GD and Image Functions
PHP Manual

imagesetinterpolation

Set the interpolation method

Description

bool imagesetinterpolation ( resource $image [, int $method = IMG_BILINEAR_FIXED ] )

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

Parameters

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor.

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.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #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 ...
?>

Notes

Changing the interpolation method affects the following functions when rendering:

  • imageaffine
  • imagerotate
  • imagescale