Imagick jpg background isn't transparent on rotate - php

Question

I'm currently using imagemagick version ImageMagick 6.8.4-6 2013-04-04 Q16
with Imagick extension version 1620
I am trying to rotate a jpg image and merge this into another jpg image however when i merge the image i get a black box arround the image.
Please see the code i am using below:
public function image($images,$x,$y,$angle){
if($images != "" && $images != NULL){
$base = $this->instance;
$layer = new Imagick($images);
//resize image
if($this->id == 45){
$layer->scaleImage(329,0);
}
if($this->id == 44){
$layer->scaleImage(280,0);
}
if($this->id == 42){
$layer->scaleImage(350,0);
}
//rotate image
$layer->rotateImage(new ImagickPixel("none"), $angle);
//Merge Image
if($this->id == 44){
$base->compositeImage($layer, imagick::COMPOSITE_OVER, $x, $y);
}else{
$base->compositeImage($layer, imagick::COMPOSITE_DEFAULT, $x, $y);
}
$this->image = $base;
}
}
The the test is currently been run when $this->id uses 44.
Can anyone shed light on this issue?
Thanks in advance

Answer 1

You need to use imagecolortransparent in order to have transparency capabilities.
N.B. JPG does not have transparent properties, only PNG and GIF files (and TIFF) but browsers do not support that format.
Your output file will need to be converted to one of those formats, preferably PNG then set the transparency for the desired color.
"so would you suggest converting to PNG then rotating? then merging the PNG image into the JPG (if it is possible) as the image output is required to be a jpg"
You will lose transparency as soon as you resave as JPG

Answer 2

I came across this via Google, here's the correct answer as others may find it. You need to use setImageMatte(1) to enable the transparency, e.g.
$src->setImageMatte(1);
$mask->rotateImage(new ImagickPixel('#00000000'), 10);
You may also use an image Mask, where black will become transparent using
$src->compositeImage($mask, Imagick::COMPOSITE_DSTIN, 0, 0, Imagick::CHANNEL_ALPHA);