Pixel Punching PHP GD and Imagick 

Introduction  Working with pictures is a must anymore to complete the whole social experience of the internet.  You will not memorize the API’s tonight. There are too many and they are full of weird.  Hopefully you get a feeling of knowing what you can/cannot do easy and know where to look to implement further. 

PHP Graphic Library Overview  GD  Imagick  GMagick  Ignored because it is [just] a fork of Imagick with the design principles of never advancing API’s for sake of backwards compat. A noble goal but...  Could not find a working Windows build anyway.  Cairo  Vector graphics, neato stuff, but...  Not enough actual filled out documentation, so I haven’t really used it and I'd sound like a retard talking about it.  Exif  Not actually an image library. A JPEG meta data reading library. It cannot even write. 

GD Graphics Library  Graphics Draw Library  Originally GIF Draw.  Was unable to actually render GIF’s from 1999 to 2004 because the GIF license was revoked. In 2004 the GIF patent expired.  Has bindings for nearly every language [that matters] ever.  Not really worked on anymore. PHP maintains their copy that is how we get along with that.  Sort of a “Copy and Paste” based system. 

PHP GD Pro/Con Pros  Comes bundled with PHP.  Compiles anywhere first time.  Lightweight for lightweight work.  Most web hosts will have it. Cons  Cumbersome to do advanced work with.  OLD style API (pre- OOP) – Procedural  Larger jobs consume LOTS of resources.  Terribad at Alpha Channel (opacity) 

ImageMagick  Huge graphics library able to write support nearly any image format you could care to think of.  Basically, Photoshop for your CLI.  Layer based system.  Has support for OpenCL  Meaning, it can use your GPU to do stuff. 

Imagick Pro/Con Pros  Lots of advanced features.  Decent OOP interface. *  Does heavy lifting with ease. Cons  Arse and a half to compile the dependencies.  Method names a bit goofy. * 

Uploading Tangent: Getting images (or whatever) to the PHPs. 

The Server  PHP.INI  file_uploads = On  Enables uploads  upload_max_filesize = 10M  How large each file can be.  post_max_size = 10M  Technically this would limit you to files slightly less than 10M as there is other post data involved in the request taking up space.  max_file_uploads = 10  How many files per form. 

The Form  enctype is the only real key here.   Allows multiple files with ease.  $_FILES[‘something’][‘name’][\d+] 

The Upload $_FILES[‘derp’] Array ( [name] => Array ( [0] => hail__king_arthas_menethil.jpg [1] => zInfg.jpg [2] => f6Kik.jpg ) [type] => Array ( [0] => image/jpeg [1] => image/jpeg [2] => image/jpeg ) [tmp_name] => Array ( [0] => C:\Users\bob\AppData\Local\Temp\phpA18.tmp [1] => C:\Users\bob\AppData\Local\Temp\phpA19.tmp [2] => C:\Users\bob\AppData\Local\Temp\phpA1A.tmp ) [error] => Array ( [0] => 0 [1] => 0 [2] => 0 ) [size] => Array ( [0] => 235038 [1] => 176960 [2] => 61551 ) ) 

Manipulation Simple Image Tasks 

Basic Geometric Tasks  Cropping  Resizing  Scaling  Thumbnailing  GD  imagecopyresampled  We use this with different maths to do it all.  Imagick  cropImage  resizeImage  thumbnailImage 

Cropping That’s a nice photo, too bad it has my Ex in it...  Cutting an image smaller than it already is, much like cutting a picture out of the newspaper or magazine.  Need to know:  The X and Y coords of the top left of the cutting box.  The Width and Height you want the final cut of or the X and Y of the lower right of the cutting box.  Both libraries use X,Y,W,H so you will then be calculating the W and H yourself if you use the lower right corner. 

