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When processing images in PHP, GD libraries are commonly used to perform various image operations. The imageantialias() function is a tool provided by the GD library to enable anti-aliasing effect. Anti-aliasing can smooth out the lines and shape edges in the image, avoiding jagged visual effects, thereby improving image quality. So, will the size of the image change after imageantialias() is enabled?
The imageantialias() function is defined as follows:
bool imageantialias ( resource $image , bool $enabled )
$image is the image resource handle
Anti-aliasing is enabled when $enabled is true , and closed when false
This function is only effective for drawing functions (such as imageline() , imagepolygon() , etc.), which can make the edges of drawn lines softer.
Simple answer: No.
Enabling imageantialias() only affects the pixel shading method when image is drawn, improves edge smoothness, but does not change the image size. The width and height of the image are still the pixel values obtained by calling imagesx() and imagesy() .
<?php
// Create a100x100True color image
$image = imagecreatetruecolor(100, 100);
// Turn on anti-aliasing
imageantialias($image, true);
// Draw a diagonal line
$color = imagecolorallocate($image, 255, 0, 0);
imageline($image, 10, 10, 90, 90, $color);
echo "Image Width：" . imagesx($image) . "\n";
echo "Image height：" . imagesy($image) . "\n";
// Output image
header("Content-Type: image/png");
imagepng($image);
imagedestroy($image);
?>
Run the code and the image size is still 100x100 pixels, but the edges of the drawn red lines will be smoother.
The image size will only change if:
Use imagecopyresampled() , imagecopyresampled() and other functions for scaling
Recreate the canvas and adjust the width and height
When loading an external image, the image is originally of different sizes
Anti-aliasing does not belong to the category of operation to change the image size.
imageantialias() only affects the rendering of pixels, smooths the edges
The width and height of the image will not be changed
If you want to change the image size, you need to use functions such as scaling.
By rationally utilizing anti-aliasing, the image lines can be more beautiful while keeping the original image size unchanged, which is a common technique when processing graphics.
