diff --git a/core/lib/Drupal/Core/Image/Image.php b/core/lib/Drupal/Core/Image/Image.php
index 4cbc63a..d1edb6e 100644
--- a/core/lib/Drupal/Core/Image/Image.php
+++ b/core/lib/Drupal/Core/Image/Image.php
@@ -57,15 +57,15 @@ class Image implements ImageInterface {
   /**
    * Constructs a new Image object.
    *
-   * @param string $source
-   *   The path to an image file, or an empty string to construct the object
-   *   with no image source.
    * @param \Drupal\Core\ImageToolkit\ImageToolkitInterface $toolkit
    *   The image toolkit.
+   * @param string|null $source
+   *   (optional) The path to an image file, or NULL to construct the object
+   *   with no image source.
    */
-  public function __construct($source, ImageToolkitInterface $toolkit) {
+  public function __construct(ImageToolkitInterface $toolkit, $source = NULL) {
     $this->toolkit = $toolkit;
-    if (!empty($source)) {
+    if ($source) {
       $this->source = $source;
       $this->processInfo();
     }
@@ -216,7 +216,7 @@ protected function processInfo() {
    * interface method ImageInterface::apply(). An image operation will be
    * performed as in the next example:
    * @code
-   * $image = new Image($path, $toolkit);
+   * $image = new Image($toolkit, $path);
    * $image->apply('scale', array('width' => 50, 'height' => 100));
    * @endcode
    * Also in https://drupal.org/node/2110499 operation arguments sent to toolkit
diff --git a/core/lib/Drupal/Core/Image/ImageFactory.php b/core/lib/Drupal/Core/Image/ImageFactory.php
index a909ff4..c7adf4c 100644
--- a/core/lib/Drupal/Core/Image/ImageFactory.php
+++ b/core/lib/Drupal/Core/Image/ImageFactory.php
@@ -74,19 +74,20 @@ public function getToolkitId() {
    * current factory settings, by passing its plugin ID in the $toolkit_id
    * argument.
    *
-   * @param string $source
-   *   The path to an image file, or an empty string to construct the object
+   * @param string|null $source
+   *   (optional) The path to an image file, or NULL to construct the object
    *   with no image source.
-   * @param string $toolkit_id
-   *   (Optional) The image toolkit ID to use for this image.
+   * @param string|null $toolkit_id
+   *   (optional) The ID of the image toolkit to use for this image, or NULL
+   *   to use the current toolkit.
    *
    * @return \Drupal\Core\Image\ImageInterface
    *   An Image object.
    *
    * @see ImageFactory::setToolkitId()
    */
-  public function get($source, $toolkit_id = '') {
-    $toolkit_id = empty($toolkit_id) ? $this->toolkitId : $toolkit_id;
-    return new Image($source, $this->toolkitManager->createInstance($toolkit_id));
+  public function get($source = NULL, $toolkit_id = NULL) {
+    $toolkit_id = $toolkit_id ?: $this->toolkitId;
+    return new Image($this->toolkitManager->createInstance($toolkit_id), $source);
   }
 }
diff --git a/core/lib/Drupal/Core/Image/ImageInterface.php b/core/lib/Drupal/Core/Image/ImageInterface.php
index 344b34e..7e0e1a5 100644
--- a/core/lib/Drupal/Core/Image/ImageInterface.php
+++ b/core/lib/Drupal/Core/Image/ImageInterface.php
@@ -31,16 +31,16 @@ public function isExisting();
   /**
    * Returns the height of the image.
    *
-   * @return int
-   *   The height of the image, or 0 if the image is invalid.
+   * @return int|null
+   *   The height of the image, or NULL if the image is invalid.
    */
   public function getHeight();
 
