diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index eab406222a..d1735249ab 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -379,26 +379,33 @@ function wp_constrain_dimensions( $current_width, $current_height, $max_width=0,
 	$smaller_ratio = min( $width_ratio, $height_ratio );
 	$larger_ratio  = max( $width_ratio, $height_ratio );
 
-	if ( intval( $current_width * $larger_ratio ) > $max_width || intval( $current_height * $larger_ratio ) > $max_height )
+	if ( (int) round( $current_width * $larger_ratio ) > $max_width || (int) round( $current_height * $larger_ratio ) > $max_height ) {
  		// The larger ratio is too big. It would result in an overflow.
 		$ratio = $smaller_ratio;
-	else
+	} else {
 		// The larger ratio fits, and is likely to be a more "snug" fit.
 		$ratio = $larger_ratio;
+	}
 
 	// Very small dimensions may result in 0, 1 should be the minimum.
-	$w = max ( 1, intval( $current_width  * $ratio ) );
-	$h = max ( 1, intval( $current_height * $ratio ) );
+	$w = max ( 1, (int) round( $current_width  * $ratio ) );
+	$h = max ( 1, (int) round( $current_height * $ratio ) );
 
 	// Sometimes, due to rounding, we'll end up with a result like this: 465x700 in a 177x177 box is 117x176... a pixel short
 	// We also have issues with recursive calls resulting in an ever-changing result. Constraining to the result of a constraint should yield the original result.
 	// Thus we look for dimensions that are one pixel shy of the max value and bump them up
-	if ( $did_width && $w == $max_width - 1 )
-		$w = $max_width; // Round it up
-	if ( $did_height && $h == $max_height - 1 )
-		$h = $max_height; // Round it up
 
-	return array( $w, $h );
+	// Note: $did_width means it is possible $smaller_ratio == $width_ratio.
+	if ( $did_width && $w == $max_width - 1 ) {
+		$w = $max_width; // Round it up
+	}
+
+	// Note: $did_height means it is possible $smaller_ratio == $height_ratio.
+	if ( $did_height && $h == $max_height - 1 ) {
+		$h = $max_height; // Round it up
+	}
+
+	return apply_filters( 'wp_constrain_dimensions', array( $w, $h ), $current_width, $current_height, $max_width, $max_height );
 }
 
 /**
@@ -459,12 +466,12 @@ function image_resize_dimensions($orig_w, $orig_h, $dest_w, $dest_h, $crop = fal
 		$new_w = min($dest_w, $orig_w);
 		$new_h = min($dest_h, $orig_h);
 
-		if ( !$new_w ) {
-			$new_w = intval($new_h * $aspect_ratio);
+		if ( ! $new_w ) {
+			$new_w = (int) round( $new_h * $aspect_ratio );
 		}
 
-		if ( !$new_h ) {
-			$new_h = intval($new_w / $aspect_ratio);
+		if ( ! $new_h ) {
+			$new_h = (int) round( $new_w / $aspect_ratio );
 		}
 
 		$size_ratio = max($new_w / $orig_w, $new_h / $orig_h);
diff --git a/tests/phpunit/tests/image/editor_gd.php b/tests/phpunit/tests/image/editor_gd.php
index 14dcd985ff..510ace0479 100644
--- a/tests/phpunit/tests/image/editor_gd.php
+++ b/tests/phpunit/tests/image/editor_gd.php
@@ -282,9 +282,9 @@ class Tests_Image_Editor_GD extends WP_Image_UnitTestCase {
 
 			// #0
 			array(
-				'file'      => 'waffles-10x6.jpg',
+				'file'      => 'waffles-10x7.jpg',
 				'width'     => 10,
-				'height'    => 6,
+				'height'    => 7,
 				'mime-type' => 'image/jpeg',
 			),
 
@@ -322,16 +322,16 @@ class Tests_Image_Editor_GD extends WP_Image_UnitTestCase {
 
 			// #5
 			array(
-				'file'      => 'waffles-55x36.jpg',
+				'file'      => 'waffles-55x37.jpg',
 				'width'     => 55,
-				'height'    => 36,
+				'height'    => 37,
 				'mime-type' => 'image/jpeg',
 			),
 
