diff --git a/imagemagick.api.php b/imagemagick.api.php
index b05fafe..cc0f9f2 100644
--- a/imagemagick.api.php
+++ b/imagemagick.api.php
@@ -2,6 +2,52 @@
 
 /**
  * @file
- * API documentation for ImageMagick module.
+ * API documentation for the ImageMagick module.
  */
 
+/**
+ * Alter an image as it is loaded by the ImageMagick toolkit.
+ *
+ * @param $image
+ *   An image object.
+ *
+ * @ingroup hooks
+ */
+function hook_imagemagick_load_alter(stdClass $image) {
+}
+
+/**
+ * Alter an image before it is saved by the ImageMagick toolkit.
+ *
+ * @param $image
+ *   An image object.
+ * @param $context
+ *   An associative array of information about the image being saved.
+ *   - destination: A string file URI where the image will be saved.
+ *
+ * @ingroup hooks
+ */
+function hook_imagemagick_save_alter(stdClass $image, $context = array()) {
+}
+
+/**
+ * Alter the arguments to the ImageMagick 'convert' command-line program.
+ *
+ * @param $args
+ *   An array of arguments to the ImageMagick 'convert' command-line program.
+ * @param $context
+ *   An associative array of information about the image being altered.
+ *   - source: A string filesystem path of the original image.
+ *   - source_original: A string file URI of the original image.
+ *   - destination: A string filesystem path of the derivative image.
+ *   - destination_original: A string file URI of the derivative image.
+ *   - destination_format: A string format of the derivative image.
+ *
+ * @see http://www.imagemagick.org/script/convert.php
+ * @see http://www.imagemagick.org/script/command-line-processing.php#output
+ * @see http://www.imagemagick.org/Usage/files/#save
+ *
+ * @ingroup hooks
+ */
+function hook_imagemagick_arguments_alter($args, $context = array()) {
+}
diff --git a/imagemagick.module b/imagemagick.module
index c42f3b4..81e1bd5 100644
--- a/imagemagick.module
+++ b/imagemagick.module
@@ -359,28 +359,41 @@ function image_imagemagick_get_info(stdClass $image) {
 /**
  * Calls the convert executable with the specified filter.
  */
-function _imagemagick_convert($source, $dest, $args) {
+function _imagemagick_convert($source, $destination, $args) {
+  // Backup original paths for alter hook context.
+  $source_original = $source;
+  $destination_original = $destination;
   $source = drupal_realpath($source);
-  $dest = drupal_realpath($dest);
+  $destination = drupal_realpath($destination);
+  $destination_format = '';
 
   $args['quality'] = '-quality ' . escapeshellarg(variable_get('imagemagick_quality', 75));
 
   // Allow other modules to alter the ImageMagick command line parameters.
   $context = array(
-    'source' => $source,
-    'destination' => $dest,
+    'source' => &$source,
+    'source_original' => $source_original,
+    'destination' => &$destination,
+    'destination_original' => $destination_original,
+    'destination_format' => &$destination_format,
   );
   drupal_alter('imagemagick_arguments', $args, $context);
 
+  // If the format of the derivative image is being changed, append the
+  // the destination path to the new image format.
+  if (is_string($destination_format) && $destination_format != '') {
+    $destination_format .=  ':' . $destination;
+  }
+
   // To make use of ImageMagick 6's parenthetical command grouping we need to make
   // the $source image the first parameter and $dest the last.
   // @see http://www.imagemagick.org/Usage/basics/#cmdline
-  $command = escapeshellarg($source) . ' ' . implode(' ', $args) . ' ' . escapeshellarg($dest);
+  $command = escapeshellarg($source) . ' ' . implode(' ', $args) . ' ' . escapeshellarg($destination_format ? $destination_format : $destination);
 
   if (_imagemagick_convert_exec($command, $output, $error) !== TRUE) {
     return FALSE;
   }
-  return file_exists($dest);
+  return file_exists($destination);
 }
 
 /**
@@ -492,4 +505,3 @@ function _imagemagick_convert_exec($command_args, &$output = NULL, &$error = NUL
 /**
  * @} End of "ingroup image".
  */
-