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imagefontheight> <imagefilltoborder
[edit] Last updated: Fri, 10 Feb 2012

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imagefilter

(PHP 5)

imagefilter — Applique un filtre à une image

Description

bool imagefilter ( resource $image , int $filtertype [, int $arg1 [, int $arg2 [, int $arg3 [, int $arg4 ]]]] )

imagefilter() applique le filtre filtertype à l'image en utilisant les paramètres args1, args2 et args3 lorsque cela est nécessaire.

Liste de paramètres

image

Une ressource d'image, retournée par une des fonctions de création d'images, comme imagecreatetruecolor().

filtertype

Le paramètre filtertype peut prendre l'une des valeurs suivantes :

  • IMG_FILTER_NEGATE : renverse toutes les couleurs de l'image.
  • IMG_FILTER_GRAYSCALE : convertit l'image en grayscale.
  • IMG_FILTER_BRIGHTNESS : modifie la luminosité de l'image. Utilisez le paramètre args1 pour définir la luminosité.
  • IMG_FILTER_CONTRAST : modifie le contraste de l'image. Utilisez le paramètre args1 pour définir le contraste.
  • IMG_FILTER_COLORIZE : identique au paramètre IMG_FILTER_GRAYSCALE excepté que vous pouvez spécifier une couleur. Utilisez trois arguments séparés dans les paramètres args1, args2 et args3 sous la forme red, blue, green et arg4 pour le canal alpha. L'intervalle pour chaque couleur est 0 - 255.
  • IMG_FILTER_EDGEDETECT : utilise la détection des bords pour les mettre en évidence dans l'image.
  • IMG_FILTER_EMBOSS : grave l'image en relief.
  • IMG_FILTER_GAUSSIAN_BLUR : brouille l'image en utilisant la méthode gaussienne.
  • IMG_FILTER_SELECTIVE_BLUR : brouille l'image.
  • IMG_FILTER_MEAN_REMOVAL : son utilisation signifie le déplacement pour réaliser un effet "peu précis".
  • IMG_FILTER_SMOOTH : rend l'image lissée (smooth). Utilisez le paramètre args1 pour définir le degré de lissoir.
  • IMG_FILTER_PIXELATE : applique un effet de pixelisation à l'image; utilise arg1 pour indiquer la taille de bloc, et arg2 pour indiquer le mode de pixelisation.

arg1

  • IMG_FILTER_BRIGHTNESS : degré de luminosité.
  • IMG_FILTER_CONTRAST : degré du contraste.
  • IMG_FILTER_COLORIZE : Valeur du composant rouge.
  • IMG_FILTER_SMOOTH : degré du lissé.
  • IMG_FILTER_PIXELATE: taille de bloc en pixels.

arg2

  • IMG_FILTER_COLORIZE : Valeur du composant vert.

arg3

  • IMG_FILTER_COLORIZE : Valeur du composant bleu.

arg4

  • IMG_FILTER_COLORIZE : canal Alpha. Une valeur entre 0 et 127. 0 signifie totalement opaque, tandis que 127 signifie totalement transparent.
  • IMG_FILTER_PIXELATE: s'il faut utiliser un effet de pixelisation avancé ou non (par défaut, FALSE).

Valeurs de retour

Cette fonction retourne TRUE en cas de succès ou FALSE si une erreur survient.

Historique

Version Description
5.3.0 Support de la pixelisation (IMG_FILTER_PIXELATE) ajouté.
5.2.5 Le support du canal Alpha pour la constante IMG_FILTER_COLORIZE a été ajouté.

