Question

我需要使用imagick和php将TIFF格式的上传图像调整为小于95 kB的特定文件大小。有人可以告诉我最好的方法来使大小小于95kb吗？
我正在使用下面的代码，但是有时使用此代码，我得到的图像大小大于95kb？

$filename = "test.jpg";
$image = new Imagick($filename);
$image->setImageCompressionQuality(int(40));
$img =  preg_replace('/\\.[^.\\s]{3,4}$/', '', $filename).".tiff";
$image->writeImage($img);

Answer 1

Imagick具有此功能。

$filename = "test.jpg";
$image = new Imagick($filename);
// Setting your default compression
$compression_value = int(40);
// Imagick needs to know how to compress
$image->setImageCompression(COMPRESSION_JPEG);
$image->setImageCompressionQuality($compression_value);
// getImageLength gets the length of the file in bytes.
while ($image->getImageLength() > 95000) {
    $compression_value = $compression_value +1;
    $image->setImageCompressionQuality($compression_value);
}
$img =  preg_replace('/\\.[^.\\s]{3,4}$/', '', $filename).".tiff";
$image->writeImage($img);

注意：这就是说，您可能要设置最大循环数，因为它可以使压缩水平越来越高，而收益越高则递减率越高。通常您不会超过100，所以这是我的建议。如果无法将图像压缩到95k，则可能要在某个位置停止。

Answer 2

基于我在Danack和我之间的另一个问题（尚未进行测试，仍在进行中）的讨论，给出了一个更为有效的答案（但更为复杂）。

$filename = "test.jpg";
$image = new Imagick($filename);
// Setting your default compression
$height = $image->getImageHeight();
$width = $image->getImageWidth();
$raw_size = $height * $width;


// Imagick needs to know how to compress
$image->setImageCompression(COMPRESSION_JPEG);
$image->setImageCompressionQuality($compression_value);
// 80 compression shaves off about 40% of file size. Using that to estimate 
// 1% reduction for every 2 compression. This should be refined
// as more data is gained for your specific scenario.
 $compression_value = int(190/$raw_size);
// getImageLength gets the length of the file in bytes.
loop_refine($compression_value, $image);
while () {

}
// This reduces our size just a little more
$image->stripImage();
$img =  preg_replace('/\\.[^.\\s]{3,4}$/', '', $filename).".tiff";
$image->writeImage($img);

function loop_refine(&$compression_value, &$image){
    if ($image->getImageLength() > 95000 && $compression_value < 101){
        reduce_image_size($compression_value, $image);
    } elseif ($image->getImageLength() > 92000 && $compression_value < 101){
        increase_image_size($compression_value, $image);
    } else {
        return;
    }
}
function reduce_image_size(&$compression_value, &$image){
    $compression_value = $compression_value + int((101 - $compression_value)/2);
    $image->setImageCompressionQuality($compression_value);
    loop_refine($compression_value, $image);
}
function increase_image_size(&$compression_value, &$image){
    $compression_value = $compression_value - int((101- $compression_value)/4);
    $image->setImageCompressionQuality($compression_value);
    loop_refine($compression_value, $image);
}

Answer 3

尝试此代码...

// File and new size image

$filename = 'imagename.jpg';
$percent = 0.4;

// Content type

header('Content-Type: image/jpeg');

// Get new sizes image

list($width, $height) = getimagesize($filename);
$newwidth = $width * $percent;
$newheight = $height * $percent;

// Load image

$thumb = imagecreatetruecolor($newwidth, $newheight);
$source = imagecreatefromjpeg($filename);

// Resize image

imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

// result 

imagejpeg($thumb);

使用ImageMagick和PHP

3 个答案: