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php-gdBetter antialias with GD


This is rather a hack, than systematic solution, so mind using other libs like Imagemagick for PHP to get native antialiasing support.

<?php

$im = imagecreatetruecolor(4000, 3000);
imageantialias($im, true);

$c_black = imageColorAllocate($im, 0,0,0);
$c_green = imageColorAllocate($im, 46,204,64);

imagefilledellipse($im, 2000, 1500, 800, 800, $c_green);

$imf = imagecreatetruecolor(400, 300);
imagecopyresampled($imf, $im, 0,0,0,0, 400,300,4000,3000);

imagePng($imf, '/tmp/image.png');ctrl + c
imagecreatetruecolor

creates true color GD image object with specified width & height

imageantialias

enable antialiasing for the given image

imageColorAllocate

creates color object to later use in image

imagefilledellipse

creates ellipse with specified coordinates, radius and color

4000, 3000

we have created initial image of large size (10x what we need in result)

imagecopyresampled

now we resize source large image (4000x3000) to resulting image (400x300) to apply better antialiasing

imagePng

saves image in PNG format to the given path


Better antialias with GD, php gd

Usage example

<?php

$im = imagecreatetruecolor(4000, 3000);
imageantialias($im, true);

$c_black = imageColorAllocate($im, 0,0,0);
$c_green = imageColorAllocate($im, 46,204,64);

imagefilledellipse($im, 2000, 1500, 800, 800, $c_green);

$imf = imagecreatetruecolor(400, 300);
imagecopyresampled($imf, $im, 0,0,0,0, 400,300,4000,3000);

imagePng($imf, '/tmp/image.png');