如何给图片加水印？

Question

如何在不影响源图像的情况下在图像上添加水印。

$SourceFile = '/uploadedimage/gallery/thumble/';
$DestinationFile = '/uploadedimage/gallery/thumble/image-watermark.jpg';
$WaterMarkText = 'Copyright appsbee.com';
watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile);



function watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile) {
   list($width, $height) = getimagesize($SourceFile);
   $image_p = imagecreatetruecolor($width, $height);
   $image = imagecreatefromjpeg($SourceFile);
   imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width, $height);
   $black = imagecolorallocate($image_p, 0, 0, 0);
   $font = 'arial.ttf';
   $font_size = 10;
   imagettftext($image_p, $font_size, 0, 10, 20, $black, $font, $WaterMarkText);
   if ($DestinationFile<>'') {
      imagejpeg ($image_p, $DestinationFile, 100);
   } else {
      header('Content-Type: image/jpeg');
      imagejpeg($image_p, null, 100);
   };
   imagedestroy($image);
   imagedestroy($image_p);
};

如果我这样做，缩略图文件夹中存在的图像就会受到影响。

Answer 1

使用这个类，在添加水印之前只需复制原始图像即可。

<?php
class Watermark{
    # given two images, return a blended watermarked image
    # given two images, return a blended watermarked image
    function create_watermark( $main_img_obj, $watermark_img_obj, $alpha_level = 100 ) {
        $alpha_level /= 100; # convert 0-100 (%) alpha to decimal
        # calculate our images dimensions
        $main_img_obj_w = imagesx( $main_img_obj );
        $main_img_obj_h = imagesy( $main_img_obj );
        $watermark_img_obj_w = imagesx( $watermark_img_obj );
        $watermark_img_obj_h = imagesy( $watermark_img_obj );
        # determine center position coordinates
        $main_img_obj_min_x = floor( ( $main_img_obj_w / 2 ) - ( $watermark_img_obj_w / 2 ) );
        $main_img_obj_max_x = ceil( ( $main_img_obj_w / 2 ) + ( $watermark_img_obj_w / 2 ) );
        $main_img_obj_min_y = floor( ( $main_img_obj_h / 2 ) - ( $watermark_img_obj_h / 2 ) );
        $main_img_obj_max_y = ceil( ( $main_img_obj_h / 2 ) + ( $watermark_img_obj_h / 2 ) );
        # create new image to hold merged changes
        $return_img = imagecreatetruecolor( $main_img_obj_w, $main_img_obj_h );
        # walk through main image
        for( $y = 0; $y < $main_img_obj_h; $y++ ) {
            for( $x = 0; $x < $main_img_obj_w; $x++ ) {
                $return_color     = NULL;

                # determine the correct pixel location within our watermark
                $watermark_x      = $x - $main_img_obj_min_x;
                $watermark_y      = $y - $main_img_obj_min_y;

                # fetch color information for both of our images
                $main_rgb = imagecolorsforindex( $main_img_obj, imagecolorat( $main_img_obj, $x, $y ) );

                # if our watermark has a non-transparent value at this pixel intersection
                # and we're still within the bounds of the watermark image
                if (  $watermark_x >= 0 && $watermark_x < $watermark_img_obj_w &&
                $watermark_y >= 0 && $watermark_y < $watermark_img_obj_h ) {
                    $watermark_rbg = imagecolorsforindex( $watermark_img_obj, imagecolorat( $watermark_img_obj, $watermark_x, $watermark_y ) );

                    # using image alpha, and user specified alpha, calculate average
                    $watermark_alpha  = round( ( ( 127 - $watermark_rbg['alpha'] ) / 127 ), 2 );
                    $watermark_alpha  = $watermark_alpha * $alpha_level;

                    # calculate the color 'average' between the two - taking into account the specified alpha level
                    $avg_red          = $this->_get_ave_color( $main_rgb['red'],            $watermark_rbg['red'],        $watermark_alpha );
                    $avg_green  = $this->_get_ave_color( $main_rgb['green'],      $watermark_rbg['green'],      $watermark_alpha );
                    $avg_blue         = $this->_get_ave_color( $main_rgb['blue'],      $watermark_rbg['blue'],       $watermark_alpha );

                    # calculate a color index value using the average RGB values we've determined
                    $return_color     = $this->_get_image_color( $return_img, $avg_red, $avg_green, $avg_blue );

                    # if we're not dealing with an average color here, then let's just copy over the main color
                } else {
                    $return_color     = imagecolorat( $main_img_obj, $x, $y );

                } # END if watermark

                # draw the appropriate color onto the return image
                imagesetpixel( $return_img, $x, $y, $return_color );

            } # END for each X pixel
        } # END for each Y pixel
        # return the resulting, watermarked image for display
        return $return_img;
    } # END create_watermark()

    # average two colors given an alpha
    function _get_ave_color( $color_a, $color_b, $alpha_level ) {
        return round( ( ( $color_a * ( 1 - $alpha_level ) ) + ( $color_b  * $alpha_level ) ) );
    } # END _get_ave_color()

    # return closest pallette-color match for RGB values
    function _get_image_color($im, $r, $g, $b) {
        $c=imagecolorexact($im, $r, $g, $b);
        if ($c!=-1) return $c;
        $c=imagecolorallocate($im, $r, $g, $b);
        if ($c!=-1) return $c;
        return imagecolorclosest($im, $r, $g, $b);
    } # EBD _get_image_color()
} # END watermark API
?>

这就是如何使用它

$watermark = new Watermark();
        $actual_image = imagecreatefromjpeg("images/$image_file");
        $watermark_image = imagecreatefrompng("images/water_mark.png");
        //create water marked image with 66% transparency
        $return_img_obj = $watermark->create_watermark( $actual_image, $watermark_image, 66 );

        //now save the updated image
        imagejpeg($return_img_obj,"images/$image_file1");

        //clear the memory
        imagedestroy($actual_image);
        imagedestroy($watermark_image);
        imagedestroy($return_img_obj);

Answer 2

不影响源图像。

要在不影响实际图像的情况下执行此操作，只需添加包含透明图像的 HTML 层即可。但这作为一种保护手段毫无用处，因为每个拥有一点点技术知识的人都可以在几秒钟内获取原始图像。

Answer 3

如果您不想影响源图像，那么我建议您将透明图像放在 HTML 中图像上方的绝对定位 div 中。这意味着您不必在每次页面加载时处理图像（因为您想保持原始图像完整），并且不必费力存储额外的图像。

Answer 4

使用GD图像库： http://php.net/manual/en/book.image .php

这样我就可以创建图像的网络水印版本并存储源图像。

除非您打算即时添加水印，在这种情况下，我不确定您是否可以轻松做到这一点。

Answer 5

从第一眼看来，我认为如果您没有向函数提供目标文件名，则这段代码不会影响源文件。