   /**
    * Returns the width of the image.
    *
-   * @return int
-   *   The width of the image, or 0 if the image is invalid.
+   * @return int|null
+   *   The width of the image, or NULL if the image is invalid.
    */
   public function getWidth();
 
diff --git a/core/lib/Drupal/Core/ImageToolkit/ImageToolkitInterface.php b/core/lib/Drupal/Core/ImageToolkit/ImageToolkitInterface.php
index 8ca05a2..177057b 100644
--- a/core/lib/Drupal/Core/ImageToolkit/ImageToolkitInterface.php
+++ b/core/lib/Drupal/Core/ImageToolkit/ImageToolkitInterface.php
@@ -190,9 +190,9 @@ public function scaleAndCrop(ImageInterface $image, $width, $height);
    * @param \Drupal\Core\Image\ImageInterface $image
    *   An image object.
    *
-   * @return array|FALSE
-   *   FALSE, if the file could not be found or is not an image. Otherwise, a
-   *   keyed array containing information about the image:
+   * @return array
+   *   If the file could not be found or is not an image, an empty array;
+   *   otherwise, a keyed array containing information about the image:
    *   - "type": Image type represented as an IMAGETYPE_* constant.
    *
    * @see \Drupal\Core\Image\ImageInterface::processInfo()
@@ -205,8 +205,8 @@ public function getInfo(ImageInterface $image);
    * @param \Drupal\Core\Image\ImageInterface $image
    *   An image object.
    *
-   * @return int
-   *   The height of the image, or 0 if the image is invalid.
+   * @return int|null
+   *   The height of the image, or NULL if the image is invalid.
    */
   public function getHeight(ImageInterface $image);
 
@@ -216,8 +216,8 @@ public function getHeight(ImageInterface $image);
    * @param \Drupal\Core\Image\ImageInterface $image
    *   An image object.
    *
-   * @return int
-   *   The width of the image, or 0 if the image is invalid.
+   * @return int|null
+   *   The width of the image, or NULL if the image is invalid.
    */
   public function getWidth(ImageInterface $image);
 
diff --git a/core/modules/system/lib/Drupal/system/Plugin/ImageToolkit/GDToolkit.php b/core/modules/system/lib/Drupal/system/Plugin/ImageToolkit/GDToolkit.php
index b6ce30c..e067014 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/ImageToolkit/GDToolkit.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/ImageToolkit/GDToolkit.php
@@ -292,16 +292,11 @@ public function save(ImageInterface $image, $destination) {
    * {@inheritdoc}
    */
   public function getInfo(ImageInterface $image) {
-    $details = FALSE;
+    $details = array();
     $data = getimagesize($image->getSource());
 
     if (isset($data) && is_array($data) && in_array($data[2], static::supportedTypes())) {
-      $details = array(
-        'type'      => $data[2],
-      );
-    }
-
-    if ($details) {
+      $details['type'] = $data[2];
       $this->load($image->getSource(), $details);
     }
     return $details;
@@ -356,14 +351,14 @@ public function createTmp($type, $width, $height) {
    * {@inheritdoc}
    */
   public function getWidth(ImageInterface $image) {
-    return $this->getResource() ? imagesx($this->getResource()) : 0;
+    return $this->getResource() ? imagesx($this->getResource()) : NULL;
   }
 
   /**
    * {@inheritdoc}
    */
   public function getHeight(ImageInterface $image) {
-    return $this->getResource() ? imagesy($this->getResource()) : 0;
+    return $this->getResource() ? imagesy($this->getResource()) : NULL;
   }
 
   /**
diff --git a/core/modules/system/tests/modules/image_test/lib/Drupal/image_test/Plugin/ImageToolkit/TestToolkit.php b/core/modules/system/tests/modules/image_test/lib/Drupal/image_test/Plugin/ImageToolkit/TestToolkit.php
index 8ee44dd..11fa771 100644
--- a/core/modules/system/tests/modules/image_test/lib/Drupal/image_test/Plugin/ImageToolkit/TestToolkit.php
+++ b/core/modules/system/tests/modules/image_test/lib/Drupal/image_test/Plugin/ImageToolkit/TestToolkit.php
@@ -25,14 +25,14 @@ class TestToolkit extends ImageToolkitBase {
    *
    * @var int
    */
-  protected $width = 0;
+  protected $width;
 
