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Digg  imagefilter
Applies a filter to an image
(PHP 5)
Example 1011. imagefilter() grayscale example<?phpExample 1012. imagefilter() brightness example<?phpExample 1013. imagefilter() colorize example<?phpCode Examples / Notes » imagefilterwebmaster
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.
nancy
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. admin
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, $blue ); } } ?> panuworld
The documentation misses the exact meaning and valid ranges of the arguments for ImageFilter(). According to the 5.2.0 sources the arguments are: IMG_FILTER_BRIGHTNESS -255 = min brightness, 0 = no change, +255 = max brightness IMG_FILTER_CONTRAST -100 = max contrast, 0 = no change, +100 = min contrast (note the direction!) IMG_FILTER_COLORIZE Adds (subtracts) specified RGB values to each pixel. The valid range for each color is -255...+255, not 0...255. The correct order is red, green, blue. -255 = min, 0 = no change, +255 = max This has not much to do with IMG_FILTER_GRAYSCALE. IMG_FILTER_SMOOTH Applies a 9-cell convolution matrix where center pixel has the weight arg1 and others weight of 1.0. The result is normalized by dividing the sum with arg1 + 8.0 (sum of the matrix). any float is accepted, large value (in practice: 2048 or more) = no change ImageFilter seem to return false if the argument(s) are out of range for the chosen filter. trucex email over
It appears that imagefilter doesn't play nice with apha. If you run an imagefilter on a transparent image it'll return a black image...similar to a lot of Photoshop plugins do.
fananf
If you're looking for fast sepia effect that can be used for on-the-fly thumbnails generation you can't use sophisticated functions. The faster and much better way than described by webmaster at qudi dot de in the note from 31-Jan-2006 is applying colorize filter AFTER grayscale. <?php (...) imagefilter($yourimage, IMG_FILTER_GRAYSCALE); imagefilter($yourimage, IMG_FILTER_COLORIZE, 90, 60, 40); (...) ?> I used (90,60,40) for my sepia after couple of tests, however, if you need darker or lighter just check what suits you best. kees
From what i have been able to find from this function, it accepts the following arguments: IMG_FILTER_NEGATE IMG_FILTER_GRAYSCALE IMG_FILTER_EDGEDETECT IMG_FILTER_GAUSSIAN_BLUR IMG_FILTER_SELECTIVE_BLUR IMG_FILTER_EMBOSS IMG_FILTER_MEAN_REMOVAL The following arguments need one or more arguments. IMG_FILTER_SMOOTH, -1924.124 IMG_FILTER_COLORIZE, -127.12, -127.98, 127 IMG_FILTER_CONTRAST, -90 IMG_FILTER_BRIGHTNESS, 98 I haven't tested them all, the names speak for themselves. webmaster
for a quick, ok-looking, sepia-effect (also in php4) I just use this little fellow, since a real implementation of sepia was just way too slow. function pseudosepia(&$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); } vdepizzol
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($im); ?> santibari
A colorize algorithm wich preserves color luminosity (i.e black will output black, and white will output white). This works in PHP4 and is great for customizing interfaces dinamically. <?php function colorize($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 ?> a php user
http://www.hudzilla.org/phpbook/read.php/11_2_15 for more detailed info, and some <i>arg</i> guidelines. |
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