SETS the interpolation method, setting an interpolation method affects the rendering of various functions in GD, such as the imagerotate function.
The imagerotate function has already been seen on the previous page.
<?php
bool imagesetinterpolation( GdImage $image,
int $method = IMG_BILINEAR_FIXED )
where,
$image = The image identifier
$method = The interpolation method
( SEE the below TABLE )
?>
| IMAGE INTERPOLATION CONSTANTS | ||
| CONSTANT | VALUE | MEANING |
| IMG_BELL | 1 | Bell filter |
| IMG_BESSEL | 2 | Bessel filter |
| IMG_BILINEAR_FIXED | 3 | Fixed point implementation of the bilinear interpolation |
| IMG_BICUBIC | 4 | Bicubic interpolation |
| IMG_BICUBIC_FIXED | 5 | Fixed point implementation of the bicubic interpolation |
| IMG_BLACKMAN | 6 | Blackman window function |
| IMG_BOX | 7 | Box blur filter |
| IMG_BSPLINE | 8 | Spline interpolation |
| IMG_CATMULLROM | 9 | Cubic Hermite spline interpolation |
| IMG_GAUSSIAN | 10 | Gaussian function |
| IMG_GENERALIZED_CUBIC | 11 | Generalized cubic spline fractal interpolation |
| IMG_HERMITE | 12 | Hermite interpolation |
| IMG_HAMMING | 13 | Hamming filter |
| IMG_HANNING | 14 | Hanning filter |
| IMG_MITCHELL | 15 | Mitchell filter |
| IMG_NEAREST_NEIGHBOUR | 16 | Nearest neighbour interpolation |
| IMG_POWER | 17 | Power interpolation |
| IMG_QUADRATIC | 18 | Inverse quadratic interpolation |
| IMG_SINC | 19 | Sinc function |
| IMG_TRIANGLE | 20 | Triangle interpolation |
| IMG_WEIGHTED4 | 21 | Weighting filter |
| ed48 | ||
EXERCISE
<?php
echo 'PHP VERSION: ' . PHP_VERSION . '<br><br>';
$image01 = 'gif/GIF 028 01.gif';
// Ocaporã - PALETTE IMAGE
$intrp01 = [
"IMG_BELL" => IMG_BELL,
"IMG_BESSEL" => IMG_BESSEL,
"IMG_BILINEAR_FIXED" => IMG_BILINEAR_FIXED,
"IMG_BICUBIC" => IMG_BICUBIC,
"IMG_BICUBIC_FIXED" => IMG_BICUBIC_FIXED,
"IMG_BLACKMAN" => IMG_BLACKMAN,
"IMG_BOX" => IMG_BOX,
"IMG_BSPLINE" => IMG_BSPLINE,
"IMG_CATMULLROM" => IMG_CATMULLROM,
"IMG_GAUSSIAN" => IMG_GAUSSIAN,
"IMG_GENERALIZED_CUBIC" => IMG_GENERALIZED_CUBIC,
"IMG_HERMITE" => IMG_HERMITE,
"IMG_HAMMING" => IMG_HAMMING,
"IMG_HANNING" => IMG_HANNING,
"IMG_MITCHELL" => IMG_MITCHELL,
"IMG_NEAREST_NEIGHBOUR" => IMG_NEAREST_NEIGHBOUR,
"IMG_POWER" => IMG_POWER,
"IMG_QUADRATIC" => IMG_QUADRATIC,
"IMG_SINC" => IMG_SINC,
"IMG_TRIANGLE" => IMG_TRIANGLE,
"IMG_WEIGHTED4" => IMG_WEIGHTED4
];
echo $image01 . '<br><br>Existing Image</span>'; ?><br><br>
<img src="<?php echo $image01; ?>"
alt="<?php echo $image01; ?>"
title="<?php echo $image01; ?>"><br><br>
<?php
$id_img01 = imagecreatefromgif($image01);
$bkg_01 = 0xeeeeee;
foreach($intrp01 as $method01 => $meth01 )
{
$int_image01 = 'gif/GIF 028 01-' . $method01 . '.gif';
$b01 = imagesetinterpolation($id_img01, $meth01);
imagegif($id_img01, $int_image01);
echo '<br><br>' . basename($int_image01) . '<br><br>
Filter: ' . $method01 . '<br>';
?>
<img src="<?php echo $int_image01; ?>"
alt="<?php echo $int_image01; ?>"
title="<?php echo $int_image01; ?>"><br><br>
