[edit] Last updated: Fri, 17 May 2013

imagefilter

(PHP 5)

imagefilter — Aplica un filtro a una imagen

Descripción

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

imagefilter() aplica el filtro filtertype dado sobre image.

Parámetros

image

Un recurso image, es devuelto por una de las funciones de creación de imágenes, como imagecreatetruecolor().

filtertype

filtertype puede ser uno de los siguitentes:

IMG_FILTER_NEGATE: Invierte todos los colores de la imagen.
IMG_FILTER_GRAYSCALE: Convierte la imagen en escala de grises.
IMG_FILTER_BRIGHTNESS: Cambia el brillo de la imagen. Use arg1 para establecer el nivel de brillo.
IMG_FILTER_CONTRAST: Cambia el contraste de la imagen. Use arg1 para establecer el nivel de contraste.
IMG_FILTER_COLORIZE: Como IMG_FILTER_GRAYSCALE, excepto que se puede especificar el color. Use arg1, arg2 y arg3 en la forma red, green, blue y arg4 para el canal alpha. El rango de cada color es de 0 a 255.
IMG_FILTER_EDGEDETECT: Usa detección de borde para resaltar los bordes de la imagen.
IMG_FILTER_EMBOSS: Pone en relieve la imagen.
IMG_FILTER_GAUSSIAN_BLUR: Pone borrosa la imagen usando el método Gaussiano.
IMG_FILTER_SELECTIVE_BLUR: Pone borrosa la imagen.
IMG_FILTER_MEAN_REMOVAL: Utiliza eliminación media para lograr un efecto "superficial".
IMG_FILTER_SMOOTH: Suaviza la imagen. Use arg1 para esteblecer el nivel de suavidad.
IMG_FILTER_PIXELATE: Aplica el efecto de pixelación a la imagen, use arg1 para establecer el tamaño de bloque y arg2 para establecer el modo de efecto de pixelación.

arg1

IMG_FILTER_BRIGHTNESS: Nivel de brillo.
IMG_FILTER_CONTRAST: Nivel de contraste.
IMG_FILTER_COLORIZE: Valor del componente rojo.
IMG_FILTER_SMOOTH: Nivel de suavidad.
IMG_FILTER_PIXELATE: Tamaño de bloque en píxeles.

arg2

IMG_FILTER_COLORIZE: Valor del componente verde.
IMG_FILTER_PIXELATE: Si usar o no el efecto de pixelación avanzado (por defecto a FALSE).

arg3

IMG_FILTER_COLORIZE: Valor del componente azul.

arg4

IMG_FILTER_COLORIZE: Canal alfa. Un valor entre 0 y 127. 0 indica completamente opaco mientras que 127 indica completamente transparente.

Valores devueltos

Devuelve TRUE en caso de éxito o FALSE en caso de error.

Historial de cambios

Versión	Descripción
5.3.0	Se añadió el soporete de pixelación (`IMG_FILTER_PIXELATE`).
5.2.5	Se añadió el soporte de alfa para `IMG_FILTER_COLORIZE`.

Ejemplos

Ejemplo #1 Ejemplo de escala de grises con imagefilter()


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

if($im && imagefilter($im, IMG_FILTER_GRAYSCALE))
{
    echo 'Imagen convertida a escala de grises.';

    imagepng($im, 'dave.png');
}
else
{
    echo 'La conversión a escala de grises falló.';
}

imagedestroy($im);
?>

Ejemplo #2 Ejemplo de brillo con imagefilter()


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

if($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20))
{
    echo 'Brillo de la imagen cambiado.';

    imagepng($im, 'sean.png');
    imagedestroy($im);
}
else
{
    echo 'El cambio del brillo de la imagen falló.';
}
?>

Ejemplo #3 Ejemplo de coloración con imagefilter()


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

/* R, G, B, así 0, 255, 0 es verde */
if($im && imagefilter($im, IMG_FILTER_COLORIZE, 0, 255, 0))
{
    echo 'Imagen sombreada a verde con éxito.';

    imagepng($im, 'philip.png');
    imagedestroy($im);
}
else
{
    echo 'El sombreado a verde falló.';
}
?>

Ejemplo #4 Ejemplo de inversión de color con imagefilter()


<?php
// Define nuestra función negativo, así es portable para
// versiones de php sin imagefilter()
function negativo($im)
{
    if(function_exists('imagefilter'))
    {
        return imagefilter($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($im && negativo($im))
{
    echo 'Imagen convertida a colores negativos con éxtito.';

    imagejpeg($im, 'kalle.jpg', 100);
    imagedestroy($im);
}
else
{
    echo 'La conversión a colores negativos falló.';
}
?>

Ejemplo #5 Ejemplo de pixelación con imagefilter()


<?php
// Cargar el logotipo de PHP, necesitamos crear dos instancias
// para mostrar las diferencias
$logo1 = imagecreatefrompng('./php.png');
$logo2 = imagecreatefrompng('./php.png');

// Crear la instancia de imagen que queremos para mostrar
// las diferencias
$salida = imagecreatetruecolor(imagesx($logo1) * 2, imagesy($logo1));

