diff --git a/src/Grafika/EditorInterface.php b/src/Grafika/EditorInterface.php
index e240942..8be7ac5 100644
--- a/src/Grafika/EditorInterface.php
+++ b/src/Grafika/EditorInterface.php
@@ -30,7 +30,7 @@ public function apply( &$image, $filter );
      *
      * @return EditorInterface An instance of Editor.
      */
-    public function blend(&$image1, $image2, $type='normal', $opacity = 1.0, $position = 'top-left', $offsetX = 0, $offsetY = 0 );
+    public function blend(ImageInterface &$image1, ImageInterface $image2, $type = 'normal', float $opacity = 1.0, string $position = 'top-left', int $offsetX = 0, int $offsetY = 0);
 
     /**
      * Compare two images and returns a hamming distance. A value of 0 indicates a likely similar picture. A value between 1 and 10 is potentially a variation. A value greater than 10 is likely a different image.
@@ -252,4 +252,4 @@ public function save( $image, $file, $type = null, $quality = null, $interlace =
      */
     public function text( &$image, $text, $size = 12, $x = 0, $y = 12, $color = null, $font = '', $angle = 0 );
 
-}
\ No newline at end of file
+}
diff --git a/src/Grafika/Gd/Editor.php b/src/Grafika/Gd/Editor.php
index 1fb29a5..808bcbc 100644
--- a/src/Grafika/Gd/Editor.php
+++ b/src/Grafika/Gd/Editor.php
@@ -54,7 +54,7 @@ public function apply( &$image, $filter)
      * @return Editor
      * @throws \Exception When added image is outside of canvas or invalid blend type
      */
-    public function blend(&$image1, $image2, $type='normal', $opacity = 1.0, $position = 'top-left', $offsetX = 0, $offsetY = 0 ){
+    public function blend(ImageInterface &$image1, ImageInterface $image2, $type='normal', float $opacity = 1.0, string $position = 'top-left', int $offsetX = 0, int $offsetY = 0) {
 
         // Turn into position object
         $position = new Position($position, $offsetX, $offsetY);
@@ -113,7 +113,7 @@ public function blend(&$image1, $image2, $type='normal', $opacity = 1.0, $positi
 
         $type = strtolower( $type );
         if($type==='normal') {
-            if ( $opacity !== 1 ) {
+            if ( $opacity !== 1.0 ) {
                 $this->opacity($image2, $opacity);
             }
             imagecopy( $canvas, $gd2, $loopStartX + $offsetX, $loopStartY + $offsetY, 0, 0, $image2->getWidth(), $image2->getHeight());
@@ -1176,4 +1176,4 @@ private function _smartCrop($oldImage, $cropW, $cropH){
 
         return array($x,$y);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Grafika/Imagick/Editor.php b/src/Grafika/Imagick/Editor.php
index 36d698f..d65052d 100644
--- a/src/Grafika/Imagick/Editor.php
+++ b/src/Grafika/Imagick/Editor.php
@@ -53,8 +53,8 @@ public function apply(&$image, $filter)
      * @return Editor
      * @throws \Exception When added image is outside of canvas or invalid blend type
      */
-    public function blend(&$image1, $image2, $type='normal', $opacity = 1.0, $position = 'top-left', $offsetX = 0, $offsetY = 0 ){
-
+    public function blend(ImageInterface &$image1, ImageInterface $image2, $type = 'normal', float $opacity = 1.0, string $position = 'top-left', int $offsetX = 0, int $offsetY = 0)
+    {
         // Turn into position object
         $position = new Position($position, $offsetX, $offsetY);
 
@@ -86,7 +86,7 @@ public function blend(&$image1, $image2, $type='normal', $opacity = 1.0, $positi
             $loopStartY += $diff;
         }
 
-        if ( $opacity !== 1 ) {
+        if ( $opacity !== 1.0 ) {
             $this->opacity($image2, $opacity);
         }
 
@@ -824,4 +824,4 @@ private function _getImageTypeFromFileName($imageFile)
         }
     }
 
-}
\ No newline at end of file
+}