, NULL, 100);
A quality value of 90 will probably give you a reasonable balance between quality and file size.
Then again, the kind of image you have in the example may be best saved as PNG, with imagepng. The JPEG format is best used for photographic images.

Answer 2

Looks like you're destroying the image yourself:
imagedestroy($tmpimg);
$img = $tmp2img;
... snip ...
imagejpeg($tmpimg);
You cannot imagedestroy() until AFTER you have completely finished using the GD image handle, which includes outputting it via imagejpeg. once it's destroyed, the image is GONE from memory and the handle variable becomes invalid.