imagecolortransparent
The comment below is an extremely good workaround
however, php did throw lots of warnings at me when i had error reporting set to E_ALL
this can be avoided with one line of code and no impact (as i can see) to the rest of the function
<?php
//include this file whenever you have to use imageconvolution...
//you can use in your project, but keep the comment below :)
//great for any image manipulation library
//Made by Chao Xu(Mgccl) 2/28/07
//www.webdevlogs.com
//V 1.0
if(!function_exists('imageconvolution')){
function imageconvolution($src, $filter, $filter_div, $offset){
if ($src==NULL) {
return 0;
}
$sx = imagesx($src);
$sy = imagesy($src);
$srcback = ImageCreateTrueColor ($sx, $sy);
ImageCopy($srcback, $src,0,0,0,0,$sx,$sy);
if($srcback==NULL){
return 0;
}
#FIX HERE
#$pxl array was the problem so simply set it with very low values
$pxl = array(1,1);
#this little fix worked for me as the undefined array threw out errors
for ($y=0; $y<$sy; ++$y){
for($x=0; $x<$sx; ++$x){
$new_r = $new_g = $new_b = 0;
$alpha = imagecolorat($srcback, $pxl[0], $pxl[1]);
$new_a = $alpha >> 24;
for ($j=0; $j<3; ++$j) {
$yv = min(max($y - 1 + $j, 0), $sy - 1);
for ($i=0; $i<3; ++$i) {
$pxl = array(min(max($x - 1 + $i, 0), $sx - 1), $yv);
$rgb = imagecolorat($srcback, $pxl[0], $pxl[1]);
$new_r += (($rgb >> 16) & 0xFF) * $filter[$j][$i];
$new_g += (($rgb >> 8) & 0xFF) * $filter[$j][$i];
$new_b += ($rgb & 0xFF) * $filter[$j][$i];
}
}
$new_r = ($new_r/$filter_div)+$offset;
$new_g = ($new_g/$filter_div)+$offset;
$new_b = ($new_b/$filter_div)+$offset;
$new_r = ($new_r > 255)? 255 : (($new_r < 0)? 0:$new_r);
$new_g = ($new_g > 255)? 255 : (($new_g < 0)? 0:$new_g);
$new_b = ($new_b > 255)? 255 : (($new_b < 0)? 0:$new_b);
$new_pxl = ImageColorAllocateAlpha($src, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
if ($new_pxl == -1) {
$new_pxl = ImageColorClosestAlpha($src, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
}
if (($y >= 0) && ($y < $sy)) {
imagesetpixel($src, $x, $y, $new_pxl);
}
}
}
imagedestroy($srcback);
return 1;
}
}
?>
imageconvolution
(PHP 5 >= 5.1.0)
imageconvolution — Applique une matrice de la convolution 3x3, en utilisant le coefficient et l'excentrage
Description
bool imageconvolution
( resource $image
, array $matrix
, float $div
, float $offset
)
Applique une matrice de la convolution 3x3, en utilisant le coefficient et l'excentrage.
Liste de paramètres
- image
-
Une ressource d'image, retourné par une des fonctions de création d'images, comme imagecreatetruecolor().
- matrix
-
Une matrice 3x3 : un tableau contenant trois tableaux de trois nombres à virgules flottantes.
- div
-
Le diviseur du résultat de la convolution, utilisé pour la normalisation.
- offset
-
Valeurs de retour
Cette fonction retourne TRUE en cas de succès, FALSE en cas d'échec.
Exemples
Exemple #1 Impression du logo PHP.net
<?php
$image = imagecreatefromgif('http://www.php.net/images/php.gif');
$emboss = array(array(2, 0, 0), array(0, -1, 0), array(0, 0, -1));
imageconvolution($image, $emboss, 1, 127);
header('Content-Type: image/png');
imagepng($image, null, 9);
?>
L'exemple ci-dessus va afficher :
Exemple #2 Floue gaussien
<?php
$image = imagecreatetruecolor(180,40);
// Écrit le texte et applique un floue gaussien sur l'image
imagestring($image, 5, 10, 8, 'Texte floue goussien', 0x00ff00);
$gaussian = array(array(1.0, 2.0, 1.0), array(2.0, 4.0, 2.0), array(1.0, 2.0, 1.0));
imageconvolution($image, $gaussian, 16, 0);
// Récrit le texte pour la comparaison
imagestring($image, 5, 10, 18, 'Texte floue goussien', 0x00ff00);
header('Content-Type: image/png');
imagepng($image, null, 9);
?>
L'exemple ci-dessus va afficher :
Notes
Note: Cette fonction n'est disponible que si PHP est compilé avec la version embarquée de la bibliothèque GD.
