PHP: imageantialias

imageantialias

php at 3d-box dot com
08-Jul-2006 09:55


This might help some people but I have created an antialiased, filled, ellipse function - the source for which is here:-



http://personal.3d-box.com/php/filledellipseaa.php



As the code is too much to put here!

jb at flamedesign dot dk
30-Mar-2006 02:37


Official GD Lib manual link:



http://www.boutell.com/gd/manual2.0.33.html#gdImageSetAntiAliased

n-dream at gmx dot ch
18-Feb-2006 10:18


The following function draws an AntiAliased (unfilled) Ellipse.

It is used just liked the nomral ImageEllipse function.

The optional parameter sets the number of segments...



function ImageEllipseAA( &$img, $x, $y, $w, $h,$color,$segments=70) 

{

    $w=$w/2;

    $h=$h/2;

    $jump=2*M_PI/$segments;

    $oldx=$x+sin(-$jump)*$w;

    $oldy=$y+cos(-$jump)*$h;

    for($i=0;$i<2*(M_PI);$i+=$jump)

    {

        $newx=$x+sin($i)*$w;

        $newy=$y+cos($i)*$h;

        ImageLine($img,$newx,$newy,$oldx,$oldy,$color);

        $oldx=$newx;

        $oldy=$newy;

    }

}

klaas at kosmokrator dot com
15-Feb-2006 05:22


Here is an optimized version of the optimized version of the antialiased circle function by sebbi: (more than 20 times faster)...



<?php



    function imageSmoothCircle( &$img, $cx, $cy, $cr, $color ) {

        $ir = $cr;

        $ix = 0;

        $iy = $ir;

        $ig = 2 * $ir - 3;

        $idgr = -6;

        $idgd = 4 * $ir - 10;

        $fill = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], 0 );

        imageLine( $img, $cx + $cr - 1, $cy, $cx, $cy, $fill );

        imageLine( $img, $cx - $cr + 1, $cy, $cx - 1, $cy, $fill );

        imageLine( $img, $cx, $cy + $cr - 1, $cx, $cy + 1, $fill );

        imageLine( $img, $cx, $cy - $cr + 1, $cx, $cy - 1, $fill );

        $draw = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], 42 );

        imageSetPixel( $img, $cx + $cr, $cy, $draw );

        imageSetPixel( $img, $cx - $cr, $cy, $draw );

        imageSetPixel( $img, $cx, $cy + $cr, $draw );

        imageSetPixel( $img, $cx, $cy - $cr, $draw );

        while ( $ix <= $iy - 2 ) {

            if ( $ig < 0 ) {

                $ig += $idgd;

                $idgd -= 8;

                $iy--;

            } else {

                $ig += $idgr;

                $idgd -= 4;

            }

            $idgr -= 4;

            $ix++;

            imageLine( $img, $cx + $ix, $cy + $iy - 1, $cx + $ix, $cy + $ix, $fill );

            imageLine( $img, $cx + $ix, $cy - $iy + 1, $cx + $ix, $cy - $ix, $fill );

            imageLine( $img, $cx - $ix, $cy + $iy - 1, $cx - $ix, $cy + $ix, $fill );

            imageLine( $img, $cx - $ix, $cy - $iy + 1, $cx - $ix, $cy - $ix, $fill );

            imageLine( $img, $cx + $iy - 1, $cy + $ix, $cx + $ix, $cy + $ix, $fill );

            imageLine( $img, $cx + $iy - 1, $cy - $ix, $cx + $ix, $cy - $ix, $fill );

            imageLine( $img, $cx - $iy + 1, $cy + $ix, $cx - $ix, $cy + $ix, $fill );

            imageLine( $img, $cx - $iy + 1, $cy - $ix, $cx - $ix, $cy - $ix, $fill );

            $filled = 0;

            for ( $xx = $ix - 0.45; $xx < $ix + 0.5; $xx += 0.2 ) {

                for ( $yy = $iy - 0.45; $yy < $iy + 0.5; $yy += 0.2 ) {

                    if ( sqrt( pow( $xx, 2 ) + pow( $yy, 2 ) ) < $cr ) $filled += 4;