Cropping Images - GD  PNG, 640x480. We want the region at 12x32+200x200. $old = imagecreatefrompng($filename);  Create Desired Size Canvas $new = imagecreatetruecolor(200,200);  Copy desired region from old to new. Save. Free Resources. imagecopyresampled( $new,$old, 0,0, 12,32, 200,200, 200,200 ); imagepng($new,$filename); imagedestroy($old); imagedestroy($new); 

Cropping Images - Imagick  PNG, 640x480. We want the region at 12x32+200x200. $img = new Imagick($filename);  Crop It. $img->cropImage(200,200, 12,32);  Save. Free Resources. $img->writeImage($filename); $img->destroy(); 

Resizing A massage for pixels  Changing the Width and Height of an image to be a new Width and Height.  Aspect ratio? Honey badger don’t care.  Need to know your desired width and height. 

Resizing Images - GD  PNG, 640x480. We want to resize this to 200x200. $old = imagecreatefrompng($filename); $w = imagesx($old); $h = imagesy($old);  Create Desired Size Canvas $new = imagecreatetruecolor(200,200);  Copy desired region from old to new. Save. Free Resources. imagecopyresampled( $new, $old, 0,0 ,0,0, 200,200, $w,$h ); imagepng($new,$filename); imagedestroy($old); imagedestroy($new); 

Resizing Images - Imagick  PNG, 640x480. We want to resize this to 200x200. $img = new Imagick($filename);  Resize it. $img->resizeImage( 200,200, Imagick::FILTER_LANCZOS, 1 );  Save. Free Resources. $img->writeImage($filename); $img->destroy(); 

Scaling I need this to fit in that frame...  Fit an image into a desired Width and Height, but keeping the aspect ratio to not distort the image.  One dimension will be smaller than the requested size, unless it was a perfect square and you asked for a perfect square.  Same as resize code but with an added magical function for maths.  [show the fine people a magical method for scaling bob]  Need to know the desired width and height and the current width and height of the image.  Proportions. If an image is 400x300, and we want it to fit in 100x100 w1 w2 400 100 -- = -- --- = --- (100*300) / 400 = h = 75 100x75 h1 h2 300 h 

Scaling Images - GD  PNG, 640x480. We want to scale this to fit in 200x200. $old = imagecreatefrompng($filename); list($w,$h) = array(imagesx($old),imagesy($old)); list($nw,$nh) = lol_magic_scale($w,$h,200,200);  Create Desired Size Canvas $new = imagecreatetruecolor($nw,$nh);  Copy. Save. Free. imagecopyresampled( $new, $old, 0,0 ,0,0, $nw,$nh, $w,$h ); imagepng($new,$filename); imagedestroy($old); imagedestroy($new); 

Scaling Images - Imagick  PNG, 640x480. We want to scale this to fit in 200x200. $img = new Imagick($filename);  Resize it. $img->resizeImage( 200,200, Imagick::FILTER_LANCZOS, 1, true );  Save. Free Resources. $img->writeImage($filename); $img->destroy(); 

Thumbnailing Photo gallery previews, etc.  Creating a useful representation that is fill fit to a size, then with the excess cropped off.  Fill fit to the smallest dimension.  Crop excess in longest dimension.  For demo simplicity, our resulting image is a perfect square.  Need to know your desired size, and the image current width and height. 

Thumbnailing Images - GD $old = imagecreatefrompng($filename); $w = imagesx($old); $h = imagesy($old)); // calculate fill fit if($w > $h) list($nw,$nh) = lol_magic_scale($w,$h, -1,200); else list($nw,$nh) = lol_magic_scale($w,$h, 200,-1); // scale it down. $new = imagecreatetruecolor($nw,$nh); imagecopyresampled( $new, $old, 0,0 ,0,0, $nw,$nh, $w,$h ); imagedestroy($old); unset($old); // crop off the excess from either end to center it and fit it $last = imagecreatetruecolor(200,200); imagecopyresampled( $last, $new, 0, 0, ($nw / 2) – (200 / 2), ($nh / 2) – (200 / 2), 200, 200, 200, 200 ); // if i fits i sits. imagepng($last,$filename); imagedestroy($new); imagedestroy($last); 

Thumbnailing Images - Imagick $img = new Imagick($filename); $img->thumbnailImage(200,200); $img->writeImage($filename); $img->destroy(); 