Exemples

Exemple #1 Exemple avec imagefilter()

<?php
$im = imagecreatefrompng('dave.png');

if($im && imagefilter($im, IMG_FILTER_GRAYSCALE))
{
    echo 'Image convertie en grayscale.';

    imagepng($im, 'dave.png');
}
else
{
    echo 'La conversion en grayscale a échoué.';
}

imagedestroy($im);
?>

Exemple #2 Exemple avec imagefilter()

<?php
$im = imagecreatefrompng('sean.png');

if($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20))
{
    echo 'La luminosité de l\'image a été modifiée.';
    imagepng($im, 'sean.png');
    imagedestroy($im);
}
else
{
    echo 'Echec lors de la modification de la luminosité.';
}
?>

Exemple #3 Exemple avec imagefilter()

<?php
$im = imagecreatefrompng('philip.png');

/* R, G, B, donc 0, 255, 0 correspond au vert */
if($im && imagefilter($im, IMG_FILTER_COLORIZE, 0, 255, 0))
{
    echo 'L\'image a été ombragée en vert avec succès.';
    imagepng($im, 'philip.png');
    imagedestroy($im);
}
else
{
    echo 'Echec lors de la modification de l\'ombrage.';
}
?>

Exemple #4 Exemple d'image en négatif avec imagefilter()

<?php
// Définition de notre fonction "négatif" afin qu'elle soit portable
// également sur les versions de PHP qui n'ont pas la fonction imagefilter()
function negate($im)
{
    if(function_exists('imagefilter'))
    {
        return imagefilter($im, IMG_FILTER_NEGATE);
    }

    for($x = 0; $x < imagesx($im); ++$x)
    {
        for($y = 0; $y < imagesy($im); ++$y)
        {
            $index = imagecolorat($im, $x, $y);
            $rgb = imagecolorsforindex($index);
            $color = imagecolorallocate($im, 255 - $rgb['red'], 255 - $rgb['green'], 255 - $rgb['blue']);

            imagesetpixel($im, $x, $y, $color);
        }
    }

    return(true);
}

$im = imagecreatefromjpeg('kalle.jpg');

if($im && negate($im))
{
    echo 'Image convertie avec succès en couleur négative.';

    imagejpeg($im, 'kalle.jpg', 100);
    imagedestroy($im);
}
else
{
    echo 'Echec lors de la conversion en couleur négative.';
}
?>

Exemple #5 Exemple de pixelisation avec imagefilter()

<?php
// Chargement du logo PH, nous avons besoin de deux instances.
$logo1 = imagecreatefrompng('./php.png');
$logo2 = imagecreatefrompng('./php.png');

// Crée une image sur laquelle nous voulons montrer les différences
$output = imagecreatetruecolor(imagesx($logo1) * 2, imagesy($logo1));

// Applique la pixelation à chaque instances, avec un bloc de 3
imagefilter($logo1, IMG_FILTER_PIXELATE, 3);
imagefilter($logo2, IMG_FILTER_PIXELATE, 3, true);

// Fusion des différences dans l'image finale
imagecopy($output, $logo1, 0, 0, 0, 0, imagesx($logo1) - 1, imagesy($logo1) - 1);
imagecopy($output, $logo2, imagesx($logo2), 0, 0, 0, imagesx($logo2) - 1, imagesy($logo2) - 1);
imagedestroy($logo1);
imagedestroy($logo2);

// Affichage des différences
header('Content-Type: image/png');
imagepng($output);
imagedestroy($output);
?>

L'exemple ci-dessus va afficher quelque chose de similaire à :

Affichage de l'exemple : imagefilter()

Notes

Note: Cette fonction n'est disponible que si PHP est compilé avec la version embarquée de la bibliothèque GD.

Voir aussi

  • imageconvolution() - Applique une matrice de la convolution 3x3, en utilisant le coefficient et l'excentrage



imagefontheight> <imagefilltoborder
[edit] Last updated: Fri, 10 Feb 2012
 
add a note add a note User Contributed Notes imagefilter
mail at pedrocandeias dot com 29-Oct-2011 07:20
// With transparent PNG file you can colorize the "positive" items and stand the transparent has it is - Beta code

<?php
header('Content-Type: image/png');

$im = imagecreatefrompng('image.png');
$width = imagesx($im);
$height = imagesy($im);
$imn = imagecreatetruecolor($width, $height);
imagealphablending($imn,false);
$col=imagecolorallocatealpha($imn,255,255,255,127);
imagesavealpha($imn,true);
imagefilledrectangle($imn,0,0,$width,$height,$col);
imagealphablending($imn,true);
imagecopy($imn, $im, 0, 0, 0, 0, $width, $height);
imagefilter($imn, IMG_FILTER_NEGATE);

