This will allow you to manipulate the thumbnail image ($imgJpeg) using the various gd commands:<?php if (($imgJpeg = exif_thumbnail($strImagePath)) === false) print "No Thumbnail!"; else $imgJpeg = imageCreateFromString($imgJpeg);?>
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
exif_thumbnail — 检索图像的嵌入式缩略图
$file,&$width = null,&$height = null,&$image_type = nullexif_thumbnail() 读取图像的嵌入式缩略图。
如果想通过该函数发送缩略图，应该使用 header() 函数发送 mimetype 信息。
exif_thumbnail() 不能创建图像但能确定它的尺寸。在这种情况下，返回值是
false，但会设置 width 和 height。
file图像文件的路径。可以是文件路径也可以是流 resource。
width返回缩略图的宽度。
height返回缩略图的高度。
image_type返回缩略图的图像类型。不是 TIFF 就是 JPEG。
返回嵌入式缩略图，如果图像不包含缩略图则返回 false。
| 版本 | 说明 |
|---|---|
| 7.2.0 |
file 参数现在支持本地文件和流资源。
|
示例 #1 exif_thumbnail() 示例
<?php
$image = exif_thumbnail('/path/to/image.jpg', $width, $height, $type);
if ($image!==false) {
header('Content-type: ' .image_type_to_mime_type($type));
echo $image;
exit;
} else {
// 没有可用的缩略图，这里处理错误
echo 'No thumbnail available';
}
?>注意:
如果传递流到此函数的
file，然后流必须是可寻找的。请注意，此函数返回后，文件指针位置不会改变。
This will allow you to manipulate the thumbnail image ($imgJpeg) using the various gd commands:<?php if (($imgJpeg = exif_thumbnail($strImagePath)) === false) print "No Thumbnail!"; else $imgJpeg = imageCreateFromString($imgJpeg);?>If you've edited the image with image editing software and it no longer contains an exif thumbnail, I've created a script that will add one back into it, using the "PHP Exif Library": http://pel.sourceforge.net/index.php<?phprequire_once('../PEL/PelJpeg.php');require_once('../PEL/PelIfd.php');$fullpath = 'images/DSC_0013c.JPG'; # path of source image (does not contain an exif thumbnail) $jpeg = new PelJpeg($fullpath); $exif = $jpeg->getExif(); $tiff = $exif->getTiff(); $ifd0 = $tiff->getIfd(); # need this so that we can later link it to the new IFD $ifd1 = $ifd0->getNextIfd();if (!$ifd1) { # Only create thumbnail if one doesn't exist (i.e. there is no IFD1) $ifd1 = new PelIfd(1); $ifd0->setNextIfd($ifd1); # point ifd0 to the new ifd1 (or else ifd1 will not be read) $original = ImageCreateFromString($jpeg->getBytes()); # create image resource of original $orig_w=imagesx($original); $orig_h=imagesy($original); $wmax = 160; $hmax = 120; if ($orig_w>$wmax || $orig_h>$hmax) { $thumb_w=$wmax; $thumb_h=$hmax; if ($thumb_w/$orig_w*$orig_h>$thumb_h) $thumb_w=round($thumb_h*$orig_w/$orig_h); # maintain aspect ratio else $thumb_h=round($thumb_w*$orig_h/$orig_w); } else { # only set the thumb's size if the original is larger than 'wmax'x'hmax' $thumb_w=$orig_w; $thumb_h=$orig_h; } # create image resource with thumbnail sizing $thumb=imagecreatetruecolor($thumb_w,$thumb_h); ## Resize original and copy to the blank thumb resource imagecopyresampled($thumb,$original, 0,0,0,0,$thumb_w,$thumb_h,$orig_w,$orig_h); # start writing output to buffer ob_start(); # outputs thumb resource contents to buffer ImageJpeg($thumb); # create PelDataWindow from buffer thumb contents (and end output to buffer) $window = new PelDataWindow(ob_get_clean()); if ($window) { $ifd1->setThumbnail($window); # set window data as thumbnail in ifd1 $outpath = $fullpath; # overwrite original jpg file file_put_contents($outpath, $jpeg->getBytes()); # write everything to output filename # Show thumbnail in file: echo '<img src="thumb_exif.php?image='.$outpath.'" border=0 alt="If you see this, it did not work"><br>'; }}else { echo 'ifd1 already exists! (IFD1 is where the thumbnail is stored)<br>';}?><?php # This is the code in thumb_exif.php : $imgdat = exif_thumbnail($_REQUEST['image'], $width, $height, $type); header('Content-type: ' . image_type_to_mime_type($type)); echo($imgdat);?>If you have a lot of such files, you can easily make a script that searches them out and adds thumbnails to their exif.use this if you want to embed a thumbnail directly on the HTML page without writing it first to a file:<?php$image = exif_thumbnail($file, $width, $height, $type);echo "<img width='$width' height='$height' src='data:image/gif;base64,".base64_encode($image)."'>";?>If you want to convert from TIFF to JPG you can use ImageMagick if it is installed in your server.<?php$exec = 'convert /path/to/file.tiff /path/to/file.jpg 2>&1';@exec($exec, $exec_output, $exec_retval);//possible errorprint_r($exec_output)?>Great that the thumbnail can be in TIFF format (f.i. Kodak cameras have embedded thumbnail in TIFF) BUT I have not been able to show TIFF as an embedded image in HTML (using the <IMG...> tag). There seems to be no function in PHP to change TIFF to, lets say, JPG. (imagecreatefromstring gives a 'unknown datatype' error for the TIFF stream. So below sample works great for JPEG embedded thumbnail, but not for TIFF embedded (but then, maybe I did something wrong?):test_exif.php:<HTML><HEAD> <TITLE>Test EXIF Read </TITLE></HEAD><BODY><?php$image='P0000614.JPG';echo("<B>". $image. "</B>:<BR><BR>\n");$exif = exif_read_data($image, 'ANY_TAG',true);if (!$exif===false){ echo("Image contains headers<br><br>"); echo("<A href=showthumb.php?image=" . $image ."> <IMG border=0 src=showthumb.php?image=" . $image ."></A><BR><BR>"); foreach ($exif as $key => $section) { foreach ($section as $name => $val) { echo "$key.$name: $val<br>\n"; } }}else{ echo("Sorry, image <B>".$image . "</B> does not contain (readable) EXIF data.");}?></BODY></HTML>showthumb.php:<?php$imgdat = exif_thumbnail($_REQUEST['image'],$width, $height, $type);header('Content-type: ' . image_type_to_mime_type($type));echo($imgdat);?>When clicking on the <A> opens the TIFF image in the program that windows assigned to this type, but the JPEG opens in the browser.I am using PHP 4.3.6 on windows iis 4 (yeah, I know.....)