我正在尝试将Imagick :: steganoImage与Wikimedia Commons中的示例图像一起使用。如果我尝试显示水印的解码图像,则无论选择哪种图像源,我总是会在下面看到1像素的图像。任何人都可以帮助我了解为什么以及如何解决此问题?
<?
header("Content-Type: image/png");
// Create a new imagick object
$image = new Imagick('https://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Frostedbubble2.jpg/640px-Frostedbubble2.jpg');
$watermark = new Imagick('LABEL:Hello World!');
// The decoding process must "know" about the watermarks size, and starting
// pixel offset.
define('STEGANO_OFFSET', 64); // Secret offset
define('STEGANO_WIDTH', $watermark->getImageWidth());
define('STEGANO_HEIGHT', $watermark->getImageHeight());
$stegano = $image->steganoImage($watermark, STEGANO_OFFSET);
$stegano->writeImage('output.png');
$decoded = new Imagick();
$decoded->setSizeOffset(STEGANO_WIDTH, STEGANO_HEIGHT, STEGANO_OFFSET);
$decoded->readImage('STEGANO:output.png');
$decoded->writeImage('decoded.png');
// Show the output
$decoded->setImageFormat('png');
echo $decoded->getImageBlob();
?>
我也尝试过此页面上的代码https://www.geeksforgeeks.org/php-imagick-steganoimage-function/,并且正确显示了geeksforgeeks图像,但stegano图像显示为完全黑色。
<?php
// Create a new imagick object
$imagick = new Imagick(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-13.png');
// Create another Imagick object containing watermark
$watermark = new Imagick('label:This is my secret.');
// Hide $watermark inside $imagick
$imagick = $imagick->steganoImage($watermark, 64);
// Write image to the local folder
$imagick->writeImage('output.png');
// Set the offset
$imagick->setSizeOffset($watermark->getImageWidth(),
$watermark->getImageHeight(), 64);
// Read the encoded image and extract secret
$imagick->readImage('STEGANO:output.png');
// Show the output
$imagick->setImageFormat('png');
header("Content-Type: image/png");
echo $imagick->getImageBlob();
?>
看起来new Imagick('LABEL:Hello World!');
不再足以满足简单的标签要求。在读取标签之前,您需要设置画布的大小和点的大小。
define('STEGANO_OFFSET', 64); // Secret offset
define('STEGANO_WIDTH', 88);
define('STEGANO_HEIGHT', 14);
$watermark = new Imagick();
$watermark->setSize(STEGANO_WIDTH, STEGANO_HEIGHT);
$watermark->setPointSize(16);
$watermark->readImage('LABEL:Hello World!');
$stegano = $image->steganoImage($watermark, STEGANO_OFFSET);
我不能说何时/为什么改变了,但是如果您运行以下命令...
convert 'label:Hello World!' decoded.png
...您将拥有先前从STEGANO:
中提取的相同图像>