diff -up im_raw.old/im_raw.module im_raw/im_raw.module
--- im_raw.old/im_raw.module	2012-04-18 00:19:06.653916606 +0400
+++ im_raw/im_raw.module	2012-04-18 00:22:50.271025470 +0400
@@ -43,6 +43,7 @@ function im_raw_image_effect_info() {
     'effect callback' => 'im_raw_effect',
     'form callback' => 'im_raw_form',
     'summary theme' => 'im_raw_summary',
+    'dimensions callback' => 'im_raw_scale_dimensions',
   );
 
   return $effects;
@@ -63,6 +64,33 @@ function im_raw_form($data) {
       '#resizable' => 'TRUE',
       '#required' => 'TRUE'
     );
+    $form['dimensions'] = array(
+      '#type' => 'fieldset',
+      '#title' => t('Dimensions'),
+      '#description' => t('Passthru dimensions of an image. Will be used as-is in HTML. Use it if know the exact WIDTH and HEIGHT of a resulting image after aplying the above effect.'),
+      '#collapsed' => FALSE,
+      '#collapsible' => TRUE,
+    );
+    $form['dimensions']['width'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Width'),
+      '#default_value' => isset($data['dimensions']['width']) ? $data['dimensions']['width'] : '',
+      '#field_suffix' => ' ' . t('pixels'),
+      '#required' => FALSE,
+      '#size' => 10,
+      '#element_validate' => array('image_effect_integer_validate'),
+      '#allow_negative' => FALSE,
+    );
+    $form['dimensions']['height'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Height'),
+      '#default_value' => isset($data['dimensions']['height']) ? $data['dimensions']['height'] : '',
+      '#field_suffix' => ' ' . t('pixels'),
+      '#required' => FALSE,
+      '#size' => 10,
+      '#element_validate' => array('image_effect_integer_validate'),
+      '#allow_negative' => FALSE,
+    );
   }
   else {
     $form['commandline'] = array(
@@ -93,6 +121,30 @@ function im_raw_effect(stdClass $image,
 }
 
 /**
+ * Image dimensions callback.
+ *
+ * @param $dimensions
+ *   Dimensions to be modified - an array with components width and height, in
+ *   pixels.
+ * @param $data
+ *   An array of attributes to use when performing the scale effect with the
+ *   following items:
+ *   - "commandline": The command line to pass to ImageMagick
+ *   - "width": An integer representing the desired width in pixels.
+ *   - "height": An integer representing the desired height in pixels.
+ */
+
+function im_raw_scale_dimensions(array &$dimensions, array $data) {
+  // We are not modifying anything actually
+  if ($data['dimensions']['width']) {
+    $dimensions['width'] = $data['dimensions']['width'];
+  }
+  if ($data['dimensions']['height']) {
+    $dimensions['height'] = $data['dimensions']['height'];
+  }
+}
+
+/**
  * clear image cache
  */
 function im_raw_enable() {