Basic ‘Shoopin Shoop da woop  Desaturation  Sepia  Lots of other filters, but they are all more or less repetitive.  Watermarking  GD  imagefilter  imagecopyresampled  Imagick  modulateImage  sepiaToneImage  compositeImage 

Filters Almost over 9,000 GD  Negative  Greyscale  Brightness  Contrast  Colorize  Edge  Emboss  Blur  Sketch  Pixelate Imagick  Blur  3 Different Kinds  Brightness  Charcoal  Combine  Colorize  Color Replace  Distort  Enhance  Equalize  Flop  Frame  Gamma  Hue Shift  Level  Magnify  Median Filter  Modulate  Normalize  Oil Paint  Posturize  Rolling  Round corners  Sepia  Shade  Sharpen  Solarize  Stegano  Swirl  Texturize  Vignette 

Desaturate Images Black and white photographs GD $img = imagefrompng($filename); imagefilter( $img, IMG_FILTER_GRAYSCALE ); imagepng($img,$filename); imagedestroy($img); Imagick $img = new Imagick($filename); $img->modulateImage(100,0,100); $img->writeImage($filename); $img->destroy($filename); 

Sepia Tone Images Old photo aged photograph GD $img = imagefrompng($filename); imagefilter( $img, IMG_FILTER_GRAYSCALE ); imagefilter( $img, IMG_FILTER_COLORIZE, 90, 40, 3 ); imagepng($img,$filename); imagedestroy($img); Imagick $img = new Imagick($filename); $img->sepiaToneImage(80); $img->writeImage($filename); $img->destroy(); 

Watermarking Overlaying a ghost image on an image. GD $img = imagefrompng($filename); $mark = imagefrompng($watermarkfile); list($iw,$ih) = array(imagesx($img),imagesy($img)); list($mw,$mh) = array(imagesx($mark),imagesy($mark)); imagefilter( $mark, IMG_FILTER_GRAYSCALE ); imagecopyresampled( $img, $mark, ($iw - $mw), ($ih - $mh), 0, 0, $mw, $mh, $mw, $mh ); imagepng($img,$filename); imagedestroy($img); imagedestroy($mark); Imagick $img = new Imagick($filename); $mark = new Imagick($watermarkfile); $x = $img->getImageWidth()–$mark->getImageWidth(); $y = $img->getImageHeight()-$mark->getImageHeight(); $mark->modulateImage(100,0,100); $img->compositeImage( $mark, Imagick::COMPOSITE_DEFAULT, $x, $y ); $img->writeImage($filename); $img->destroy(); $mark->destroy(); 

Drawing Shapes and Text 

How they handle drawing. GD  Draw directly on to the image resource you want to draw on.  Fast.  Super easy if you do not need anything too involved. Imagick  Draw on a special “draw layer” and then lay it on top of the image.  Great for advanced drawing. Not as easy. 

Drawing Shapes Drawing an ellipse over the entire image. GD $img = imagefrompng($filename); $w = imagesx($img); $h = imagesy($img); $red = imagecolorallocate($img,255,0,0); // diametre based imagefilledellipse( $img, floor($w/2), floor($h/2), $w, $h, $red ); imagepng($img,$filename); imagedestroy($img); Imagick $img = new Imagick($filename); $w = $img->getImageWidth(); $h = $img->getImageHeight(); $draw = new ImagickDraw; $draw->setFillColor(new ImagickPixel(‘red’)); // radius based $draw->ellipse( floor($w/2), floor($h/2), floor($w/2), floor($h/2), 0, 360 ); $img->drawImage($draw); $img->writeImage($filename); $img->destroy(); $draw->destroy(); 

Writing Text on an Image Fonts are tricksy  Both Imagick and GD are suppose to have the ability to use the fonts installed on the system.  Except that works 0 times out of 10.  What does work? Absolute path to a font (TTF) file. That always works, in both libraries.  Font sizes: GD Points, Imagick Pixels. Derp.  PHP manual says Imagick is points too, but my own observations + other people say it is wrong. 

