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imagesetinterpolation

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

imagesetinterpolationSet the interpolation method

说明

imagesetinterpolation(GdImage $image, int $method = IMG_BILINEAR_FIXED): bool

Sets the interpolation method, setting an interpolation method affects the rendering of various functions in GD, such as the imagerotate() function.

参数

image

由图象创建函数(例如imagecreatetruecolor())返回的 GdImage 对象。

method

The interpolation method, which can be one of the following:

返回值

成功时返回 true, 或者在失败时返回 false

更新日志

版本 说明
8.0.0 image 现在需要 GdImage 实例;之前需要有效的 gd resource

示例

示例 #1 imagesetinterpolation() example

<?php
// Load an image
$im = imagecreate(500, 500);

// By default interpolation is IMG_BILINEAR_FIXED, switch
// to use the 'Mitchell' filter:
imagesetinterpolation($im, IMG_MITCHELL);

// Continue to work with $im ...
?>

注释

Changing the interpolation method affects the following functions when rendering:

参见

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User Contributed Notes 1 note

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-1
shaun at slickdesign dot com dot au
6 years ago
Setting the interpolation does not carry through to any images created by imageaffine() or imagerotate(). It defaults to IMG_BILINEAR_FIXED and would need to be set on each generated image as required.

<?php
imagesetinterpolation
( $image, IMG_NEAREST_NEIGHBOUR );

// Rotated using IMG_NEAREST_NEIGHBOUR
$rotated = imagerotate( $image, 45, $transparent );

// Rotated using IMG_BILINEAR_FIXED
$rotated_again = imagerotate( $rotated, 45, $transparent );
?>

Setting the interpolation to IMG_NEAREST_NEIGHBOUR can help to preserve details and prevent sampling issues when rotating an image at 90 degree increments, including when rotating clockwise.

<?php
// Rotated image can appear blurred and on a slight angle.
$rotated = imagerotate( $image, -360, $transparent );

// Similar to starting Image although it may still show a background or be on a slight angle.
imagesetinterpolation( $image, IMG_NEAREST_NEIGHBOUR );
$rotated = imagerotate( $image, -360, $transparent );
?>
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