diff --git a/system/assets/responsive-overlays/1x.png b/system/assets/responsive-overlays/1x.png
new file mode 100644
index 000000000..1e3573fe3
Binary files /dev/null and b/system/assets/responsive-overlays/1x.png differ
diff --git a/system/assets/responsive-overlays/2x.png b/system/assets/responsive-overlays/2x.png
new file mode 100644
index 000000000..501b5b830
Binary files /dev/null and b/system/assets/responsive-overlays/2x.png differ
diff --git a/system/assets/responsive-overlays/3x.png b/system/assets/responsive-overlays/3x.png
new file mode 100644
index 000000000..8052b0940
Binary files /dev/null and b/system/assets/responsive-overlays/3x.png differ
diff --git a/system/assets/responsive-overlays/4x.png b/system/assets/responsive-overlays/4x.png
new file mode 100644
index 000000000..2676a1348
Binary files /dev/null and b/system/assets/responsive-overlays/4x.png differ
diff --git a/system/assets/responsive-overlays/unknown.png b/system/assets/responsive-overlays/unknown.png
new file mode 100644
index 000000000..09df3a748
Binary files /dev/null and b/system/assets/responsive-overlays/unknown.png differ
diff --git a/system/config/system.yaml b/system/config/system.yaml
index a7c1ada23..a3ac7e7a4 100644
--- a/system/config/system.yaml
+++ b/system/config/system.yaml
@@ -63,3 +63,6 @@ debugger:
   twig: true                           # Enable debugging of Twig templates
   shutdown:
     close_connection: true             # Close the connection before calling onShutdown(). false for debugging
+
+images:
+  debug: false                         # Show an overlay over images indicating the pixel depth of the image when working with retina for example
diff --git a/system/src/Grav/Common/Markdown/ParsedownGravTrait.php b/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
index ea2f5abf9..9ba39e423 100644
--- a/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
+++ b/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
@@ -104,6 +104,7 @@ trait ParsedownGravTrait
 
             //get the url and parse it
             $url = parse_url(htmlspecialchars_decode($excerpt['element']['attributes']['src']));
+
             $path_parts = pathinfo($url['path']);
 
             // if there is no host set but there is a path, the file is local
@@ -145,27 +146,42 @@ trait ParsedownGravTrait
                         }
                     }
 
-                    // Get the URL for regular images, or an array of bits needed to put together
-                    // the lightbox HTML
-                    if (!isset($actions['lightbox'])) {
-                        $src = $medium->url();
-                    } else {
-                        $src = $medium->lightboxRaw();
-                    }
+                    $data = $medium->htmlRaw();
 
                     // set the src element with the new generated url
-                    if (!isset($actions['lightbox']) && !is_array($src)) {
-                        $excerpt['element']['attributes']['src'] = $src;
+                    if (!isset($actions['lightbox'])) {
+                        $excerpt['element']['attributes']['src'] = $data['img_src'];
+
+                        if ($data['img_srcset']) {
+                            $excerpt['element']['attributes']['srcset'] = $data['img_srcset'];;
+                            $excerpt['element']['attributes']['sizes'] = '100vw';
+                        }
+
                     } else {
                         // Create the custom lightbox element
+                        
+                        $attributes = $data['a_attributes'];
+                        $attributes['href'] = $data['a_href'];
+
+                        $img_attributes = [
+                            'src' => $data['img_src'],
+                            'alt' => $alt,
+                            'title' => $title
+                        ];
+
+                        if ($data['img_srcset']) {
+                            $img_attributes['srcset'] = $data['img_srcset'];
+                            $img_attributes['sizes'] = '100vw';
+                        }
+
                         $element = array(
                             'name' => 'a',
-                            'attributes' => array('rel' => $src['a_rel'], 'href' => $src['a_url']),
+                            'attributes' => $attributes,
                             'handler' => 'element',
                             'text' => array(
                                 'name' => 'img',
-                                'attributes' => array('src' => $src['img_url'], 'alt' => $alt, 'title' => $title)
-                            ),
+                                'attributes' => $img_attributes
+                            )
                         );
 