// Aplicar pixelación a cada instancia, con un tamaño de
// bloque de 3
imagefilter($logo1, IMG_FILTER_PIXELATE, 3);
imagefilter($logo2, IMG_FILTER_PIXELATE, 3, true);

// Fusionar las diferencias a la imagen de salida
imagecopy($salida, $logo1, 0, 0, 0, 0, imagesx($logo1) - 1, imagesy($logo1) - 1);
imagecopy($salida, $logo2, imagesx($logo2), 0, 0, 0, imagesx($logo2) - 1, imagesy($logo2) - 1);
imagedestroy($logo1);
imagedestroy($logo2);

// Imprimir las diferencias
header('Content-Type: image/png');
imagepng($salida);
imagedestroy($salida);
?>

El resultado del ejemplo sería algo similar a:

Notas

Nota: Esta función sólo está disponible si PHP fue compilado con la versión incluida de GD library.

Ver también

imageconvolution() - Aplicar una matriz de convolución de 3x3, usando coeficiente e índice

imageflip

imagefilltoborder

[edit] Last updated: Fri, 17 May 2013

add a note User Contributed Notes imagefilter - [23 notes]

down

bushmakin stas (bushstas at mail dot ru) ¶

2 years ago


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);


?>

down

jonathan dot gotti at gmail dot com ¶

2 years ago


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

down

aiden dot mail at freemail dot hu ¶

5 years ago


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 );

?>

down

michaeln no at spam associationsplus ca ¶

5 years ago


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.

down

PanuWorld ¶

6 years ago


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.

down

Padde ¶

5 months ago


I played with IMG_FILTER_SMOOTH and tried some negative

values.



-1 to -7: looks like a mix of smoothness and edgedetect



-8: image seems to be completely broken



-9 and lower: kind of sharpening effect (-9 sharper than -10)



I think the sharpening effect in particular could be useful.

down

martijn(97+1) at gmail dot com (solve math) ¶

7 months ago


Simple pixelate function, just in case you are < 5.3



<?php

function pixelate(&$image, $pixelsize){

    $maxX = imagesx($image);

    $maxY = imagesy($image);

    $rad=floor($pixelsize/2);

    for($x=$rad;$x<$maxX;$x+=$pixelsize)

        for($y=$rad;$y<$maxY;$y+=$pixelsize){

            $color = imagecolorat($image, $x, $y);

            imagefilledrectangle ($image, $x-$rad, $y-$rad, $x+$pixelsize-1, $y+$pixelsize-1,$color);

        }

}

?>

down

cookie at backbone dot sk ¶

8 months ago


a function to create nice vignette effect:



<?php



function vignette($im){

    global $width, $height;    

    $width = imagesx($im);

    $height = imagesy($im);



    function effect($x, $y, &$rgb){

        global $width, $height;    

            

        $sharp = 0.4; // 0 - 10 small is sharpnes,  

        $level = 0.7; // 0 - 1 small is brighter



        $l = sin(M_PI / $width * $x) * sin(M_PI / $height * $y);

        $l = pow($l, $sharp);

        

        $l = 1 - $level * (1 - $l);

        

        $rgb['red'] *= $l;

        $rgb['green'] *= $l;

        $rgb['blue'] *= $l;

    }



    for($x = 0; $x < imagesx($im); ++$x){

        for($y = 0; $y < imagesy($im); ++$y){   

            $index = imagecolorat($im, $x, $y);

            $rgb = imagecolorsforindex($im, $index);

            effect($x, $y, $rgb);

            $color = imagecolorallocate($im, $rgb['red'], $rgb['green'], $rgb['blue']);



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

        }

    }

    return(true);

}



$im = imagecreatefromjpeg('cars7_134.jpg');



if($im and vignette($im)){

    header('Content-Type: image/jpeg');

    imagejpeg($im);

    imagedestroy($im);

}else{

    echo 'Vignette failed.';

}

?>

down

mail at pedrocandeias dot com ¶

1 year ago


// 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);



?>

down

hadrien dot jouet at grownseed dot net ¶

1 year ago


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]);

}

?>

down

mail at kavisiegel dot com ¶

3 years ago


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);

?>

down

ssttoo at gmail dot com ¶

5 years ago


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.

down

admin at phpgfx dot com ¶

5 years ago


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 );

    }

}



?>

down

webmaster at designsbykosi dot info ¶

6 years ago


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.

down

fananf at nerdshack dot com ¶

6 years ago


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.

down

trucex email over at gmail ¶

6 years ago


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.

down

nancy at hypertextdigital dot com ¶

6 years ago


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.

down

santibari at fibertel dot com ¶

7 years ago


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

?>

down

webmaster at qudi dot de ¶

7 years ago


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);

}

down

a php user at nowhere dot com ¶

7 years ago


http://www.hudzilla.org/phpbook/read.php/11_2_15

for more detailed info, and some <i>arg</i> guidelines.

down

vdepizzol at hotmail dot com ¶

8 years ago


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);

?>

down

kees at tweakers dot net ¶

8 years ago


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.

down

-1

Kae Cyphet ¶

5 years ago


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;

}

?>

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