add a note
User Contributed Notesimageconvolution
Jase
14-Sep-2007 12:53
14-Sep-2007 12:53
mgcclx at gmail dot com
01-Mar-2007 04:55
01-Mar-2007 04:55
imageconvolution() does not appear in PHP with non-bundled GD libraries. It is a rare situation, but it still happens. That's why I wrote a replication of imageconvolution() in PHP. Compare to the post below, this one makes the use of offset and 30% faster.
Because it's written in PHP, it is 50 times slower than the bundled version.
Actually, this is a replication of gdimageconvolutaion() of GD library, it does not support data validating feature imageconvolution() have. But I guess people who uses this function knows their stuff.
THE SCRIPT:
<?php
//include this file whenever you have to use imageconvolution...
//you can use in your project, but keep the comment below :)
//great for any image manipulation library
//Made by Chao Xu(Mgccl) 2/28/07
//www.webdevlogs.com
//V 1.0
if(!function_exists('imageconvolution')){
function imageconvolution($src, $filter, $filter_div, $offset){
if ($src==NULL) {
return 0;
}
$sx = imagesx($src);
$sy = imagesy($src);
$srcback = ImageCreateTrueColor ($sx, $sy);
ImageCopy($srcback, $src,0,0,0,0,$sx,$sy);
if($srcback==NULL){
return 0;
}
for ($y=0; $y<$sy; ++$y){
for($x=0; $x<$sx; ++$x){
$new_r = $new_g = $new_b = 0;
$alpha = imagecolorat($srcback, $pxl[0], $pxl[1]);
$new_a = $alpha >> 24;
for ($j=0; $j<3; ++$j) {
$yv = min(max($y - 1 + $j, 0), $sy - 1);
for ($i=0; $i<3; ++$i) {
$pxl = array(min(max($x - 1 + $i, 0), $sx - 1), $yv);
$rgb = imagecolorat($srcback, $pxl[0], $pxl[1]);
$new_r += (($rgb >> 16) & 0xFF) * $filter[$j][$i];
$new_g += (($rgb >> 8) & 0xFF) * $filter[$j][$i];
$new_b += ($rgb & 0xFF) * $filter[$j][$i];
}
}
$new_r = ($new_r/$filter_div)+$offset;
$new_g = ($new_g/$filter_div)+$offset;
$new_b = ($new_b/$filter_div)+$offset;
$new_r = ($new_r > 255)? 255 : (($new_r < 0)? 0:$new_r);
$new_g = ($new_g > 255)? 255 : (($new_g < 0)? 0:$new_g);
$new_b = ($new_b > 255)? 255 : (($new_b < 0)? 0:$new_b);
$new_pxl = ImageColorAllocateAlpha($src, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
if ($new_pxl == -1) {
$new_pxl = ImageColorClosestAlpha($src, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
}
if (($y >= 0) && ($y < $sy)) {
imagesetpixel($src, $x, $y, $new_pxl);
}
}
}
imagedestroy($srcback);
return 1;
}
}
?>
interghost at crovortex dot com
31-Mar-2006 09:26
31-Mar-2006 09:26
an implementation of this function for PHP versions <5.1
<?php