                }

            }

            $draw = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], ( 100 - $filled ) );

            imageSetPixel( $img, $cx + $ix, $cy + $iy, $draw );

            imageSetPixel( $img, $cx + $ix, $cy - $iy, $draw );

            imageSetPixel( $img, $cx - $ix, $cy + $iy, $draw );

            imageSetPixel( $img, $cx - $ix, $cy - $iy, $draw );

            imageSetPixel( $img, $cx + $iy, $cy + $ix, $draw );

            imageSetPixel( $img, $cx + $iy, $cy - $ix, $draw );

            imageSetPixel( $img, $cx - $iy, $cy + $ix, $draw );

            imageSetPixel( $img, $cx - $iy, $cy - $ix, $draw );

        }

    }



    $img = imageCreateTrueColor( 320, 240 );



    imageSmoothCircle( $img, 160, 120, 100, array( 'R' => 0xCC, 'G' => 0x33, 'B' => 0x00 ) );

    imageSmoothCircle( $img, 170, 110,  75, array( 'R' => 0xDD, 'G' => 0x66, 'B' => 0x00 ) );

    imageSmoothCircle( $img, 180, 100,  50, array( 'R' => 0xEE, 'G' => 0x99, 'B' => 0x00 ) );

    imageSmoothCircle( $img, 190,  90,  25, array( 'R' => 0xFF, 'G' => 0xCC, 'B' => 0x00 ) );



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

    imagePNG( $img );



?>

voinic at NOSgmailPAM dot com
12-Jan-2006 02:22


The only trick I found to draw an antialiased polygon AND keep it transparent (to use them as overlays in google maps for example)... make two images and merge them. Order of operations is important and the transparency color of the final image must be set after the merge:



<?

header("Content-type: image/png");



$values = array(

           40,  50,  // Point 1 (x, y)

           20,  240, // Point 2 (x, y)

           60,  60,  // Point 3 (x, y)

           240, 20,  // Point 4 (x, y)

           50,  40,  // Point 5 (x, y)

           10,  10  // Point 6 (x, y)

           );                    



$im = imagecreate(250, 250);

$bg = imagecolorallocate($im, 255, 255, 255);



$im2 = imagecreatetruecolor(250, 250);

$bg2 = imagecolorallocate($im2, 255, 255, 255);

imagefilledrectangle($im2,0,0,249,249,$bg2);

imagecolortransparent($im2, $bg);

imageantialias($im2, true);

$c_red = imagecolorallocate($im2, 255, 0, 0);

imagepolygon($im2, $values, 6, $c_red);

imageantialias($im2, false);



imagecopymerge($im, $im2,0,0,0,0,250,250,50);



imagecolortransparent($im, $bg);

$c_red_alpha = imagecolorallocatealpha($im, 255, 0, 0, 60);

imagefilledpolygon($im, $values, 6, $c_red_alpha);



imagepng($im);

imagedestroy($im);

imagedestroy($im2);

?>

sebbi at conceptT dot com
26-Sep-2005 07:06


I did a search in google and got following url:

http://www.isocalc.com/tutorials/antialias.htm

With this tutorial I was able to write a function to convert this algorithm into php, the result for a filled circel is this:

<?php

function imagefilledcircleantialiased(&$im, $cx, $cy, $r, $fgcolor, $bgcolor) {

  $fgcolors = imagecolorsforindex($im,$fgcolor);

  $bgcolors = imagecolorsforindex($im,$bgcolor);

  for ( $x = $cx - $r; $x <= $cx + $r; $x++ ) {

    for ( $y = $cy - $r; $y <= $cy + $r; $y++ ) {

      $rx = $x - $cx; $ry = $y - $cy;

      $ir = sqrt(( $rx == 0 ? 0 : pow($rx - 0.5*abs($rx)/$rx, 2) ) + ( $ry == 0 ? 0 : pow($ry - 0.5*abs($ry)/$ry, 2) ));