   /**
    * The height of the image.
    *
    * @var int
    */
-  protected $height = 0;
+  protected $height;
 
   /**
    * {@inheritdoc}
@@ -65,16 +65,11 @@ public function settingsFormSubmit($form, &$form_state) {
   public function getInfo(ImageInterface $image) {
     $this->logCall('get_info', array($image));
 
-    $details = FALSE;
+    $details = array();
     $data = getimagesize($image->getSource());
 
     if (isset($data) && is_array($data) && in_array($data[2], static::supportedTypes())) {
-      $details = array(
-        'type'      => $data[2],
-      );
-    }
-
-    if ($details) {
+      $details['type'] = $data[2];
       $this->width = $data[0];
       $this->height = $data[1];
       $this->load($image->getSource(), $details);
diff --git a/core/tests/Drupal/Tests/Core/Image/ImageTest.php b/core/tests/Drupal/Tests/Core/Image/ImageTest.php
index 43a8740..2eebde5 100644
--- a/core/tests/Drupal/Tests/Core/Image/ImageTest.php
+++ b/core/tests/Drupal/Tests/Core/Image/ImageTest.php
@@ -46,7 +46,7 @@ protected function setUp() {
       ->method('getPluginId')
       ->will($this->returnValue('gd'));
 
-    $this->image = new Image($this->source, $this->toolkit);
+    $this->image = new Image($this->toolkit, $this->source);
   }
 
   /**
@@ -176,7 +176,7 @@ public function testChmodFails() {
    */
   public function testProcessInfoFails() {
     $toolkit = $this->getToolkitMock();
-    $image = new Image('magic-foobars.png', $toolkit);
+    $image = new Image($toolkit, 'magic-foobars.png');
 
     $this->assertFalse($image->isExisting());
   }
@@ -186,7 +186,7 @@ public function testProcessInfoFails() {
    */
   public function testScaleWidth() {
     $toolkit = $this->getToolkitMock(array('resize'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->any())
       ->method('resize')
@@ -200,7 +200,7 @@ public function testScaleWidth() {
    */
   public function testScaleHeight() {
     $toolkit = $this->getToolkitMock(array('resize'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->any())
       ->method('resize')
@@ -214,7 +214,7 @@ public function testScaleHeight() {
    */
   public function testScaleSame() {
     $toolkit = $this->getToolkitMock(array('resize'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     // Dimensions are the same, resize should not be called.
     $toolkit->expects($this->never())
@@ -230,7 +230,7 @@ public function testScaleSame() {
    */
   public function testScaleAndCropWidth() {
     $toolkit = $this->getToolkitMock(array('resize', 'crop'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('resize')
@@ -249,7 +249,7 @@ public function testScaleAndCropWidth() {
    */
   public function testScaleAndCropHeight() {
     $toolkit = $this->getToolkitMock(array('resize', 'crop'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('resize')
@@ -268,7 +268,7 @@ public function testScaleAndCropHeight() {
    */
   public function testScaleAndCropFails() {
     $toolkit = $this->getToolkitMock(array('resize', 'crop'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('resize')
@@ -304,7 +304,7 @@ public function testScaleAndCropFails() {
    */
   public function testCrop() {
     $toolkit = $this->getToolkitMock(array('crop'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('crop')
@@ -328,7 +328,7 @@ public function testCrop() {
    */
   public function testDesaturate() {
     $toolkit = $this->getToolkitMock(array('desaturate'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('desaturate');
@@ -340,7 +340,7 @@ public function testDesaturate() {
    */
   public function testRotate() {
     $toolkit = $this->getToolkitMock(array('rotate'));
-    $image = new Image($this->source, $toolkit);
+    $image = new Image($toolkit, $this->source);
 
     $toolkit->expects($this->once())
       ->method('rotate');