if(!function_exists("imageconvolution"))
{
function imageconvolution(&$img,$mat,$div,$off)
{
if(!imageistruecolor($img) || !is_array($mat) || count($mat)!=3 || count($mat[0])!=3 || count($mat[1])!=3 || count($mat[2])!=3) return FALSE;
unset($bojainfo);
for($nx=0;$nx<imagesx($img)-1;$nx++)
{
for($ny=0;$ny<imagesy($img)-1;$ny++)
{
$rgb=imagecolorat($img,$nx,$ny);
$bojainfo[$nx][$ny][r]=($rgb>>16)&0xFF;
$bojainfo[$nx][$ny][g]=($rgb>>8)&0xFF;
$bojainfo[$nx][$ny][b]=$rgb&0xFF;
}
}
for($nx=1;$nx<imagesx($img)-1;$nx++)
{
for($ny=1;$ny<imagesy($img)-1;$ny++)
{
$nr=$mat[0][0]*$bojainfo[$nx-1][$ny-1][r] + $mat[0][1]*$bojainfo[$nx][$ny-1][r] + $mat[0][2]*$bojainfo[$nx+1][$ny-1][r] + $mat[1][0]*$bojainfo[$nx-1][$ny][r] + $mat[1][1]*$bojainfo[$nx][$ny][r] + $mat[1][2]*$bojainfo[$nx+1][$ny][r] + $mat[2][0]*$bojainfo[$nx-1][$ny+1][r] + $mat[2][1]*$bojainfo[$nx][$ny+1][r] + $mat[2][2]*$bojainfo[$nx+1][$ny+1][r];
$nr=intval(round($nr/$div));
if($nr<0) $nr=0;
elseif($nr>255) $nr=255;
$ng=$mat[0][0]*$bojainfo[$nx-1][$ny-1][g] + $mat[0][1]*$bojainfo[$nx][$ny-1][g] + $mat[0][2]*$bojainfo[$nx+1][$ny-1][g] + $mat[1][0]*$bojainfo[$nx-1][$ny][g] + $mat[1][1]*$bojainfo[$nx][$ny][g] + $mat[1][2]*$bojainfo[$nx+1][$ny][g] + $mat[2][0]*$bojainfo[$nx-1][$ny+1][g] + $mat[2][1]*$bojainfo[$nx][$ny+1][g] + $mat[2][2]*$bojainfo[$nx+1][$ny+1][g];
$ng=intval(round($ng/$div));
if($ng<0) $ng=0;
elseif($ng>255) $ng=255;
$nb=$mat[0][0]*$bojainfo[$nx-1][$ny-1][b] + $mat[0][1]*$bojainfo[$nx][$ny-1][b] + $mat[0][2]*$bojainfo[$nx+1][$ny-1][b] + $mat[1][0]*$bojainfo[$nx-1][$ny][b] + $mat[1][1]*$bojainfo[$nx][$ny][b] + $mat[1][2]*$bojainfo[$nx+1][$ny][b] + $mat[2][0]*$bojainfo[$nx-1][$ny+1][b] + $mat[2][1]*$bojainfo[$nx][$ny+1][b] + $mat[2][2]*$bojainfo[$nx+1][$ny+1][b];
$nb=intval(round($nb/$div));
if($nb<0) $nb=0;
elseif($nb>255) $nb=255;
$nrgb=($nr<<16)+($ng<<8)+$nb;
if(!imagesetpixel($img,$nx,$ny,$nrgb)) return FALSE;
}
}
return TRUE;
}
}
?>
it's a bit slowish so I wouldn't recommend big images, also offset is not implemented (don't know what it's suppose to do)
mlconnor at yahoo dot com
21-Mar-2006 06:00
21-Mar-2006 06:00
I've seen many people come up with ways to do a drop shadow behind a rectangle such as a picture. I haven't found one yet that was fast, PHP 4 complaint, and nice looking. Here is one I came up with last night. It takes an image, fills it with the background, and creates a blurred drop shadow at the specified coords using the colors and the distance offset specified. It looks great!!!
