imageresolution

(PHP 7 >= 7.2.0)

imageresolutionGet or set the resolution of the image

Descrição

imageresolution ( resource $image ) : mixed
imageresolution ( resource $image , int $res_x [, int $res_y = $res_x ] ) : mixed

imageresolution() allows to set and get the resolution of an image in DPI (dots per inch). If none of the optional parameters is given, the current resolution is returned as indexed array. If only res_x is given, the horizontal and vertical resolution are set to this value. If both optional parameters are given, the horizontal and vertical resolution are set to these values, respectively.

The resolution is only used as meta information when images are read from and written to formats supporting this kind of information (curently PNG and JPEG). It does not affect any drawing operations. The default resolution for new images is 96 DPI.

Parâmetros

image

Um resource de imagem, retornado por funções de criação de imagens, como imagecreatetruecolor().

res_x

The horizontal resolution in DPI.

res_y

The vertical resolution in DPI.

Valor Retornado

When used as getter (first signature), it returns an indexed array of the horizontal and vertical resolution on success, ou false em caso de falha. When used as setter (second signature), it returns true on success, ou false em caso de falha.

Exemplos

Exemplo #1 Setting and getting the resolution of an image

<?php
$im 
imagecreatetruecolor(100100);
imageresolution($im200);
print_r(imageresolution($im));
imageresolution($im30072);
print_r(imageresolution($im));
?>

O exemplo acima irá imprimir:

Array
(
    [0] => 200
    [1] => 200
)
Array
(
    [0] => 300
    [1] => 72
)
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User Contributed Notes 1 note

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1
fernando dot fonseca at afteryou dot pt
1 year ago
It should be clear that the set version of the function doesn't change the image it self, just the resource in memory, which probably is fine if you didn't save the image yet. If your use case is for an image that is already on disk,  image you should always do something like:

imageresolution($img, 300, 300);
imagepng($img, $filname, $quality);
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