 			// #6
 			array(
-				'file'      => 'waffles-82x55.jpg',
-				'width'     => 82,
+				'file'      => 'waffles-83x55.jpg',
+				'width'     => 83,
 				'height'    => 55,
 				'mime-type' => 'image/jpeg',
 			),
diff --git a/tests/phpunit/tests/image/editor_imagick.php b/tests/phpunit/tests/image/editor_imagick.php
index b77ae065f3..4553446188 100644
--- a/tests/phpunit/tests/image/editor_imagick.php
+++ b/tests/phpunit/tests/image/editor_imagick.php
@@ -282,9 +282,9 @@ class Tests_Image_Editor_Imagick extends WP_Image_UnitTestCase {
 
 			// #0
 			array(
-				'file'      => 'waffles-10x6.jpg',
+				'file'      => 'waffles-10x7.jpg',
 				'width'     => 10,
-				'height'    => 6,
+				'height'    => 7,
 				'mime-type' => 'image/jpeg',
 			),
 
@@ -322,16 +322,16 @@ class Tests_Image_Editor_Imagick extends WP_Image_UnitTestCase {
 
 			// #5
 			array(
-				'file'      => 'waffles-55x36.jpg',
+				'file'      => 'waffles-55x37.jpg',
 				'width'     => 55,
-				'height'    => 36,
+				'height'    => 37,
 				'mime-type' => 'image/jpeg',
 			),
 
 			// #6
 			array(
-				'file'      => 'waffles-82x55.jpg',
-				'width'     => 82,
+				'file'      => 'waffles-83x55.jpg',
+				'width'     => 83,
 				'height'    => 55,
 				'mime-type' => 'image/jpeg',
 			),
diff --git a/tests/phpunit/tests/image/resize.php b/tests/phpunit/tests/image/resize.php
index 3bd4ef17b1..3967232223 100644
--- a/tests/phpunit/tests/image/resize.php
+++ b/tests/phpunit/tests/image/resize.php
@@ -13,7 +13,7 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_jpg() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/test-image.jpg', 25, 25 );
 
-		$this->assertEquals( 'test-image-25x25.jpg', basename($image) );
+		$this->assertEquals( 'test-image-25x25.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 25, $w );
 		$this->assertEquals( 25, $h );
@@ -25,7 +25,12 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_png() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/test-image.png', 25, 25 );
 
-		$this->assertEquals( 'test-image-25x25.png', basename($image) );
+		if ( ! is_string( $image ) ) {  // WP_Error, stop GLib-GObject-CRITICAL assertion
+			$this->markTestSkipped( sprintf( 'No PNG support in the editor engine %s on this system', $this->editor_engine ) );
+			return;
+		}
+
+		$this->assertEquals( 'test-image-25x25.png', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 25, $w );
 		$this->assertEquals( 25, $h );
@@ -37,7 +42,12 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_gif() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/test-image.gif', 25, 25 );
 
-		$this->assertEquals( 'test-image-25x25.gif', basename($image) );
+		if ( ! is_string( $image ) ) {  // WP_Error, stop GLib-GObject-CRITICAL assertion
+			$this->markTestSkipped( sprintf( 'No GIF support in the editor engine %s on this system', $this->editor_engine ) );
+			return;
+		}
+
+		$this->assertEquals( 'test-image-25x25.gif', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 25, $w );
 		$this->assertEquals( 25, $h );
@@ -57,9 +67,9 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_128x96() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 128, 96 );
 
-		$this->assertEquals( '2007-06-17DSC_4173-63x96.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-64x96.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
-		$this->assertEquals( 63, $w );
+		$this->assertEquals( 64, $w );
 		$this->assertEquals( 96, $h );
 		$this->assertEquals( IMAGETYPE_JPEG, $type );
 
@@ -69,10 +79,10 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_128x0() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 128, 0 );
 
-		$this->assertEquals( '2007-06-17DSC_4173-128x192.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-128x193.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 128, $w );
-		$this->assertEquals( 192, $h );
+		$this->assertEquals( 193, $h );
 		$this->assertEquals( IMAGETYPE_JPEG, $type );
 
 		unlink( $image );
@@ -81,9 +91,9 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_0x96() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 0, 96 );
 