function blurRect(&$image, $distance, $rectX1, $rectY1, $rectX2, $rectY2, $shadowR, $shadowG, $shadowB, $backR, $backG, $backB) {
$potentialOverlap = ($distance * 2) * ($distance * 2);
$backgroundColor = imagecolorallocate($image, $backR, $backG, $backB);
$shadowColor = imagecolorallocate($image, $shadowR, $shadowG, $shadowB);
$imageWidth = imagesx($image);
$imageHeight = imagesy($image);
imageFilledRectangle($image, 0, 0, $imageWidth - 1, $imageHeight - 1, $backgroundColor);
imageFilledRectangle($image, $rectX1, $rectY1, $rectX2, $rectY2, $shadowColor);
for ( $pointX = $rectX1 - $distance; $pointX < $imageWidth; $pointX++ ) {
for ( $pointY = $rectY1 - $distance; $pointY < $imageHeight; $pointY++ ) {
if ( $pointX > $rectX1 + $distance &&
$pointX < $rectX2 - $distance &&
$pointY > $rectY1 + $distance &&
$pointY < $rectY2 - $distance ) {
$pointY = $rectY2 - $distance;
}
$boxX1 = $pointX - $distance;
$boxY1 = $pointY - $distance;
$boxX2 = $pointX + $distance;
$boxY2 = $pointY + $distance;
$xOverlap = max(0, min($boxX2, $rectX2) - max($boxX1, $rectX1));
$yOverlap = max(0, min($boxY2, $rectY2) - max($boxY1, $rectY1));
$totalOverlap = $xOverlap * $yOverlap;
$shadowPcnt = $totalOverlap / $potentialOverlap;
$backPcnt = 1.0 - $shadowPcnt;
$newR = $shadowR * $shadowPcnt + $backR * $backPcnt;
$newG = $shadowG * $shadowPcnt + $backG * $backPcnt;
$newB = $shadowB * $shadowPcnt + $backB * $backPcnt;
$newcol = imagecolorallocate($image, $newR, $newG, $newB);
imagesetpixel($image, $pointX, $pointY, $newcol);
}
}
}
jonathan dot aquino at gmail dot com
18-Jan-2006 06:30
18-Jan-2006 06:30
For those who don't have PHP 5.1 and thus don't have imageconvolution, I found some code to do blurring: http://www.hudzilla.org/php/11_2_25.php Works quite nicely.
dyer85 at gmail dot com
07-Jan-2006 11:24
07-Jan-2006 11:24
Took me a while, but thanks to a couple of the user notes on the array_values PHP documentation page, I was able to come up with a way to dynamically compute the divisor.
I'm using PHP 5.1.0b2 on Win32 with the bundled GD library. When I try and use the imageconvolution function, whether normally, or via the functions below, the resulting image (I've only tried JPEGs and GIFs), always comes out far too bright, even when the divisor makes matrix sum equal to 1. The only thing that would reduce the brightness was to make the offset argument ridiculously large. So, I'm not sure if this effects anyone else.
Here are the functions with an example:
<?php
$im = imagecreatefromjpeg('path/to/pic.jpg');
$matrix = array( array(5,5,5),
array(5,15,5),
array(5,5,5) );
makeFilter($im, $matrix);
header ( 'Content-Type: image/jpeg' );
imagejpeg($im);
imagedestroy($im);
/**
* functions
*/
// This flattens the 3X3 array matrix, so we can get the sum of all the values
function array_flatten($array) {
(array)$tempArray = array();
foreach ( $array as $value ) {
if ( is_array($value) ) {
$tempArray = array_merge($tempArray, array_flatten($value));
} else {
$tempArray[] = $value;
}
}
return $tempArray;
}
// Creates the divisor value dynamically, and passes offset
function makeFilter($resource, $matrix, $offset=1.0) {
global $$resource;
(float)$divisor = array_sum(array_flatten($matrix));
return imageconvolution($resource, $matrix, $divisor, $offset) ? true : false;
}
?>
27-Oct-2005 02:32
The example below didn't provide a 3x3 matrix. Correctly, it's a multidimensional array.
<?php
$matrix = array( array( -1, -1, -1 ),
array( -1, 16, -1 ),
array( -1, -1, -1 ) );
?>
timeshifting at gmail dot com
25-Aug-2005 12:40
25-Aug-2005 12:40
Matrices can be used for sharpening, blurring, edge detection, etc, ala Photoshop.
A sharpening example:
<?php
$sharpenMatrix = array(-1,-1,-1,-1,16,-1,-1,-1,-1);
$divisor = 8;
$offset = 0;
imageconvolution($myImage, $sharpenMatrix, $divisor, $offset);
?>
Below is some information on building different kinds of matrices. (If you have photoshop (or PSP, GIMP) you can test out your matrices before applying them in PHP)
http://loriweb.pair.com/8udf-basics.html (covers blurs)
http://loriweb.pair.com/8udf-sharpen.html
http://loriweb.pair.com/8udf-edges.html
http://loriweb.pair.com/8udf-emboss.html