                         // Set any custom classes on the lightbox element
diff --git a/system/src/Grav/Common/Page/Media.php b/system/src/Grav/Common/Page/Media.php
index 97ac69962..ae5defa44 100644
--- a/system/src/Grav/Common/Page/Media.php
+++ b/system/src/Grav/Common/Page/Media.php
@@ -49,77 +49,81 @@ class Media extends Getters
 
             // Find out the real filename, in case of we are at the metadata.
             $filename = $info->getFilename();
-            list($basename, $ext, $meta) = $this->getFileParts($filename);
+            list($basename, $ext, $meta, $alternative) = $this->getFileParts($filename);
 
-            // Get medium instance creating it if it didn't exist.
-            $medium = $this->get("{$basename}.{$ext}", true);
-            if (!$medium) {
+            // Get medium instance if it already exists.
+            $medium = $this->get("{$basename}.{$ext}");
+
+            if (!$alternative) {
+                
+                $medium = $medium ? $medium : $this->createMedium($info->getPathname());
+
+                if (!$medium) {
+                    continue;
+                }
+
+                if ($meta) {
+                    $medium->addMetaFile($meta);
+                } else {
+                    $medium->set('size', $info->getSize());
+                }
+            } else {
+
+                $altMedium = $this->createMedium($info->getPathname());
+                
+                if (!$altMedium) {
+                    continue;
+                }
+
+                $altMedium->set('size', $info->getSize());
+
+                if (!$medium) {
+                    $medium = $this->createMedium("{$path}/${basename}.${ext}");
+
+                    if ($medium) {
+                        $medium->set('size', filesize("{$path}/${basename}.${ext}"));
+                    }
+                }
+
+                $medium = $medium ? $medium : $this->scaleMedium($altMedium, $alternative, 1);
+                
+                $medium->addAlternative($this->parseRatio($alternative), $altMedium);
+            }
+
+            $this->add("{$basename}.{$ext}", $medium);
+        }
+
+        foreach ($this->images() as $medium) {
+
+            $alternatives = $medium->getAlternatives();
+
+            if (empty($alternatives)) {
                 continue;
             }
 
-            //set file size
-            $medium->set('size', $info->getSize());
+            $max = max(array_keys($alternatives));
 
-            // Assign meta files to the medium.
-            if ($meta) {
-                $medium->addMetaFile($meta);
+            for ($i=2; $i < $max; $i++) {
+
+                if (isset($alternatives[$i])) {
+                    continue;
+                }
+
+                $medium->addAlternative($i, $this->scaleMedium($alternatives[$max], $max, $i));
             }
         }
     }
 
+
+
     /**
-     * Get medium by basename and extension.
+     * Get medium by filename.
      *
      * @param string $filename
-     * @param bool   $create
      * @return Medium|null
      */
-    public function get($filename, $create = false)
+    public function get($filename)
     {
-        if ($create && !isset($this->instances[$filename])) {
-            $parts = explode('.', $filename);
-            $ext = array_pop($parts);
-            $basename = implode('.', $parts);
-
-            /** @var Config $config */
-            $config = self::$grav['config'];
-
-            // Check if medium type has been configured.
-            $params = $config->get("media.".strtolower($ext));
-            if (!$params) {
-                return null;
-            }
-
-            $filePath = $this->path . '/' . $filename;
-
-            // Add default settings for undefined variables.
-            $params += $config->get('media.defaults');
-            $params += array(
-                'type' => 'file',
-                'thumb' => 'media/thumb.png',
-                'mime' => 'application/octet-stream',
-                'name' => $filename,
-                'filename' => $filename,
-                'basename' => $basename,
-                'extension' => $ext,
-                'path' => $this->path,
-                'modified' => filemtime($filePath),
-            );
-
-            $lookup = array(
-                USER_DIR . 'images/',
-                SYSTEM_DIR . 'images/',
-            );
-            foreach ($lookup as $path) {
-                if (is_file($path . $params['thumb'])) {
-                    $params['thumb'] = $path . $params['thumb'];
-                    break;
-                }
-            }
-
-            $this->add(new Medium($params));
-        }
-
         return isset($this->instances[$filename]) ? $this->instances[$filename] : null;
     }
 