// FOR A TRANSPARENT PNG FILE WITH SOMETHING INSIDE, YOU CAN CHANGE THE COLOR HERE: I HAVE RGB: 0, 255, 0
imagefilter($imn, IMG_FILTER_COLORIZE, 0, 255, 0);

imagepng($imn);
imagedestroy($imn);

?>
hadrien dot jouet at grownseed dot net 21-Jun-2011 06:58
For people looking to apply a 'multiply' effect on images like the one in Photoshop (generally b&w ones), you can achieve it with the IMG_FILTER_COLORIZE filter.

<?php
function multiplyColor(&$im, $color = array(255, 0, 0))
{
   //get opposite color
   $opposite = array(255 - $color[0], 255 - $color[1], 255 - $color[2]);

   //now we subtract the opposite color from the image
   imagefilter($im, IMG_FILTER_COLORIZE, -$opposite[0], -$opposite[1], -$opposite[2]);
}
?>
bushmakin stas (bushstas at mail dot ru) 17-Mar-2011 12:26
a function to make all colors gray except the only one
i made it myself so the code is note so beautiful )

<?php
function imagecolorfilter($im){
   
    $height = imagesy($im);
    $width = imagesx($im);
    for($x=0; $x<$width; $x++){
        for($y=0; $y<$height; $y++){
            $rgb = ImageColorAt($im, $x, $y);
            $r = ($rgb >> 16) & 0xFF;
            $g = ($rgb >> 8) & 0xFF;
            $b = $rgb & 0xFF;
            $c=($r+$g+$b)/3;
           
//if($g<$r || $g<$b+20){$r=$c;$g=$c; $b=$c;}//leaves only green
//if($b<$r || $b<$g){$r=$c;$g=$c; $b=$c;}//only blue
if($r<$g+30 || $r<$b){$r=$c;$g=$c; $b=$c;}//only red
//if($r<$g-1 || $r>$g+60 || $b>$g-50){$r=$c;$g=$c; $b=$c;}//only yellow
           
           
imagesetpixel($im, $x, $y,imagecolorallocate($im, $r,$g,$b));
        }
    }
}

header ("Content-type: image/jpeg");
$im = imagecreatefromjpeg("image.jpg");
imagecolorfilter($im);
imagejpeg($im);
?>
jonathan dot gotti at gmail dot com 30-Nov-2010 06:38
IMG_FILTER_COLORIZE doesn't seem to work on palette image, here's a way to achieve same result with palette image:

<?php
//$color is an array containing rvb infos (ie: array(255,80,0))
function paletteColorize($imgResource,array $color){
    $nbColors = imagecolorstotal($imgResource);
    for($i=0; $i<$nbColors; $i++){
        $c = array_values(imagecolorsforindex($imgRes,$i));
        for($y=0;$y<3;$y++)
            $c[$y] = max(0,min(255,$c[$y]+$color[$y]));
        imagecolorset($imgResource,$i,$c[0],$c[1],$c[2]);
    }
}
?>

Here's also a function that work on both truecolor and palette images that try to do something similar to greyscale with a given color
<?php
function colorScale($imgRes,array $color){
        imagefilter($imgRes,IMG_FILTER_GRAYSCALE);
        $color = self::_read_color($color);
        $luminance=($color[0]+$color[1]+$color[2])/3; // average luminance added by the color
        $brightnessCorrection = $luminance/3; // quantity of brightness to correct for each channel
        if( $luminance < 127 ){
            $brightnessCorrection -= 127/3; // color is dark so we have to negate the brightness correction
        }
        if(! imageistruecolor($imgRes) ){
            $nbColors = imagecolorstotal($imgRes);
            for($i=0; $i<$nbColors; $i++){
                $c = array_values(imgagecolorsforindex($imgRes,$i));
                for($y=0;$y<3;$y++){
                    $c[$y] = max(0, min(255, $c[$y] + ($color[$y]-$luminance) + $brightnessCorrection) ); // parentheses just for better comprehension
                }
                imagecolorset($omgRes,$i,$c[0],$c[1],$c[2]);
            }
        }else{ // much easier with truecolor
            imagefilter($imgRes, IMG_FILTER_COLORIZE, $color[0]-$luminance, $color[1]-$luminance, $color[2]-$luminance);
            imagefilter($imgRes, IMG_FILTER_BRIGHTNESS, $brightnessCorrection);
        }
}
?>

