Both xyking and quickshiftin include errors in their comments. xyking's error is in looping through negative numbers. quickshifting is incorrect in stating that 0 *increases* contrast (it does not - it decreases it).
Here is a (tested, working) method to increment or decrement contrast:
<?php
class Images {
public function contrastImage($contrast, $imagePath){
$this->image = new Imagick();
$this->image->readImage($imagePath);
if ($contrast > 0){
for ($i = 1; $i < $contrast; $i++){
$this->image->contrastImage(1);
}
}else if ($contrast <= 0) {
for ($i = 0; $i > $contrast; $i--) {
$this->image->contrastImage(0);
}
}
}
}
?>
Imagick::contrastImage
(PECL imagick 2, PECL imagick 3)
Imagick::contrastImage — Change the contrast of the image
Beschreibung
Enhances the intensity differences between the lighter and darker elements of the image. Set sharpen to a value other than 0 to increase the image contrast otherwise the contrast is reduced.
Parameter-Liste
-
sharpen -
The sharpen value
Rückgabewerte
Liefert true bei Erfolg.
Fehler/Exceptions
Wirft ImagickException bei Fehlern.
Beispiele
Beispiel #1 Imagick::contrastImage()
<?php
function contrastImage($imagePath, $contrastType) {
$imagick = new \Imagick(realpath($imagePath));
if ($contrastType != 2) {
$imagick->contrastImage($contrastType);
}
header("Content-Type: image/jpg");
echo $imagick->getImageBlob();
}
?>
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User Contributed Notes 3 notes
removespam dot roland at tannerritchie dot com ¶
9 years ago
xyking ¶
14 years ago
Tip:
<?php
$image->contrastImage(1); //Increase contrast once
$image->contrastImage(1); //Increase contrast more
$image->contrastImage(1); //Increase contrast even more
$image->contrastImage(0); //Decrease contrast once
$image->contrastImage(0); //Decrease contrast more
$image->contrastImage(0); //Decrease contrast even more
//This could be made into a function like this:
public function contrast($level) {
$level = (int)$level;
if ($level < -10) {
$level = -10;
} else if ($level > 10) {
$level = 10;
}
if ($level > 0) {
for ($i = 0; $i < $level; $i++) {
$this->image->contrastImage(1);
}
} else if ($level < 0) {
for ($i = $level; $i > 0; $i--) {
$this->image->contrastImage(0);
}
}
}
?>
quickshiftin at gmail dot com ¶
10 years ago
xyking's comment is wrong so be careful if you read it. You pass a value of 0 to *increase* the contrast.
