imagesetinterpolation()

(PHP 5 >= 5.5.0, PHP 7)

Set the interpolation method

说明

imagesetinterpolation(resource $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())返回的图象资源。

$method

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

• IMG_BELL: Bell filter.
• IMG_BESSEL: Bessel filter.
• IMG_BICUBIC: Bicubic interpolation.
• IMG_BICUBIC_FIXED: Fixed point implementation of the bicubic interpolation.
• IMG_BILINEAR_FIXED: Fixed point implementation of the bilinear interpolation(default(also on image creation)).
• IMG_BLACKMAN: Blackman window function.
• IMG_BOX: Box blur filter.
• IMG_BSPLINE: Spline interpolation.
• IMG_CATMULLROM: Cubic Hermite spline interpolation.
• IMG_GAUSSIAN: Gaussian function.
• IMG_GENERALIZED_CUBIC: Generalized cubic spline fractal interpolation.
• IMG_HERMITE: Hermite interpolation.
• IMG_HAMMING: Hamming filter.
• IMG_HANNING: Hanning filter.
• IMG_MITCHELL: Mitchell filter.
• IMG_POWER: Power interpolation.
• IMG_QUADRATIC: Inverse quadratic interpolation.
• IMG_SINC: Sinc function.
• IMG_NEAREST_NEIGHBOUR: Nearest neighbour interpolation.
• IMG_WEIGHTED4: Weighting filter.
• IMG_TRIANGLE: Triangle interpolation.

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

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:

• imageaffine()
• imagerotate()

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 );
?>