@@ -178,24 +182,113 @@ class Media extends Getters
         return $this->files;
     }
 
+    /**
+     * Create a Medium object from a file
+     *
+     * @param string $file
+     * 
+     * @return Medium|null
+     */
+    protected function createMedium($file)
+    {
+        if (!file_exists($file)) {
+            return null;
+        }
+
+        $path = dirname($file);
+        $filename = basename($file);
+        $parts = explode('.', $filename);
+        $ext = array_pop($parts);
+        $basename = implode('.', $parts);
+
+        /** @var Config $config */
+        $config = self::$grav['config'];
+
+        // Check if medium type has been configured.
+        $params = $config->get("media.".strtolower($ext));
+        if (!$params) {
+            return null;
+        }
+
+        // Add default settings for undefined variables.
+        $params += $config->get('media.defaults');
+        $params += array(
+            'type' => 'file',
+            'thumb' => 'media/thumb.png',
+            'mime' => 'application/octet-stream',
+            'name' => $filename,
+            'filename' => $filename,
+            'basename' => $basename,
+            'extension' => $ext,
+            'path' => $path,
+            'modified' => filemtime($file),
+        );
+
+        $lookup = array(
+            USER_DIR . 'images/',
+            SYSTEM_DIR . 'images/',
+        );
+        foreach ($lookup as $lookupPath) {
+            if (is_file($lookupPath . $params['thumb'])) {
+                $params['thumb'] = $lookupPath . $params['thumb'];
+                break;
+            }
+        }
+
+        return new Medium($params);
+    }
+
+    protected function scaleMedium($medium, $from, $to)
+    {
+        $from = $this->parseRatio($from);
+        $to = $this->parseRatio($to);
+
+        if ($to > $from) {
+            return $medium;
+        }
+
+        $ratio = $to / $from;
+        $width = (int) ($medium->get('width') * $ratio);
+        $height = (int) ($medium->get('height') * $ratio);
+
+        $basename = $medium->get('basename');
+        $basename = str_replace('@'.$from.'x', '@'.$to.'x', $basename);
+
+        $debug = $medium->get('debug');
+        $medium->set('debug', false);
+
+        $file = $medium->resize($width, $height)->setPrettyName($basename)->url();
+        $file = preg_replace('|'. preg_quote(self::$grav['base_url_relative']) .'$|', '', GRAV_ROOT) . $file;
+
+        $medium->set('debug', $debug);
+
+        $size = filesize($file);
+
+        $medium = $this->createMedium($file);
+        $medium->set('size', $size);
+
+        return $medium;
+    }
+
+
     /**
      * @internal
      */
-    protected function add($file)
+    protected function add($name, $file)
     {
-        $this->instances[$file->filename] = $file;
+        $this->instances[$name] = $file;
         switch ($file->type) {
             case 'image':
-                $this->images[$file->filename] = $file;
+                $this->images[$name] = $file;
                 break;
             case 'video':
-                $this->videos[$file->filename] = $file;
+                $this->videos[$name] = $file;
                 break;
             case 'audio':
-                $this->audios[$file->filename] = $file;
+                $this->audios[$name] = $file;
                 break;
             default:
-                $this->files[$file->filename] = $file;
+                $this->files[$name] = $file;
         }
     }
 
@@ -210,6 +303,13 @@ class Media extends Getters
         $fileParts = explode('.', $filename);
 
         $name = array_shift($fileParts);
+        $alternative = false;
+
+        if (preg_match('/(.*)@(\d+x)$/', $name, $matches)) {
+            $name = $matches[1];
+            $alternative = $matches[2];
+        }
+
         $extension = null;
         while (($part = array_shift($fileParts)) !== null) {
             if ($part != 'meta') {
@@ -223,6 +323,15 @@ class Media extends Getters
         }
         $meta = implode('.', $fileParts);
 
