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Introduction> <read_exif_data
Last updated: Fri, 06 Nov 2009

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Image Processing and GD



Introduction> <read_exif_data
Last updated: Fri, 06 Nov 2009
 
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GD
jordan at jkdesign dot org
08-Sep-2009 01:09
Building on Ashley's example, here's an example of some code that grabs an existing image file and outputs an html img tag with the contents. I found it useful because I needed to not broadcast the filenames.

<?php
$file = 'images/01.png';
$image = imagecreatefrompng($file);
imagealphablending($image, false);
imagesavealpha($image, true);

// start buffering
ob_start();
imagepng($image);
$contents =  ob_get_contents();
ob_end_clean();

echo "<img src='data:image/png;base64,".base64_encode($contents)."' />";

imagedestroy($image);
?>
scurvysquid at yahoo dot com
04-May-2009 10:08
to address Thomas' note about exif data, exif is only valid for .tiff and .jpg files.    As always, it's up to the individual to make the call but I personally would prefer to create an abstraction layer to work for all images, and relying on exif data means you need to limit your allowed image types.  I've heard some great things about the GD library and found them to all be true in my own use of it, losing the nominally useful data specific to jpegs and pngs is not a sufficient reason alone to convince me to use imagemagick instead.
Thomas
11-Dec-2008 12:05
You know, maybe this goes without saying, but I thought I would drop a note in here.  When developing code to resize images, it is best not to use GD.  When using the current GD methodologies, you are reading content from an image and manipulating it.  By then writing that content to a brand new file, you are losing the EXIF data.

For purposes when you want to retain EXIF data, it is recommended that you compile in and use the PECL Imagick extension.  It has great resizing methods built right in and the EXIF data is retained.
code at ashleyhunt dot co dot uk
24-Oct-2008 04:02
I have been looking to send the output from GD to a text string without proxying via a file or to a browser.

I have come up with a solution.

This code buffers the output between the ob_start() and ob_end() functions into ob_get_contents()

See the example below

<?php
// Create a test source image for this example
$im = imagecreatetruecolor(300, 50);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5,  'A Simple Text String', $text_color);

// start buffering
ob_start();
// output jpeg (or any other chosen) format & quality
imagejpeg($im, NULL, 85);
// capture output to string
$contents = ob_get_contents();
// end capture
ob_end_clean();

// be tidy; free up memory
imagedestroy($im);

// lastly (for the example) we are writing the string to a file
$fh = fopen("./temp/img.jpg", "a+" );
    fwrite( $fh, $contents );
fclose( $fh );
?>

Enjoy!
Ashley
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Introduction> <read_exif_data
Last updated: Fri, 06 Nov 2009
 
 
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