<?php
if(PHP_MAJOR_VERSION >= 8)
{
echo $method01 . ' = ' . imagegetinterpolation($id_img01);
echo '<br><br>';
}
?>
<?php
}
?>
EXERCISE
<?php
echo 'PHP VERSION: ' . PHP_VERSION . '<br><br>';
$tst_img = "gif/GIF 021 02.gif";
// April 25th bridge(POR) - PALETTE IMAGE
$id_org = imagecreatefromgif($tst_img);
$intrp = [ IMG_BELL, IMG_BESSEL, IMG_BICUBIC,
IMG_BICUBIC_FIXED, IMG_BILINEAR_FIXED,
IMG_BLACKMAN, IMG_BOX, IMG_BSPLINE,
IMG_CATMULLROM, IMG_GAUSSIAN,
IMG_GENERALIZED_CUBIC, IMG_HERMITE,
IMG_HAMMING, IMG_HANNING, IMG_MITCHELL,
IMG_POWER, IMG_QUADRATIC, IMG_SINC,
IMG_NEAREST_NEIGHBOUR, IMG_WEIGHTED4,
IMG_TRIANGLE ];
$intrs = [ "BELL", "BESSEL", "BICUBIC",
"BICUBIC_FIXED", "BILINEAR_FIXED",
"BLACKMAN", "BOX", "BSPLINE",
"CATMULLROM", "GAUSSIAN",
"GENERALIZED_CUBIC", "HERMITE",
"HAMMING", "HANNING", "MITCHELL",
"POWER", "QUADRATIC", "SINC",
"NEAREST_NEIGHBOUR", "WEIGHTED4",
"TRIANGLE" ];
echo $tst_img; ?>
<br><br><img src="<?php echo $tst_img; ?>"
alt="<?php echo $tst_img; ?>" width="400"><br><br><br><br>
<?php
$ang_r2 = mt_rand(-30, 30);
// rotation angle in the numeric range [-30, 30}
$bkg_2 = 0xeeeeee;
// background color
$trn = 1;
$rnd_intrp = mt_rand(0, 20);
{
imagesetinterpolation($id_org, $intrp[$rnd_intrp]);
$id_dst2 = imagerotate($id_org, $ang_r2, $bkg_2, $trn );
$dst2_img = 'gif/GIF 021 02-' . $intrs[$rnd_intrp] . '.gif';
imagegif ($id_dst2, $dst2_img);
}
echo basename($dst2_img) . '<br><br>
Rotation angle: ' . $ang_r2 . '°'; ?>
<br><br><img src="<?php echo $dst2_img; ?>"
alt="<?php echo $dst2_img; ?>" width="400">
EXERCISE
<?php
echo 'PHP VERSION: ' . PHP_VERSION . '<br><br>';
$tst_img = "bmp/BMP 008 01.bmp";
// TRUECOLOR IMAGE
$id_org = imagecreatefrombmp($tst_img);
$intrp = [ IMG_BELL, IMG_BESSEL, IMG_BICUBIC,
IMG_BICUBIC_FIXED, IMG_BILINEAR_FIXED,
IMG_BLACKMAN, IMG_BOX, IMG_BSPLINE,
IMG_CATMULLROM, IMG_GAUSSIAN,
IMG_GENERALIZED_CUBIC, IMG_HERMITE,
IMG_HAMMING, IMG_HANNING, IMG_MITCHELL,
IMG_POWER, IMG_QUADRATIC, IMG_SINC,
IMG_NEAREST_NEIGHBOUR, IMG_WEIGHTED4,
IMG_TRIANGLE ];
$intrs = [ "BELL", "BESSEL", "BICUBIC",
"BICUBIC_FIXED", "BILINEAR_FIXED",
"BLACKMAN", "BOX", "BSPLINE",
"CATMULLROM", "GAUSSIAN",
"GENERALIZED_CUBIC", "HERMITE",
"HAMMING", "HANNING", "MITCHELL",
"POWER", "QUADRATIC", "SINC",
"NEAREST_NEIGHBOUR", "WEIGHTED4",
"TRIANGLE" ];
echo $tst_img; ?>
<br><br><img src="<?php echo $tst_img; ?>"
alt="<?php echo $tst_img; ?>"><br><br><br><br>
<?php
$ang_r3 = mt_rand(-30, 30);
// rotation angle in the numeric range [-30, 30}
$bkg_3 = 0xeeeeee;
// background color
$trn = 1;
$rnd_intrp = mt_rand(0, 20);
{
imagesetinterpolation($id_org, $intrp[$rnd_intrp]);
$id_dst3 = imagerotate($id_org, $ang_r3, $bkg_3, $trn );
$dst3_img = 'bmp/BMP 008 01.bmp-' . $intrs[$rnd_intrp] . '.bmp';
imagebmp ($id_dst3, $dst3_img);
}
echo basename($dst3_img) . '<br><br>
Rotation angle: ' . $ang_r3 . '°'; ?>
<br><br><img src="<?php echo $dst3_img; ?>"
alt="<?php echo $dst3_img; ?>">