Writing Text on an Image – GD Apply directly to the forehead. GD $img = imagefrompng($filename); $color = imagecolorallocate($img,255,0,0); imagettftext( $img, $size, $angle, $x, $y, $color, $fontfile, $text ); imagepng($img,$filename); imagedestroy($img); 

Writing Text on an Image – Imagick Sort of works like an old typewriter. Really. Imagick $img = new Imagick($filename); $color = new ImagickPixel(‘red’); $draw = new ImagickDraw; $draw->setFont($fontfile); $draw->setFontSize($size); $draw->setFillColor($color); $img->annotateImage( $draw, $x, $y, $angle, $text ); $img->writeImage($filename); imagedestroy($img); 

Performance Speed and RAM use 

So, You’re punching pixels in the face? Image processing is slow (relative to, say, a PING).  Try to avoid doing large image processing during a request, if possible.  Something goofy like cropping a user avatar? That’s something that is OK to do live.  Leaving the webserver and request hanging to render a 8 megapixel subway map is not.  How and when you process is something you have to think about how your app works. 

Still pixel punching? I know, those little guys never give up. Punch harder.  The larger your images are, the more RAM you will need to allow PHP to use.  memory_limit=300M  You are probably looking at a value around this if your users are uploading photos off their new smarty telephones for you to scale down to web size.  memory_limit=2G  And this is what you are looking at if you are going to try stuff like this... 

Doing something HUGE because I can Daniel said I was crazy. Daniel doesn’t even know. I can see you Daniel. 15306x7653 pixel map of the earth. 3650 long/lat points to plot. GD  3.5sec to open  3.3sec to desaturate  0.05sec to plot  6sec to write JPEG to disk. 11.1MB  74sec to write PNG to disk. 46.1MB.  Peak RAM use: 1,043 MB Imagick  3sec  1.5sec to desaturate  1sec to plot  0.4sec plot “done right”  4.5sec to write JPEG to disk. 9.4MB  30sec to write PNG to disk. 46.3MB  Peak RAM use: 450 MB 

Performance Summary  Small images, lots of drawing? GD.  Small images, lots of filtering? Imagick.  Large images, doing anything? Ehh eh. Well. Imagick would probably be your best bet to try first.  Imagick if you value your alpha channel. 

Metadata EXIF in JPEGs, at least. 

Reading Metadata (EXIF)  Imagick is the only one of the two with the ability to read the tags. $img = new Imagick($filename); $exif = $img->getImageProperties(‘exif:*’);  GD, Imagick, nor EXIF can actually write EXIF data back to the image.  Imagick has this: $img->setImageProperty(‘exif:Model’,’iPwn Furr’);  But it does not actually write the modified data to disk... a known issue in the actual ImageMagick library itself that they don’t really care about. Sadface.  Someone solved this with PEL: https://github.com/lsolesen/pel  A set of classes for manipulating EXIF data on images. 

Reading Metadata (EXIF) (Cont...)  Crazy API... but it works... require('PelJpeg.php'); $jpg = new PelJpeg('image.jpg'); $entry = $jpg->getExif()->getTiff()->getIfd()->getEntry(PelTag::MODEL); echo $entry->getValue, PHP_EOL; // outputs ‘iPhone 4’ on a photo from my phone. $entry->setValue('iPwn Furr'); $jpg->saveFile('image.jpg');  Important to note, this example here has no error checking. At any point those methods could have returned null and exploded the entire chain.  Opinion: We need a different kind of crazy person to go in and actually make that usable, unless there is a convenience class I completely missed because the documentation didn’t mention it.  e.g. I had to learn way more about the JPEG/EXIF binary format than I should have to set meta data with this. 

Metadata Alternatives  Things you could shell_exec...  Exiftool  Jhead  Just make sure you know how to escapeshellargs. 

The End Twitter: @bobmajdakjr Email: [email protected] Blog: http://catch404.net This entire codebase (demo site, apps, libraries) on Github. https://github.com/bobmajdak jr/dallasphp-image-tools- code