-		$this->assertEquals( '2007-06-17DSC_4173-63x96.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-64x96.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
-		$this->assertEquals( 63, $w );
+		$this->assertEquals( 64, $w );
 		$this->assertEquals( 96, $h );
 		$this->assertEquals( IMAGETYPE_JPEG, $type );
 
@@ -93,7 +103,7 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_150x150_crop() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 150, 150, true );
 
-		$this->assertEquals( '2007-06-17DSC_4173-150x150.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-150x150.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 150, $w );
 		$this->assertEquals( 150, $h );
@@ -105,7 +115,7 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_150x100_crop() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 150, 100, true );
 
-		$this->assertEquals( '2007-06-17DSC_4173-150x100.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-150x100.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 150, $w );
 		$this->assertEquals( 100, $h );
@@ -117,7 +127,7 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	function test_resize_thumb_50x150_crop() {
 		$image = $this->resize_helper( DIR_TESTDATA.'/images/2007-06-17DSC_4173.JPG', 50, 150, true );
 
-		$this->assertEquals( '2007-06-17DSC_4173-50x150.jpg', basename($image) );
+		$this->assertEquals( '2007-06-17DSC_4173-50x150.jpg', basename( $image ) );
 		list($w, $h, $type) = getimagesize($image);
 		$this->assertEquals( 50, $w );
 		$this->assertEquals( 150, $h );
@@ -142,6 +152,12 @@ abstract class WP_Tests_Image_Resize_UnitTestCase extends WP_Image_UnitTestCase
 	 * @ticket 6821
 	 */
 	public function test_resize_bad_image() {
+
+		if ( $this->editor_engine == 'WP_Image_Editor_Imagick' ) {
+			$this->markTestSkipped( sprintf( 'Avoid GLib-GObject-CRITICAL assertion in %s', $this->editor_engine ) );
+			return;
+		}
+
 		$image = $this->resize_helper( DIR_TESTDATA.'/export/crazy-cdata.xml', 25, 25 );
 		$this->assertInstanceOf( 'WP_Error', $image );
 		$this->assertEquals( 'invalid_image', $image->get_error_code() );
diff --git a/tests/phpunit/tests/image/size.php b/tests/phpunit/tests/image/size.php
index c7cb51b8a7..497946c829 100644
--- a/tests/phpunit/tests/image/size.php
+++ b/tests/phpunit/tests/image/size.php
@@ -13,13 +13,16 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		// no constraint - should have no effect
 		$out = wp_constrain_dimensions(640, 480, 0, 0);
-		$this->assertEquals(array(640, 480), $out);
+		$this->assertSame( array( 640, 480 ), $out );
 
 		$out = wp_constrain_dimensions(640, 480);
-		$this->assertEquals(array(640, 480), $out);
+		$this->assertSame( array( 640, 480 ), $out );
 
 		$out = wp_constrain_dimensions(0, 0, 0, 0);
-		$this->assertEquals(array(0, 0), $out);
+		$this->assertSame( array( 0, 0 ), $out );
+
+		$out = wp_constrain_dimensions(465, 700, 177, 177);
+		$this->assertSame( array( 118, 177 ), $out );
 	}
 
 	function test_constrain_dims_smaller() {
@@ -28,13 +31,13 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		// image size is smaller than the constraint - no effect
 		$out = wp_constrain_dimensions(500, 600, 1024, 768);
-		$this->assertEquals(array(500, 600), $out);
+		$this->assertSame( array( 500, 600 ), $out );
 
 		$out = wp_constrain_dimensions(500, 600, 0, 768);
-		$this->assertEquals(array(500, 600), $out);
+		$this->assertSame( array( 500, 600 ), $out );
 
 		$out = wp_constrain_dimensions(500, 600, 1024, 0);
-		$this->assertEquals(array(500, 600), $out);
+		$this->assertSame( array( 500, 600 ), $out );
 	}
 
 	function test_constrain_dims_equal() {
@@ -43,13 +46,13 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		// image size is equal to the constraint - no effect
 		$out = wp_constrain_dimensions(1024, 768, 1024, 768);
-		$this->assertequals(array(1024, 768), $out);
+		$this->assertSame( array( 1024, 768 ), $out );
 
 		$out = wp_constrain_dimensions(1024, 768, 0, 768);
-		$this->assertequals(array(1024, 768), $out);
+		$this->assertSame( array( 1024, 768 ), $out );
 