with hope that someone will find this useful
mail at kavisiegel dot com 25-Jun-2009 11:11
Searching for a way to easily change the color of the image, I tried IMG_FILTER_COLORIZE. I was unable to get the quality results I wanted. It turns out PHP's Colorize is the equivalent of Photoshop's "Linear Dodge" layer filter.

Hue adjustments have always worked well for me, so I figured I could try with PHP.
This function is kind of slow on larger images, but on small images like what I'm using it for, the difference is trivial.

The script calculates the ratio or red, to green, to blue in the color provided, then scales the image appropriately... unfortunately, it does it pixel by pixel.

Here's a demo and comparison of this function, to photoshop's hue function, to PHP's colorize. http://img146.imageshack.us/img146/3167/imagefilterhuedemo.png

<?php
function imagefilterhue($im,$r,$g,$b){
    $rgb = $r+$g+$b;
    $col = array($r/$rgb,$b/$rgb,$g/$rgb);
    $height = imagesy($im);
    $width = imagesx($im);
    for($x=0; $x<$width; $x++){
        for($y=0; $y<$height; $y++){
            $rgb = ImageColorAt($im, $x, $y);
            $r = ($rgb >> 16) & 0xFF;
            $g = ($rgb >> 8) & 0xFF;
            $b = $rgb & 0xFF;
            $newR = $r*$col[0] + $g*$col[1] + $b*$col[2];
            $newG = $r*$col[2] + $g*$col[0] + $b*$col[1];
            $newB = $r*$col[1] + $g*$col[2] + $b*$col[0];
            imagesetpixel($im, $x, $y,imagecolorallocate($im, $newR, $newG, $newB));
        }
    }
}
header ("Content-type: image/jpeg");
$im = imagecreatefromjpeg("test.jpg");

// Usage: Just as imagefilter(), except with no filtertype.
// imagefilterhue(resource $image, int $red, int $green , int $blue)
imagefilterhue($im,2,70,188);

// The equivalent with colorize, as tested in demo image: imagefilter($im, IMG_FILTER_COLORIZE, 2, 70, 188);

imagejpeg($im);
?>
aiden dot mail at freemail dot hu 29-Mar-2008 12:16
Function to change the transparency of a png image on the fly. Works only with PNG, and with a browser supporting alpha channel.
The function stretches the opacity-range of the image, so that the most opaque pixel(s) will be set to the given opacity. (Other opacity values in pixels are modified accordingly.)
Returns success or failure.

<?php
function filter_opacity( &$img, $opacity ) //params: image resource id, opacity in percentage (eg. 80)
        {
            if( !isset( $opacity ) )
                { return false; }
            $opacity /= 100;
           
            //get image width and height
            $w = imagesx( $img );
            $h = imagesy( $img );
           
            //turn alpha blending off
            imagealphablending( $img, false );
           
            //find the most opaque pixel in the image (the one with the smallest alpha value)
            $minalpha = 127;
            for( $x = 0; $x < $w; $x++ )
                for( $y = 0; $y < $h; $y++ )
                    {
                        $alpha = ( imagecolorat( $img, $x, $y ) >> 24 ) & 0xFF;
                        if( $alpha < $minalpha )
                            { $minalpha = $alpha; }
                    }
           
