note 84762 modified in function.exif-read-data by yannick
| From: | yannick@php.net | Date: | Thu, 07 Aug 2008 13:56:00 +0000 |
| Subject: | note 84762 modified in function.exif-read-data by yannick | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-143273@lists.php.net to get a copy of this message | ||
I wanted some quick and easy functions for computing the shutter speed and f-stop. I couldn't
find any anywhere, so I made some. It took some research :
<?php
function exif_get_float($value) {
$pos = strpos($value, '/');
if ($pos === false) return (float) $value;
$a = (float) substr($value, 0, $pos);
$b = (float) substr($value, $pos+1);
return ($b == 0) ? ($a) : ($a / $b);
}
function exif_get_shutter(&$exif) {
if (!isset($exif['ShutterSpeedValue'])) return false;
$apex = exif_get_float($exif['ShutterSpeedValue']);
$shutter = pow(2, -$apex);
if ($shutter == 0) return false;
if ($shutter >= 1) return round($shutter) . 's';
return '1/' . round(1 / $shutter) . 's';
}
function exif_get_fstop(&$exif) {
if (!isset($exif['ApertureValue'])) return false;
$apex = exif_get_float($exif['ApertureValue']);
$fstop = pow(2, $apex/2);
if ($fstop == 0) return false;
return 'f/' . round($fstop,1);
}
?>
--was--
I wanted some quick and easy functions for computing the shutter speed and f-stop. I couldn't
find any anywhere, so I made some. It took some research
function exif_get_float($value) {
$pos = strpos($value, '/');
if ($pos === false) return (float) $value;
$a = (float) substr($value, 0, $pos);
$b = (float) substr($value, $pos+1);
return ($b == 0) ? ($a) : ($a / $b);
}
function exif_get_shutter(&$exif) {
if (!isset($exif['ShutterSpeedValue'])) return false;
$apex = exif_get_float($exif['ShutterSpeedValue']);
$shutter = pow(2, -$apex);
if ($shutter == 0) return false;
if ($shutter >= 1) return round($shutter) . 's';
return '1/' . round(1 / $shutter) . 's';
}
function exif_get_fstop(&$exif) {
if (!isset($exif['ApertureValue'])) return false;
$apex = exif_get_float($exif['ApertureValue']);
$fstop = pow(2, $apex/2);
if ($fstop == 0) return false;
return 'f/' . round($fstop,1);
}
http://php.net/manual/en/function.exif-read-data.php