[PHP] Image manipulation on the fly
Hi there,
I need to manipulate images on the fly. My goal is to make the image
very bright, or to add a sepia effect. The problem is, that this takes a
lot of computing power on 1024 pictures. About 2s on my server until the
image is delivered.
Does anybody know a high performing image funtion that would allow me to
brighten up the picture on the fly, or any other effect similar to it?
I am attaching the sepia function I am using.
Thank you for any help or suggestion on how to solve that.
Best regards,
Merlin
function image_effect_sepia($im){
$start_red = 2; //red scale at black
$start_blue = 2.3; //blue scale at black
$red_scale = ($start_red-1)/256;//red modifier as
greyscale goes to white
$blue_scale = ($start_blue - 1)/256;//ditto for blue
//build a sepia lookup table
$sepia = array();
for($x = 0;$x 256;$x++){
$red = intval($x * ($start_red - ($x * $red_scale)));
if($red 255) $red = 255;
$blue = intval($x / ($start_blue - ($x * $blue_scale)));
$sepia[$x][0] = $red;
$sepia[$x][1] = $blue;
}
# modify the image
for($y = 0;$y imagesy($im);$y++){
for($x = 0;$x imagesx($im);$x++){
$pixel = imagecolorat($im, $x, $y);
$red = ($pixel 0xFF) 16;
$green = ($pixel 0x00FF00) 8;
$blue = $pixel 0xFF;
$alpha = $pixel 0x7F00;
//get a greyscale value
$gs = intval(($red * 0.3) + ($green * 0.59) + ($blue * 0.11));
$p = $alpha | $sepia[$gs][1] | ($gs 8) | ($sepia[$gs][0]
16);
imagesetpixel ($im, $x, $y, $p);
}
}
# return the moddifyed image
return $im;
}
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Re: [PHP] Image manipulation on the fly
Hi Merlin, that is very fast for 1024 images, you will not get much
more speed if you try doing anything smarter ,
though there are some image libraries that are faster than GD libs eg
www.imagemagick.org
On Nov 8, 2007, at 5:13 PM, Merlin wrote:
Hi there,
I need to manipulate images on the fly. My goal is to make the image
very bright, or to add a sepia effect. The problem is, that this
takes a lot of computing power on 1024 pictures. About 2s on my
server until the image is delivered.
Does anybody know a high performing image funtion that would allow
me to brighten up the picture on the fly, or any other effect
similar to it?
I am attaching the sepia function I am using.
Thank you for any help or suggestion on how to solve that.
Best regards,
Merlin
function image_effect_sepia($im){
$start_red = 2; //red scale at black
$start_blue = 2.3; //blue scale at black
$red_scale = ($start_red-1)/256;//red modifier
as greyscale goes to white
$blue_scale = ($start_blue - 1)/256;//ditto for blue
//build a sepia lookup table
$sepia = array();
for($x = 0;$x 256;$x++){
$red = intval($x * ($start_red - ($x * $red_scale)));
if($red 255) $red = 255;
$blue = intval($x / ($start_blue - ($x * $blue_scale)));
$sepia[$x][0] = $red;
$sepia[$x][1] = $blue;
}
# modify the image
for($y = 0;$y imagesy($im);$y++){
for($x = 0;$x imagesx($im);$x++){
$pixel = imagecolorat($im, $x, $y);
$red = ($pixel 0xFF) 16;
$green = ($pixel 0x00FF00) 8;
$blue = $pixel 0xFF;
$alpha = $pixel 0x7F00;
//get a greyscale value
$gs = intval(($red * 0.3) + ($green * 0.59) + ($blue *
0.11));
$p = $alpha | $sepia[$gs][1] | ($gs 8) | ($sepia[$gs]
[0] 16);
imagesetpixel ($im, $x, $y, $p);
}
}
# return the moddifyed image
return $im;
}
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Bojan Tesanovic
http://www.classicio.com/
Re: [PHP] Image manipulation on the fly
Merlin wrote: Hi there, I need to manipulate images on the fly. My goal is to make the image very bright, or to add a sepia effect. The problem is, that this takes a lot of computing power on 1024 pictures. About 2s on my server until the image is delivered. Yeah, you're doing CPU-intensive stuff in an interpreted language - it'll never be efficient unless you write it in C or similar. /Per Jessen, Zürich -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