            //loop through image pixels and modify alpha for each
            for( $x = 0; $x < $w; $x++ )
                {
                    for( $y = 0; $y < $h; $y++ )
                        {
                            //get current alpha value (represents the TANSPARENCY!)
                            $colorxy = imagecolorat( $img, $x, $y );
                            $alpha = ( $colorxy >> 24 ) & 0xFF;
                            //calculate new alpha
                            if( $minalpha !== 127 )
                                { $alpha = 127 + 127 * $opacity * ( $alpha - 127 ) / ( 127 - $minalpha ); }
                            else
                                { $alpha += 127 * $opacity; }
                            //get the color index with new alpha
                            $alphacolorxy = imagecolorallocatealpha( $img, ( $colorxy >> 16 ) & 0xFF, ( $colorxy >> 8 ) & 0xFF, $colorxy & 0xFF, $alpha );
                            //set pixel with the new color + opacity
                            if( !imagesetpixel( $img, $x, $y, $alphacolorxy ) )
                                { return false; }
                        }
                }
            return true;
        }
?>

Example for use:

 <?php
  $image = imagecreatefrompng( "img.png" );
  filter_opacity( $image, 75 );
  header( "content-type: image/png" );
  imagepng( $image );
  imagedestroy( $image );
?>
Kae Cyphet 02-Dec-2007 04:23
To solve that annoying problem of having to install a pre-compiled version of GD just to get imagefilter($image,IMAGE_FILTER_NEGATE) working.

here is an open source solution.
uses the standard stuff included in php when you uncomment 'extension=php_gd2.dll' in the php.ini file and there ya go!

Useage:
<?php
$im = imagecreatefromjpeg("my_fav_image.jpg");

header("Content-type: image/jpg");
imagejpeg(invertimage($im));

imagedestroy($im);
?>

'=================================

<?php
function int2rgb($myint)
{
  return array('red' => 0xFF & ($myint >> 0x10), 'green' => 0xFF & ($myint >> 0x8), 'blue' => 0xFF & $myint);
}

function invertimage($im)
{
 $wid = imagesx($im);
 $hei = imagesy($im);
 $im2 = imagecreatetruecolor($wid,$hei);
 $i=0;
 $j=0;
 $rgb = array('red' => 0, 'green' => 0, 'blue' => 0);
 $ref = 0;

 for($i = 0;$i < $wid; $i++)
 {
  for($j = 0;$j < $hei; $j++)
  {
   $rgb = int2rgb(imagecolorat($im,$i,$j));
   $ref = imagecolorallocate($im2,255 - intval($rgb['red']),255 - intval($rgb['green']),255 - intval($rgb['blue']));
   imagesetpixel($im2,$i,$j,$ref);
  }
 }
 return $im2;
}
?>
michaeln no at spam associationsplus ca 21-Nov-2007 08:11
Note: applying IMG_FILTER_EMBOSS to text and using in a customization to the CAPTCHA image script in phpBB or a project of your own is a very good way to stop OCR-ing bots from getting through. Embossed serif fonts are fairly easy for the human eye to understand but to an OCR script it is extremely difficult because it seems to give it the illusion of 3D.

If you only allocate 2 or 3 colours in the image, it uses the background colour alot in the embossed text, which greatly contributes to this.

I made my own custom CAPTCHA script to stop phpBB post spam for a client site I was developing and I have gone from getting 2-3 new spam users created every day to zero.

Anything with the source code freely available out there right now is possible to be defeated by spammers once one of them stars sharing code with the other spammers, but if you run something at least someone custom, their bots will pass you over.
ssttoo at gmail dot com 13-Nov-2007 12:31
Here's a page that shows the different filters in action
http://www.phpied.com/image-fun-with-php-part-2/
Also shows some quick ways to do sepia.
admin at phpgfx dot com 26-Aug-2007 09:52
this is a sepia function using microsoft's definition

<?php

function imagesepia( $img ) {
    $total = imagecolorstotal( $img );
    for ( $i = 0; $i < $total; $i++ ) {
        $index = imagecolorsforindex( $img, $i );
        $red = ( $index["red"] * 0.393 + $index["green"] * 0.769 + $index["blue"] * 0.189 ) / 1.351;
        $green = ( $index["red"] * 0.349 + $index["green"] * 0.686 + $index["blue"] * 0.168 ) / 1.203;
        $blue = ( $index["red"] * 0.272 + $index["green"] * 0.534 + $index["blue"] * 0.131 ) / 2.140;
        imagecolorset( $img, $i, $red, $green, $blue );
    }
}

?>
webmaster at designsbykosi dot info 08-May-2007 12:56
This will only work if you have php5. For php4, you'll have to use the sepia function set webmaster at qudi dot de suggested.
fananf at nerdshack dot com 16-Mar-2007 09:26
If you're looking for fast sepia effect that can be used for on-the-fly thumbnails generation you can't use sophisticated functions. The faster and much better way than described by webmaster at qudi dot de in the note from 31-Jan-2006 is applying colorize filter AFTER grayscale.

