Last updated: Fri, 18 May 2012

imagefilter

(PHP 5)

imagefilter — Applies a filter to an image

Beschreibung

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

imagefilter() applies the given filter filtertype on the image.

Parameter-Liste

image

Eine von den verschiedenen Erzeugungsfunktionen wie imagecreatetruecolor() gelieferte Grafikressource.

filtertype

filtertype can be one of the following:

IMG_FILTER_NEGATE: Reverses all colors of the image.
IMG_FILTER_GRAYSCALE: Converts the image into grayscale.
IMG_FILTER_BRIGHTNESS: Changes the brightness of the image. Use arg1 to set the level of brightness.
IMG_FILTER_CONTRAST: Changes the contrast of the image. Use arg1 to set the level of contrast.
IMG_FILTER_COLORIZE: Like IMG_FILTER_GRAYSCALE, except you can specify the color. Use arg1, arg2 and arg3 in the form of red, blue, green and arg4 for the alpha channel. The range for each color is 0 to 255.
IMG_FILTER_EDGEDETECT: Uses edge detection to highlight the edges in the image.
IMG_FILTER_EMBOSS: Embosses the image.
IMG_FILTER_GAUSSIAN_BLUR: Blurs the image using the Gaussian method.
IMG_FILTER_SELECTIVE_BLUR: Blurs the image.
IMG_FILTER_MEAN_REMOVAL: Uses mean removal to achieve a "sketchy" effect.
IMG_FILTER_SMOOTH: Makes the image smoother. Use arg1 to set the level of smoothness.
IMG_FILTER_PIXELATE: Applies pixelation effect to the image, use arg1 to set the block size and arg2 to set the pixelation effect mode.

arg1

IMG_FILTER_BRIGHTNESS: Brightness level.
IMG_FILTER_CONTRAST: Contrast level.
IMG_FILTER_COLORIZE: Wert der Rotkomponente.
IMG_FILTER_SMOOTH: Smoothness level.
IMG_FILTER_PIXELATE: Block size in pixels.

arg2

IMG_FILTER_COLORIZE: Wert der Grünkomponente.
IMG_FILTER_PIXELATE: Whether to use advanced pixelation effect or not (defaults to FALSE).

arg3

IMG_FILTER_COLORIZE: Wert der Blaukomponente.

arg4

IMG_FILTER_COLORIZE: Alpha channel, A value between 0 and 127. 0 indicates completely opaque while 127 indicates completely transparent.

Rückgabewerte

Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.

Changelog

Version	Beschreibung
5.3.0	Pixelation support (`IMG_FILTER_PIXELATE`) was added.
5.2.5	Alpha support for `IMG_FILTER_COLORIZE` was added.

Beispiele

Beispiel #1 imagefilter() grayscale example


<?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);
?>

Beispiel #2 imagefilter() brightness example


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

if($im && imagefilter($im, IMG_FILTER_BRIGHTNESS, 20))
{
    echo 'Image brightness changed.';

    imagepng($im, 'sean.png');
    imagedestroy($im);
}
else
{
    echo 'Image brightness change failed.';
}
?>

Beispiel #3 imagefilter() colorize example


<?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($im, 'philip.png');
    imagedestroy($im);
}
else
{
    echo 'Green shading failed.';
}
?>

Beispiel #4 imagefilter() negate example


<?php
// Define our negate function so its portable for 
// php versions without 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 successfully converted to negative colors.';

    imagejpeg($im, 'kalle.jpg', 100);
    imagedestroy($im);
}
else
{
    echo 'Converting to negative colors failed.';
}
?>

Beispiel #5 imagefilter() pixelate example


<?php
// Load the PHP logo, we need to create two instances 
// to show the differences
$logo1 = imagecreatefrompng('./php.png');
$logo2 = imagecreatefrompng('./php.png');

// Create the image instance we want to show the 
// differences on
$output = imagecreatetruecolor(imagesx($logo1) * 2, imagesy($logo1));

// Apply pixelation to each instance, with a block 
// size of 3
imagefilter($logo1, IMG_FILTER_PIXELATE, 3);
imagefilter($logo2, IMG_FILTER_PIXELATE, 3, true);

// Merge the differences onto the output image
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);

// Output the differences
header('Content-Type: image/png');
imagepng($output);
imagedestroy($output);
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

Anmerkungen

Hinweis: Diese Funktion steht nur zur Verfügung, wenn PHP mit der GD Bibliothek übersetzt wurde, die mit PHP zusammen erhältlich ist.

Siehe auch

imageconvolution() - Apply a 3x3 convolution matrix, using coefficient and offset

add a note User Contributed Notes
imagefilter

webmaster at designsbykosi dot info
08-May-2007 09:56


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 06:26


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 09:31


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 03:55


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 11:16


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 08:37


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 03:53


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 09:48


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 10:36


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
21-Jul-2004 03:26


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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Last updated: Fri, 18 May 2012