      $or = sqrt(( $rx == 0 ? 0 : pow($rx + 0.5*abs($rx)/$rx, 2) ) + ( $ry == 0 ? 0 : pow($ry + 0.5*abs($ry)/$ry, 2) ));

      if ( $or <= $r ) {

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

      }

      elseif ( $ir < $r ) {

        $filled = 0;

        for ( $xx = $x - 0.45; $xx < $x + 0.5; $xx+=0.1 ) {

          for ( $yy = $y - 0.45; $yy < $y + 0.5; $yy+=0.1 ) {

            $rxx = $xx - $cx; $ryy = $yy - $cy;

            if ( sqrt(pow($rxx, 2) + pow($ryy, 2)) < $r ) $filled++;

          }

        }

        $red = round($bgcolors['red'] + ( $fgcolors['red'] - $bgcolors['red'] ) * $filled / 100);

        $green = round($bgcolors['green'] + ( $fgcolors['green'] - $bgcolors['green'] ) * $filled / 100);

        $blue = round($bgcolors['blue'] + ( $fgcolors['blue'] - $bgcolors['blue'] ) * $filled / 100);

        imagesetpixel($im, $x, $y, imagecolorclosest($im, $red, $green, $blue));

      }

    }

  }

}



$width = 160;

$height = 200;

$r = 20;

$bgc = "651713";

$fgc = "b12b2c";



$im = imagecreate($width, $height);

$bgcolor = imagecolorallocate($im, hexdec(substr($bgc, 0, 2)), hexdec(substr($bgc, 2, 2)), hexdec(substr($bgc, 4, 2)));

for( $i = 0; $i < 100; $i++ ) {

    imagecolorallocate($im, ( hexdec(substr($fgc, 0, 2)) + $i*hexdec(substr($bgc, 0, 2))) / ($i + 1), ( hexdec(substr($fgc, 2, 2)) + $i*hexdec(substr($bgc, 2, 2))) / ($i + 1), ( hexdec(substr($fgc, 4, 2)) + $i*hexdec(substr($bgc, 4, 2))) / ($i + 1));

}

$fgcolor = imagecolorclosest($im, hexdec(substr($fgc, 0, 2)), hexdec(substr($fgc, 2, 2)), hexdec(substr($fgc, 4, 2)));



imagefilledcircleantialiased($im, 80, 100, $r, $fgcolor, $bgcolor);



header("Content-Type: image/png");

imagepng($im);

?>

An improvement would be to draw the inner rectangle or more rectangles in the circle with the builtin rectangle function to reduce the usage of imagesetpixel() from (2*r)^2 to 2*Pi*(r + epsilon), in other words, the dependency on r would break down from square to linear.

Another improvement would be to determine filled and unfilled triangles in the observed pixel and calculate their areas, so we can get rid of the inner loops for getting the fraction filled/unfilled.

One can easily modify this function to solve other problems like lines, unfilled circles, etc.

trimbo
06-Sep-2005 12:25


So far using PHP 5.0.4 I've managed to get Imageantialias() to work well with:

ImageLine()

ImagePolygon()



but not with:

ImageArc()

ImageEllipse()

ImageFilled*()



You can still draw antialiased filled polygons by drawing a hollow polygon on top of a filled one with the same dimensions:

<?php

        $points=array($x,$y, $x2,$y2, $x3,$y3);

        imageFilledPolygon($im, $points, 3, $gray );

        imagePolygon($im, $points, 3, $gray );

?>

klaas at kosmokrator dot com
24-May-2004 07:21


I have optimized the "imageSmoothLine" function by logang.



sample and download at:



http://www.kosmokrator.com/download/php/

logang at deltatee dot com
05-Aug-2003 03:28


I've writen some antialiasing functions for people who don't have the requirements for the builtin antialiasing. 



You can download a copy at: http://grey.deltatee.com/image.phps

Igor Garcia
30-Jun-2003 02:57


This function its only available if you have the BUNDLED version of GD. 

(PHP 4.3.2)

imageantialias

Description