<?php

(...)

imagefilter($yourimage, IMG_FILTER_GRAYSCALE); imagefilter($yourimage, IMG_FILTER_COLORIZE, 90, 60, 40);

(...)

?>

I used (90,60,40) for my sepia after couple of tests, however, if you need darker or lighter just check what suits you best.
trucex email over at gmail 14-Feb-2007 12:31
It appears that imagefilter doesn't play nice with apha. If you run an imagefilter on a transparent image it'll return a black image...similar to a lot of Photoshop plugins do.
PanuWorld 14-Jan-2007 06:55
The documentation misses the exact meaning and valid ranges of the arguments for ImageFilter(). According to the 5.2.0 sources the arguments are:
IMG_FILTER_BRIGHTNESS
-255 = min brightness, 0 = no change, +255 = max brightness

IMG_FILTER_CONTRAST
-100 = max contrast, 0 = no change, +100 = min contrast (note the direction!)

IMG_FILTER_COLORIZE
Adds (subtracts) specified RGB values to each pixel. The valid range for each color is -255...+255, not 0...255. The correct order is red, green, blue.
-255 = min, 0 = no change, +255 = max
This has not much to do with IMG_FILTER_GRAYSCALE.

IMG_FILTER_SMOOTH
Applies a 9-cell convolution matrix where center pixel has the weight arg1 and others weight of 1.0. The result is normalized by dividing the sum with arg1 + 8.0 (sum of the matrix).
any float is accepted, large value (in practice: 2048 or more) = no change

ImageFilter seem to return false if the argument(s) are out of range for the chosen filter.
nancy at hypertextdigital dot com 03-Aug-2006 02:16
This routine was just what I was looking for, I wanted web admin users to be able to recolour their uploaded photos (to go with a news item) either a blue tint or sepia to match the appearance of other colours used on the website.

Using a form with a select box containing the RGB values, I can give them the option of either of the two tints or no colourization at all, plus resize their images to the viewing size and a thumbnail image on the fly without having to use any other image editing software.
santibari at fibertel dot com 27-Feb-2006 11:37
A colorize algorithm wich preserves color luminosity (i.e black
will output black, and white will output white).
This works in PHP4 and is great for customizing interfaces
dinamically.

<?php
function colorize($img_src,$img_dest, $r, $g, $b)
{
if(!$im = imagecreatefromgif($img_src))
  return "Could not use image $img_src";
   
//We will create a monochromatic palette based on
//the input color
//which will go from black to white
//Input color luminosity: this is equivalent to the
//position of the input color in the monochromatic
//palette
$lum_inp=round(255*($r+$g+$b)/765); //765=255*3

//We fill the palette entry with the input color at its
//corresponding position

$pal[$lum_inp]['r']=$r;
$pal[$lum_inp]['g']=$g;
$pal[$lum_inp]['b']=$b;

//Now we complete the palette, first we'll do it to
//the black,and then to the white.

