1. 添加水印
经测试,效果不错,jpg 尤佳:
<?php define('WATERMARK_OVERLAY_IMAGE', $_SERVER['DOCUMENT_ROOT'] .'/public/assets/logo.png'); /* * $img 是图片的绝对路径 * 用法:watermark($_SERVER['DOCUMENT_ROOT'] .'/public/images/bg.jpg'); */ function watermark($img) { ob_start(); // Set content type header('Content-type: image/jpg'); // Cerate watermark $wm = imagecreatefrompng(WATERMARK_OVERLAY_IMAGE); // getting dimensions of watermark image $wm_size = getimagesize(WATERMARK_OVERLAY_IMAGE); // Create image $image = imagecreatefromjpeg($img); // Get image size $size = getimagesize($img); // placing the watermark center $dest_x = ($size[0] - $wm_size[0])/2; $dest_y = ($size[1] - $wm_size[1])/2; // blending the images together imagealphablending($image, true); imagealphablending($wm, true); // creating the new image imagecopy($image, $wm, $dest_x, $dest_y, 0, 0, $wm_size[0] , $wm_size[1]); // Send image to the browser imagejpeg($image, null, 100); //Save image in cache // destroy image and watermak imagedestroy($image); imagedestroy($wm); $output = ob_get_contents(); ob_end_clean(); unlink($img); $size = strlen($output); $ftp = @fopen($img, "a"); fwrite($ftp,$output); fclose($ftp); }
2. png2jpg
You need to create a fresh image with a white (or whatever you want) background and copy the none-transparent pixels from the png to that image:
function png2jpg($originalFile, $outputFile, $quality) { $source = imagecreatefrompng($originalFile); $image = imagecreatetruecolor(imagesx($source), imagesy($source)); $white = imagecolorallocate($image, 255, 255, 255); imagefill($image, 0, 0, $white); imagecopy($image, $source, 0, 0, 0, 0, imagesx($image), imagesy($image)); imagejpeg($image, $outputFile, $quality); imagedestroy($image); imagedestroy($source); }3. gif2jpg
For those interested in my solution, I simply used the built in GD PHP functions. I have little experience dealing with gif files so I was expecting this to be difficult. The fact of the matter is the CodeIgniter Image_lib and extended library (Which I never got to work properly) is overkill for this.
$image = imagecreatefromgif($path_to_gif_image); imagejpeg($image, $output_path_with_jpg_extension);4. Resizing images with PHP
The following script will easily allow you to resize images using PHP and the GD library. If you’re looking to resize uploaded images or easily generate thumbnails give it a try
Update: Looking to resize transparent PNG’s and GIF’s? We’ve updated our original code, take a look at http://www.white-hat-web-design.co.uk/blog/retaining-transparency-with-php-image-resizing/
Save the code from the ‘the code’ section below as SimpleImage.php and take a look at the following examples of how to use the script.
The first example below will load a file named picture.jpg resize it to 250 pixels wide and 400 pixels high and resave it as picture2.jpg
<?php include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resize(250,400); $image->save('picture2.jpg'); ?> If you want to resize to a specifed width but keep the dimensions ratio the same then the script can work out the required height for you, just use the resizeToWidth function. <?php include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToWidth(250); $image->save('picture2.jpg'); ?> You may wish to scale an image to a specified percentage like the following which will resize the image to 50% of its original width and height <?php include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->scale(50); $image->save('picture2.jpg'); ?>You can of course do more than one thing at once. The following example will create two new images with heights of 200 pixels and 500 pixels
<?php include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToHeight(500); $image->save('picture2.jpg'); $image->resizeToHeight(200); $image->save('picture3.jpg'); ?>The output function lets you output the image straight to the browser without having to save the file. Its useful for on the fly thumbnail generation
<?php header('Content-Type: image/jpeg'); include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToWidth(150); $image->output(); ?>The following example will resize and save an image which has been uploaded via a form
<?php if( isset($_POST['submit']) ) { include('SimpleImage.php'); $image = new SimpleImage(); $image->load($_FILES['uploaded_image']['tmp_name']); $image->resizeToWidth(150); $image->output(); } else { ?> <form action="upload.php" method="post" enctype="multipart/form-data"> <input type="file" name="uploaded_image" /> <input type="submit" name="submit" value="Upload" /> </form> <?php } ?>This script will eventually be developed further to include functions for easily sharpening, bluring, cropping, brightening and colouring images.
from: http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/