PHP image processing functions to implement various image manipulation techniques

PHP image processing functions are a series of functions provided by PHP for performing various operations on images. With the help of these functions, we can implement various image manipulation functions such as scaling, cropping, rotating, and adding watermarks. This article will introduce some techniques for using PHP image processing functions to achieve these functions.

1. Zoom pictures

Zooming pictures is one of the most common picture operation functions. PHP provides the function imagecopyresampled() to scale the image to the specified size.

$srcImage = imagecreatefromjpeg('image.jpg');
$dstImage = imagecreatetruecolor($newWidth, $newHeight);
imagecopyresampled($dstImage, $srcImage, 0, 0, 0, 0, $newWidth, $newHeight, $srcWidth, $srcHeight);
imagejpeg($dstImage, 'new_image.jpg');

In the above code, first use the imagecreatefromjpeg() function to read the image to be processed, and then use the imagecreatetruecolor() function to create a canvas of the scaled image , then use the imagecopyresampled() function to scale the original image to the specified size, and finally use the imagejpeg() function to save the scaled image to a file.

2. Crop the picture

Crop the picture means to intercept the picture according to the specified size. PHP provides the function imagecrop() for cropping images.

$srcImage = imagecreatefromjpeg('image.jpg');
$dstImage = imagecrop($srcImage, ['x' => $x, 'y' => $y, 'width' => $width, 'height' => $height]);
imagejpeg($dstImage, 'new_image.jpg');

In the above code, first use the imagecreatefromjpeg() function to read the image to be processed, and then use the imagecrop() function to process the image according to the specified size. Crop, and finally use the imagejpeg() function to save the cropped image to a file.

3. Rotate the picture

Rotating the picture means rotating the picture according to the specified angle. PHP provides the function imagerotate() for image rotation.

$srcImage = imagecreatefromjpeg('image.jpg');
$dstImage = imagerotate($srcImage, $angle, 0);
imagejpeg($dstImage, 'new_image.jpg');

In the above code, first use the imagecreatefromjpeg() function to read the image to be processed, and then use the imagerotate() function to rotate the image according to the specified angle. Rotate, and finally use the imagejpeg() function to save the rotated image to a file.

4. Adding watermark

Adding watermark means adding some identification information to the picture, such as company LOGO, copyright information, etc. PHP provides the functions imagecopy() and imagecopymerge() to implement the watermark function of images.

$srcImage = imagecreatefromjpeg('image.jpg');
$watermarkImage = imagecreatefrompng('watermark.png');
imagecopy($srcImage, $watermarkImage, $x, $y, 0, 0, $watermarkWidth, $watermarkHeight);
imagejpeg($srcImage, 'new_image.jpg');

In the above code, first use the imagecreatefromjpeg() function to read the image to be processed and the imagecreatefrompng() function to read the watermark image, and then use ## The #imagecopy() function adds the watermark image to the specified location of the original image, and finally uses the imagejpeg() function to save the image with the watermark to a file.

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