-        return array($name, $extension, $meta);
+        return array($name, $extension, $meta, $alternative);
+    }
+
+    protected function parseRatio($ratio)
+    {
+        if (!is_numeric($ratio)) {
+            $ratio = (float) trim($ratio, 'x');
+        }
+
+        return $ratio;
     }
 }
diff --git a/system/src/Grav/Common/Page/Medium.php b/system/src/Grav/Common/Page/Medium.php
index b963b0906..66d4c7b90 100644
--- a/system/src/Grav/Common/Page/Medium.php
+++ b/system/src/Grav/Common/Page/Medium.php
@@ -49,24 +49,49 @@ class Medium extends Data
 
     protected $type = 'guess';
     protected $quality = 85;
+    protected $debug_watermarked = false;
 
-    public static $valid_actions = ['resize', 'forceResize', 'cropResize', 'crop', 'cropZoom',
+    public static $valid_actions = [
+        // Medium functions
+        'format', 'lightbox', 'link', 'reset',
+        
+        // Gregwar Image functions
+        'resize', 'forceResize', 'cropResize', 'crop', 'cropZoom',
         'negate', 'brightness', 'contrast', 'grayscale', 'emboss', 'smooth', 'sharp', 'edge', 'colorize', 'sepia' ];
 
+    public static $size_param_actions = [
+        'resize' => [ 0, 1 ],
+        'forceResize' => [ 0, 1 ],
+        'cropResize' => [ 0, 1 ],
+        'crop' => [ 0, 1, 2, 3 ],
+        'cropResize' => [ 0, 1 ],
+        'zoomCrop' => [ 0, 1 ]
+    ];
+
     /**
      * @var array
      */
     protected $meta = array();
 
     /**
-     * @var string
+     * @var array
      */
-    protected $linkTarget;
+    protected $alternatives = array();
 
     /**
      * @var string
      */
-    protected $linkAttributes;
+    protected $linkTarget;
+
+        /**
+     * @var string
+     */
+    protected $linkSrcset;
+
+    /**
+     * @var string
+     */
+    protected $linkAttributes = [];
 
     public function __construct($items = array(), Blueprint $blueprint = null)
     {
@@ -89,7 +114,7 @@ class Medium extends Data
             $this->def('mime', 'application/octet-stream');
         }
 
-
+        $this->set('debug', self::$grav['config']->get('system.images.debug')); 
     }
 
     /**
@@ -113,7 +138,7 @@ class Medium extends Data
         $config = self::$grav['config'];
 
         if ($this->image) {
-            $output = $this->image->cacheFile($this->type, $this->quality);
+            $output = $this->saveImage();
             $this->reset();
             $output = ROOT_DIR . $output;
         } else {
@@ -122,6 +147,128 @@ class Medium extends Data
         return $output;
     }
 