 		$out = wp_constrain_dimensions(1024, 768, 1024, 0);
-		$this->assertequals(array(1024, 768), $out);
+		$this->assertSame( array( 1024, 768 ), $out );
 	}
 
 	function test_constrain_dims_larger() {
@@ -58,23 +61,23 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		// image size is larger than the constraint - result should be constrained
 		$out = wp_constrain_dimensions(1024, 768, 500, 600);
-		$this->assertequals(array(500, 375), $out);
+		$this->assertSame( array( 500, 375 ), $out );
 
 		$out = wp_constrain_dimensions(1024, 768, 0, 600);
-		$this->assertequals(array(800, 600), $out);
+		$this->assertSame( array( 800, 600 ), $out );
 
 		$out = wp_constrain_dimensions(1024, 768, 500, 0);
-		$this->assertequals(array(500, 375), $out);
+		$this->assertSame( array( 500, 375 ), $out );
 
 		// also try a portrait oriented image
 		$out = wp_constrain_dimensions(300, 800, 500, 600);
-		$this->assertequals(array(225, 600), $out);
+		$this->assertSame( array( 225, 600 ), $out );
 
 		$out = wp_constrain_dimensions(300, 800, 0, 600);
-		$this->assertequals(array(225, 600), $out);
+		$this->assertSame( array( 225, 600 ), $out );
 
 		$out = wp_constrain_dimensions(300, 800, 200, 0);
-		$this->assertequals(array(200, 533), $out);
+		$this->assertSame( array( 200, 533 ), $out );
 	}
 
 	function test_constrain_dims_boundary() {
@@ -83,17 +86,17 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		// one dimension is larger than the constraint, one smaller - result should be constrained
 		$out = wp_constrain_dimensions(1024, 768, 500, 800);
-		$this->assertequals(array(500, 375), $out);
+		$this->assertSame( array( 500, 375 ), $out );
 
 		$out = wp_constrain_dimensions(1024, 768, 2000, 700);
-		$this->assertequals(array(933, 700), $out);
+		$this->assertSame( array( 933, 700 ), $out );
 
 		// portrait
 		$out = wp_constrain_dimensions(768, 1024, 800, 500);
-		$this->assertequals(array(375, 500), $out);
+		$this->assertSame( array( 375, 500 ), $out );
 
 		$out = wp_constrain_dimensions(768, 1024, 2000, 700);
-		$this->assertequals(array(525, 700), $out);
+		$this->assertSame( array( 525, 700 ), $out );
 	}
 
 	/**
@@ -101,10 +104,10 @@ class Tests_Image_Size extends WP_UnitTestCase {
 	 */
 	function test_shrink_dimensions_default() {
 		$out = wp_shrink_dimensions(640, 480);
-		$this->assertEquals(array(128, 96), $out);
+		$this->assertSame( array( 128, 96 ), $out );
 
 		$out = wp_shrink_dimensions(480, 640);
-		$this->assertEquals(array(72, 96), $out);
+		$this->assertSame( array( 72, 96 ), $out );
 	}
 
 	/**
@@ -113,10 +116,10 @@ class Tests_Image_Size extends WP_UnitTestCase {
 	function test_shrink_dimensions_smaller() {
 		// image size is smaller than the constraint - no effect
 		$out = wp_shrink_dimensions(500, 600, 1024, 768);
-		$this->assertEquals(array(500, 600), $out);
+		$this->assertSame( array( 500, 600 ), $out );
 
 		$out = wp_shrink_dimensions(600, 500, 1024, 768);
-		$this->assertEquals(array(600, 500), $out);
+		$this->assertSame( array( 600, 500 ), $out );
 	}
 
 	/**
@@ -125,10 +128,10 @@ class Tests_Image_Size extends WP_UnitTestCase {
 	function test_shrink_dimensions_equal() {
 		// image size is equal to the constraint - no effect
 		$out = wp_shrink_dimensions(500, 600, 500, 600);
-		$this->assertEquals(array(500, 600), $out);
+		$this->assertSame( array( 500, 600 ), $out );
 
 		$out = wp_shrink_dimensions(600, 500, 600, 500);
-		$this->assertEquals(array(600, 500), $out);
+		$this->assertSame( array( 600, 500 ), $out );
 	}
 
