Imagick::thresholdImage
Here is a function to calculate the new dimensions of a thumbnail, to fit within the given dimensions on both sides.
<?php
/**
* Calculate new image dimensions to new constraints
*
* @param Original X size in pixels
* @param Original Y size in pixels
* @return New X maximum size in pixels
* @return New Y maximum size in pixels
*/
function scaleImage($x,$y,$cx,$cy) {
//Set the default NEW values to be the old, in case it doesn't even need scaling
list($nx,$ny)=array($x,$y);
//If image is generally smaller, don't even bother
if ($x>=$cx || $y>=$cx) {
//Work out ratios
if ($x>0) $rx=$cx/$x;
if ($y>0) $ry=$cy/$y;
//Use the lowest ratio, to ensure we don't go over the wanted image size
if ($rx>$ry) {
$r=$ry;
} else {
$r=$rx;
}
//Calculate the new size based on the chosen ratio
$nx=intval($x*$r);
$ny=intval($y*$r);
}
//Return the results
return array($nx,$ny);
}
?>
Use it like this:
<?php
//Read original image and create Imagick object
$thumb=new Imagick($originalImageFilename);
//Work out new dimensions
list($newX,$newY)=scaleImage(
$thumb->getImageWidth(),
$thumb->getImageHeight(),
$newMaximumWidth,
$newMaximumHeight);
//Scale the image
$thumb->thumbnailImage($newX,$newY);
//Write the new image to a file
$thumb->writeImage($thumbnailFilename);
?>
Imagick::thumbnailImage
(PECL imagick 2.0.0)
Imagick::thumbnailImage — Changes the size of an image
Description
bool Imagick::thumbnailImage
( int $columns
, int $rows
[, bool $bestfit = false
] )
Warning
This function is currently not documented; only its argument list is available.
Changes the size of an image to the given dimensions and removes any associated profiles. The goal is to produce small low cost thumbnail images suited for display on the Web. If TRUE is given as a third parameter then columns and rows parameters are used as maximums for each side. Both sides will be scaled down until the match or are smaller than the parameter given for the side.
Note: The behavior of the parameter bestfit changed in Imagick 3.0.0. Before this version given dimensions 400x400 an image of dimensions 200x150 would be left untouched. In Imagick 3.0.0 and later the image would be scaled up to size 400x300 as this is the "best fit" for the given dimensions. If bestfit parameter is used both width and height must be given.
Parameters
- columns
-
Image width
- rows
-
Image height
- bestfit
-
Whether to force maximum values
Return Values
Returns TRUE on success.
Errors/Exceptions
Throws ImagickException on error.
add a note
User Contributed NotesImagick::thumbnailImage
Anonymous
02-Jul-2008 11:15
02-Jul-2008 11:15
n-sw-bit at ya dot ru
09-Jun-2008 04:48
09-Jun-2008 04:48
If you want to resize your picture to fit smallest parameter:
$fitbyWidth = (($maxWidth/$w)<($maxHeight/$h)) ?true:false;
if($fitbyWidth){
$im->thumbnailImage($maxWidth, 0, false);
}else{
$im->thumbnailImage(0, $maxHeight, false);
}
sgarner at expio dot co dot nz
17-Oct-2007 05:11
17-Oct-2007 05:11
With $fit == true, the image is resized proportionally so that its _smallest_ dimension matches the width or height specified, NOT both.
For example, if you say thumbnailImage(400, 400, true), on an image of 1600x800, it will be resized to 800x400, NOT 400x200 as you might expect.
The solution is to compare the original image's dimensions to the specified dimensions, and substitute zero for the smaller dimension, and set $fit = false.
i.e.: thumbnailImage(400, 0, false) would resize that 1600x800 image to 400x200.
raybdbomb . gmail
10-Sep-2007 11:18
10-Sep-2007 11:18
As noted here
http://php.net/manual/en/ref.imagick.php
With either of the params as 0, the aspect ratio is maintained.