//FROM input to black
//===================
//how many colors between black and input
$steps_to_black=$lum_inp;       

//The step size for each component
if($steps_to_black)
 {
 $step_size_red=$r/$steps_to_black;   
 $step_size_green=$g/$steps_to_black;   
 $step_size_blue=$b/$steps_to_black;   
 }

for($i=$steps_to_black;$i>=0;$i--)
 {
 $pal[$steps_to_black-$i]['r']=$r-round($step_size_red*$i);
 $pal[$steps_to_black-$i]['g']=$g-round($step_size_green*$i);
 $pal[$steps_to_black-$i]['b']=$b-round($step_size_blue*$i);
 }

//From input to white:
//===================
//how many colors between input and white
$steps_to_white=255-$lum_inp;

if($steps_to_white)
  {
  $step_size_red=(255-$r)/$steps_to_white;   
  $step_size_green=(255-$g)/$steps_to_white;   
  $step_size_blue=(255-$b)/$steps_to_white;   
  }
 else
  $step_size_red=$step_size_green=$step_size_blue=0;

 //The step size for each component
 for($i=($lum_inp+1);$i<=255;$i++)
  {
  $pal[$i]['r']=$r + round($step_size_red*($i-$lum_inp));
  $pal[$i]['g']=$g + round($step_size_green*($i-$lum_inp));
  $pal[$i]['b']=$b + round($step_size_blue*($i-$lum_inp));
  }
//--- End of palette creation

//Now,let's change the original palette into the one we
//created
for($c = 0; $c < $palette_size; $c++)
 {
 $col = imagecolorsforindex($im, $c);         
 $lum_src=round(255*($col['red']+$col['green']
                +$col['blue'])/765);
 $col_out=$pal[$lum_src];
 imagecolorset($im, $c, $col_out['r'],
                                $col_out['g'],
                                $col_out['b']);
 }

 //save the image file
 imagepng($im,$img_dest);
 imagedestroy($im);
}//end function colorize
?>
webmaster at qudi dot de 31-Jan-2006 06:53
for a quick, ok-looking, sepia-effect (also in php4) I just use this little fellow, since a real implementation of sepia was just way too slow.

function pseudosepia(&$im,$percent){
      $sx=imagesx($im);
      $sy=imagesy($im);
      $filter=imagecreatetruecolor($sx,$sy);
      $c=imagecolorallocate($filter,100,50,50);
      imagefilledrectangle($filter,0,0,$sx,$sy,$c);
      imagecopymerge($im,$filter,0,0,0,0,$sx,$sy,$percent);
}
a php user at nowhere dot com 20-Dec-2005 12:48
http://www.hudzilla.org/phpbook/read.php/11_2_15
for more detailed info, and some <i>arg</i> guidelines.
vdepizzol at hotmail dot com 04-Sep-2004 01:36
Examples using imagefilter():

<?php
$im = imagecreatefrompng('dave.png');
if ($im && imagefilter($im, IMG_FILTER_GRAYSCALE)) {
    echo 'Image converted to grayscale.';
    imagepng($im, 'dave.png');
} else {
    echo 'Conversion to grayscale failed.';
}

imagedestroy($im);
?>

/////////////////////////////

<?php
$im = imagecreatefrompng('sean.png');
if ($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20)) {
    echo 'Image brightness changed.';
    imagepng($im, 'sean.png');
} else {
    echo 'Image brightness change failed.';
}

imagedestroy($im);
?>

/////////////////////////////

<?php
$im = imagecreatefrompng('philip.png');

/* R, G, B, so 0, 255, 0 is green */
if ($im && imagefilter($im, IMG_FILTER_COLORIZE, 0, 255, 0)) {
    echo 'Image successfully shaded green.';
    imagepng($im, 'philip.png');
} else {
    echo 'Green shading failed.';
}

imagedestroy($im);
?>
kees at tweakers dot net 20-Jul-2004 06:26
From what i have been able to find from this function, it accepts the following arguments:
        IMG_FILTER_NEGATE
        IMG_FILTER_GRAYSCALE
        IMG_FILTER_EDGEDETECT
        IMG_FILTER_GAUSSIAN_BLUR
        IMG_FILTER_SELECTIVE_BLUR
        IMG_FILTER_EMBOSS
        IMG_FILTER_MEAN_REMOVAL

The following arguments need one or more arguments.
        IMG_FILTER_SMOOTH, -1924.124
        IMG_FILTER_COLORIZE, -127.12, -127.98, 127
        IMG_FILTER_CONTRAST, -90
        IMG_FILTER_BRIGHTNESS, 98
       
I haven't tested them all, the names speak for themselves.
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