 	/**
@@ -137,10 +140,10 @@ class Tests_Image_Size extends WP_UnitTestCase {
 	function test_shrink_dimensions_larger() {
 		// image size is larger than the constraint - result should be constrained
 		$out = wp_shrink_dimensions(1024, 768, 500, 600);
-		$this->assertequals(array(500, 375), $out);
+		$this->assertSame( array( 500, 375 ), $out );
 
 		$out = wp_shrink_dimensions(300, 800, 500, 600);
-		$this->assertequals(array(225, 600), $out);
+		$this->assertSame( array( 225, 600 ), $out );
 	}
 
 	/**
@@ -149,25 +152,25 @@ class Tests_Image_Size extends WP_UnitTestCase {
 	function test_shrink_dimensions_boundary() {
 		// one dimension is larger than the constraint, one smaller - result should be constrained
 		$out = wp_shrink_dimensions(1024, 768, 500, 800);
-		$this->assertequals(array(500, 375), $out);
+		$this->assertSame( array( 500, 375 ), $out );
 
 		$out = wp_shrink_dimensions(1024, 768, 2000, 700);
-		$this->assertequals(array(933, 700), $out);
+		$this->assertSame( array( 933, 700 ), $out );
 
 		// portrait
 		$out = wp_shrink_dimensions(768, 1024, 800, 500);
-		$this->assertequals(array(375, 500), $out);
+		$this->assertSame( array( 375, 500 ), $out );
 
 		$out = wp_shrink_dimensions(768, 1024, 2000, 700);
-		$this->assertequals(array(525, 700), $out);
+		$this->assertSame( array( 525, 700 ), $out );
 	}
 
 	function test_constrain_size_for_editor_thumb() {
 		$out = image_constrain_size_for_editor(600, 400, 'thumb');
-		$this->assertEquals(array(150, 100), $out);
+		$this->assertSame( array( 150, 100 ), $out );
 
 		$out = image_constrain_size_for_editor(64, 64, 'thumb');
-		$this->assertEquals(array(64, 64), $out);
+		$this->assertSame( array( 64, 64 ), $out );
 	}
 
 	function test_constrain_size_for_editor_medium() {
@@ -181,18 +184,18 @@ class Tests_Image_Size extends WP_UnitTestCase {
 		update_option('medium_size_h', 0);
 
 		$out = image_constrain_size_for_editor(600, 400, 'medium');
-		$this->assertEquals(array(500, 333), $out);
+		$this->assertSame( array( 500, 333 ), $out );
 
 		$out = image_constrain_size_for_editor(400, 600, 'medium');
-		$this->assertEquals(array(400, 600), $out);
+		$this->assertSame( array( 400, 600 ), $out );
 
 		$out = image_constrain_size_for_editor(64, 64, 'medium');
-		$this->assertEquals(array(64, 64), $out);
+		$this->assertSame( array( 64, 64 ), $out );
 
 		// content_width should be ignored
 		$content_width = 350;
 		$out = image_constrain_size_for_editor(600, 400, 'medium');
-		$this->assertEquals(array(500, 333), $out);
+		$this->assertSame( array( 500, 333 ), $out );
 
 		$content_width = $_content_width;
 	}
@@ -204,19 +207,19 @@ class Tests_Image_Size extends WP_UnitTestCase {
 
 		$content_width = 400;
 		$out = image_constrain_size_for_editor(600, 400, 'full');
-		$this->assertEquals(array(600, 400), $out);
+		$this->assertSame( array( 600, 400 ), $out );
 
 		$out = image_constrain_size_for_editor(64, 64, 'full');
-		$this->assertEquals(array(64, 64), $out);
+		$this->assertSame( array( 64, 64 ), $out );
 
 		// content_width default is 500
 		$content_width = 0;
 
 		$out = image_constrain_size_for_editor(600, 400, 'full');
-		$this->assertEquals(array(600, 400), $out);
+		$this->assertSame( array( 600, 400 ), $out );
 
 		$out = image_constrain_size_for_editor(64, 64, 'full');
-		$this->assertEquals(array(64, 64), $out);
+		$this->assertSame( array( 64, 64 ), $out );
 
 		$content_width = $_content_width;
 	}