+    /**
+     * Return URL to file.
+     *
+     * @return string
+     */
+    public function url($reset = true)
+    {
+        if ($this->image) {
+            $output = $this->saveImage();
+            
+            if ($reset) $this->reset();
+        } else {
+            $relPath = preg_replace('|^' . ROOT_DIR . '|', '', $this->get('path'));
+            $output = $relPath . '/' . $this->get('filename');
+        }
+
+        return self::$grav['base_url'] . '/'. $output;
+    }
+    
+
+    /**
+     * Return srcset string for this Medium and its alternatives
+     * 
+     * @return string
+     */
+    public function srcset($reset = true)
+    {
+        if (empty($this->alternatives)) {
+            if ($reset) $this->reset();
+            return '';
+        }
+
+        $srcset = [ $this->url($reset) . ' ' . $this->get('width') . 'w' ];
+
+        foreach ($this->alternatives as $ratio => $medium) {
+            $srcset[] = $medium->url($reset) . ' ' . $medium->get('width') . 'w';
+        }
+        
+        return implode(', ', $srcset);
+    }
+
+    /**
+     * Returns <img> tag from the medium.
+     *
+     * @param string $title
+     * @param string $class
+     * @param string $type
+     * @param int $quality
+     * @return string
+     */
+    public function img($title = null, $class = null, $type = null, $quality = 80, $reset = true)
+    {
+        if (!$this->image) {
+            $this->image();
+        }
+
+        $output = $this->html($title, $class, $type, $quality, $reset);
+
+        return $output;
+    }
+
+    /**
+     * Return HTML markup from the medium.
+     *
+     * @param string $title
+     * @param string $class
+     * @param string $type
+     * @param int $quality
+     * @return string
+     */
+    public function html($title = null, $class = null, $reset = true)
+    {
+        $data = $this->htmlRaw($reset);
+
+        $title = $title ? $title : $this->get('title');
+        $class = $class ? $class : '';
+
+        if ($this->image) {
+            $attributes = $data['img_srcset'] ? ' srcset="' . $data['img_srcset'] . '" sizes="100vw"' : '';
+            $output = '<img src="' . $data['img_src'] . '"' . $attributes . ' class="'. $class . '" alt="' . $title . '" />';
+        } else {
+            $output = $data['text'];
+        }
+
+        if (isset($data['a_href'])) {
+
+            $attributes = '';
+            foreach ($data['a_attributes'] as $prop => $value) {
+                $attributes .= " {$prop}=\"{$value}\"";
+            }
+
+            $output = '<a href="' . $data['a_href'] . '"' . $attributes . ' class="'. $class . '">' . $output . '</a>';
+        }
+
+        return $output;
+    }
+
+    public function htmlRaw($reset = true)
+    {
+        $output = [];
+
+        if ($this->image) {
+            $output['img_src'] = $this->url(false);
+            $output['img_srcset'] = $this->srcset($reset);
+        } else {
+            $output['text'] = $title;
+        }
+
+        if ($this->linkTarget) {
+            /** @var Config $config */
+            $config = self::$grav['config'];
+
+            $output['a_href'] = $this->linkTarget;
+            $output['a_attributes'] = $this->linkAttributes;
+            
+            $this->linkTarget = null;
+            $this->linkAttributes = [];
+        }
+
+        return $output;
+    }
+
     /**
      * Sets the quality of the image
      * @param  Int $quality 0-100 quality
@@ -133,24 +280,6 @@ class Medium extends Data
         return $this;
     }
 
-    /**
-     * Return URL to file.
-     *
-     * @return string
-     */
-    public function url()
-    {
-        if ($this->image) {
-            $output = $this->image->cacheFile($this->type, $this->quality);
-            $this->reset();
-        } else {
-            $relPath = preg_replace('|^' . ROOT_DIR . '|', '', $this->get('path'));
-            $output = $relPath . '/' . $this->get('filename');
-        }
-
-        return self::$grav['base_url'] . '/'. $output;
-    }
-
     /**
      * Sets image output format.
      *
@@ -170,91 +299,7 @@ class Medium extends Data
     }
 
     /**
-     * Returns <img> tag from the medium.
-     *
-     * @param string $title
-     * @param string $class
-     * @param string $type
-     * @param int $quality
-     * @return string
-     */
-    public function img($title = null, $class = null, $type = null, $quality = 80)
-    {
-        if (!$this->image) {
-            $this->image();
-        }
-
-        $output = $this->html($title, $class, $type, $quality);
-
-        return $output;
-    }
-
-    /**
-     * Return HTML markup from the medium.
-     *
-     * @param string $title
-     * @param string $class
-     * @param string $type
-     * @param int $quality
-     * @return string
-     */
-    public function html($title = null, $class = null, $type = null, $quality = 80)
-    {
-        $title = $title ? $title : $this->get('title');
-        $class = $class ? $class : '';
-
-        if ($this->image) {
-            $type = $type ? $type : $this->type;
-            $quality = $quality ? $quality : $this->quality;
-
-            $url = $this->url($type, $quality);
-            $this->reset();
-
-            $output = '<img src="' . $url . '" class="'. $class . '" alt="' . $title . '" />';
-        } else {
-            $output = $title;
-        }
-
-        if ($this->linkTarget) {
-            /** @var Config $config */
-            $config = self::$grav['config'];
-
-            $output = '<a href="' . self::$grav['base_url'] . '/'. $this->linkTarget
-                . '"' . $this->linkAttributes. ' class="'. $class . '">' . $output . '</a>';
-
-            $this->linkTarget = $this->linkAttributes = null;
-        }
-
-        return $output;
-    }
-
-    /**
-     * Return lightbox HTML for the medium.
-     *
-     * @param int $width
-     * @param int $height
-     * @return $this
-     */
-    public function lightbox($width = null, $height = null)
-    {
-        $this->linkAttributes = ' rel="lightbox"';
-
-        return $this->link($width, $height);
-    }
-
-    public function lightboxRaw($width = null, $height = null)
-    {
-        /** @var Config $config */
-        $config = self::$grav['config'];
-        $url = $this->url();
-        $this->link($width, $height);
-        $lightbox_url = self::$grav['base_url'] . '/'. $this->linkTarget;
-
-        return array('a_url' => $lightbox_url, 'a_rel' => 'lightbox', 'img_url' => $url);
-    }
-
-    /**
-     * Return link HTML for the medium.
+     * Enable link for the medium object
      *
      * @param int $width
      * @param int $height
@@ -263,11 +308,12 @@ class Medium extends Data
     public function link($width = null, $height = null)
     {
         if ($this->image) {
-            $image = clone $this->image;
-            if ($width && $height) {
-                $image->cropResize($width, $height);
+            $this->linkTarget = $this->url(false);
+            $srcset = $this->srcset();
+
+            if ($srcset) {
+                $this->linkAttributes['data-srcset'] = $srcset;
             }
-            $this->linkTarget = $image->cacheFile($this->type, $this->quality);
         } else {
             // TODO: we need to find out URI in a bit better way.
             $relPath = preg_replace('|^' . ROOT_DIR . '|', '', $this->get('path'));
@@ -277,6 +323,20 @@ class Medium extends Data
         return $this;
     }
 
