Knowledge Base

Image Effects in PHP

1) Black and White effect using PHP

Below is the code for converting a image to black and white

$img = imagecreatefrompng(‘images.png’);
imagefilter($img,IMG_FILTER_GRAYSCALE);
imagepng($img,’bw.png’);
imagedestroy($img);
?>

Here images.png is original image and bw.png is the converted black and white image.
In the first line of code use imagecreatefromgif() if you are converting a gif image ,use imagecreatefromjpeg() if you are converting a jpeg image, user imagecreatefrombmp() if you are converting a bmp image

Similarly in line 3 use imagegif() for creating black and white gif image, use imagejpeg() for jpeg image,imagebmp for bmp image.

2) Negative effect on an image using PHP
Below is the code for converting a image to Negative

$img = imagecreatefrompng(‘images.png’);
imagefilter($img,IMG_FILTER_NEGATE);
imagepng($img,’negative.png’);
imagedestroy($img);
?>

Here images.png is original image and negative.png is the converted negative image.

In the first line of code use imagecreatefromgif() if you are converting a gif image ,use imagecreatefromjpeg() if you are converting a jpeg image, user imagecreatefrombmp() if you are converting a bmp image

Similarly in line 3 use imagegif() for creating negative in gif format, use imagejpeg() for jpeg format,imagebmp for bmp format.

3) Sepia effect on an image using PHP
Below is the code for converting a image using Sepia Effect

$img = imagecreatefrompng(‘images.png’);
imagefilter($img,IMG_FILTER_GRAYSCALE);
imagefilter($img,IMG_FILTER_COLORIZE,100,50,0);
imagepng($img,’sepia.png’);
imagedestroy($img);
?>

Here images.png is original image and sepia.png is the converted sepia image.

In the first line of code use imagecreatefromgif() if you are converting a gif image ,use imagecreatefromjpeg() if you are converting a jpeg image, user imagecreatefrombmp() if you are converting a bmp image

Similarly in line 3 use imagegif() for creating sepia in gif format, use imagejpeg() for jpeg format,imagebmp for bmp format.

4) Hue effect on image using PHP Script
You will need to include the below given 3 functions for applying hue effect on your image

function rgb2hsl($r, $g, $b) {
$var_R = ($r / 255);
$var_G = ($g / 255);
$var_B = ($b / 255);

$var_Min = min($var_R, $var_G, $var_B);
$var_Max = max($var_R, $var_G, $var_B);
$del_Max = $var_Max – $var_Min;

$v = $var_Max;

if ($del_Max == 0) {
$h = 0;
$s = 0;
} else {
$s = $del_Max / $var_Max;

$del_R = ( ( ( $var_Max – $var_R ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
$del_G = ( ( ( $var_Max – $var_G ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
$del_B = ( ( ( $var_Max – $var_B ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;

if($var_R == $var_Max) $h = $del_B – $del_G;
else if ($var_G == $var_Max) $h = ( 1 / 3 ) + $del_R – $del_B;
else if ($var_B == $var_Max) $h = ( 2 / 3 ) + $del_G – $del_R;
if ($h < 0) $h++; if ($h > 1) $h–;
}
return array($h, $s, $v);
}

function hsl2rgb($h, $s, $v) {
if($s == 0) {
$r = $g = $B = $v * 255;
} else {
$var_H = $h * 6;
$var_i = floor( $var_H );
$var_1 = $v * ( 1 – $s );
$var_2 = $v * ( 1 – $s * ( $var_H – $var_i ) );
$var_3 = $v * ( 1 – $s * (1 – ( $var_H – $var_i ) ) );

if ($var_i == 0) { $var_R = $v ; $var_G = $var_3 ; $var_B = $var_1 ; }
else if ($var_i == 1) { $var_R = $var_2 ; $var_G = $v ; $var_B = $var_1 ; }
else if ($var_i == 2) { $var_R = $var_1 ; $var_G = $v ; $var_B = $var_3 ; }
else if ($var_i == 3) { $var_R = $var_1 ; $var_G = $var_2 ; $var_B = $v ; }
else if ($var_i == 4) { $var_R = $var_3 ; $var_G = $var_1 ; $var_B = $v ; }
else { $var_R = $v ; $var_G = $var_1 ; $var_B = $var_2 ; }

$r = $var_R * 255;
$g = $var_G * 255;
$B = $var_B * 255;
}
return array($r, $g, $B);
}

function imagehue(&$image, $angle) {
if($angle % 360 == 0) return;
$width = imagesx($image);
$height = imagesy($image);

for($x = 0; $x < $width; $x++) { for($y = 0; $y < $height; $y++) { $rgb = imagecolorat($image, $x, $y); $r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;
$alpha = ($rgb & 0x7F000000) >> 24;
list($h, $s, $l) = rgb2hsl($r, $g, $b);
$h += $angle / 360;
if($h > 1) $h–;
list($r, $g, $b) = hsl2rgb($h, $s, $l);
imagesetpixel($image, $x, $y, imagecolorallocatealpha($image, $r, $g, $b, $alpha));
}
}
}

After including the above functions you just need to call imagehue() function like shown below.