+    /**
+     * Enable lightbox for the medium.
+     *
+     * @param int $width
+     * @param int $height
+     * @return $this
+     */
+    public function lightbox($width = null, $height = null)
+    {
+        $this->linkAttributes['rel'] = 'lightbox';
+
+        return $this->link($width, $height);
+    }
+
     /**
      * Reset image.
      *
@@ -292,6 +352,7 @@ class Medium extends Data
         }
         $this->type = 'guess';
         $this->quality = 80;
+        $this->debug_watermarked = false;
 
         return $this;
     }
@@ -316,6 +377,20 @@ class Medium extends Data
 
         try {
             $result = call_user_func_array(array($this->image, $method), $args);
+
+            foreach ($this->alternatives as $ratio => $medium) {
+
+                $args_copy = $args;
+
+                if (isset(self::$size_param_actions[$method])) {
+                    foreach (self::$size_param_actions[$method] as $param) {
+                        if (isset($args_copy[$param]))
+                            $args_copy[$param] = (int) $args_copy[$param] * $ratio;
+                    }
+                }
+
+                call_user_func_array(array($medium, $method), $args_copy);
+            }
         } catch (\BadFunctionCallException $e) {
             $result = null;
         }
@@ -344,6 +419,28 @@ class Medium extends Data
         return $this;
     }
 
+    protected function saveImage()
+    {
+        if (!$this->image) {
+            $this->image();
+        }
+
+        if ($this->get('debug') && !$this->debug_watermarked) {
+
+            $ratio = $this->get('ratio');
+            if (!$ratio) {
+                $ratio = 1;
+            }
+
+            $overlay = SYSTEM_DIR . '/assets/responsive-overlays/' . $ratio . 'x.png';
+            $overlay = file_exists($overlay) ? $overlay : SYSTEM_DIR . '/assets/responsive-overlays/unknown.png';
+
+            $this->image->merge(ImageFile::open($overlay));
+        }
+
+        return $this->image->cacheFile($this->type, $this->quality);
+    }
+
     /**
      * Add meta file for the medium.
      *
@@ -365,6 +462,29 @@ class Medium extends Data
         return $this;
     }
 
+    /**
+     * Add alternative Medium to this Medium
+     *
+     * @param $type
+     * @param $alternative
+     * @return $this
+     */
+    public function addAlternative($ratio, Medium $alternative)
+    {
+        if (!is_numeric($ratio) || $ratio === 0) {
+            return;
+        }
+
+        $alternative->set('ratio', $ratio);
+
+        $this->alternatives[(float) $ratio] = $alternative;
+    }
+
+    public function getAlternatives()
+    {
+        return $this->alternatives;
+    }
+
     /**
      * Filter image by using user defined filter parameters.
      *