diff --git src/wp-includes/media.php src/wp-includes/media.php
index c02aabc..6b246d1 100644
--- src/wp-includes/media.php
+++ src/wp-includes/media.php
@@ -580,41 +580,47 @@ function image_make_intermediate_size( $file, $width, $height, $crop = false ) {
  * @param array|string $size Optional, default is 'thumbnail'. Size of image, either array or string.
  * @return bool|array False on failure or array of file path, width, and height on success.
  */
-function image_get_intermediate_size($post_id, $size='thumbnail') {
+function image_get_intermediate_size( $post_id, $size='thumbnail' ) {
 	if ( !is_array( $imagedata = wp_get_attachment_metadata( $post_id ) ) )
 		return false;
 
 	// get the best one for a specified set of dimensions
-	if ( is_array($size) && !empty($imagedata['sizes']) ) {
-		$areas = array();
+	if ( is_array($size) && !empty( $imagedata['sizes'] ) ) {
+		$candidates = array();
 
 		foreach ( $imagedata['sizes'] as $_size => $data ) {
-			// already cropped to width or height; so use this size
-			if ( ( $data['width'] == $size[0] && $data['height'] <= $size[1] ) || ( $data['height'] == $size[1] && $data['width'] <= $size[0] ) ) {
+			// If there's an exact match to an existing image size, short circuit.
+			if ( ( $data['width'] == $size[0] && $data['height'] == $size[1] ) ) {
 				$file = $data['file'];
 				list($width, $height) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
 				return compact( 'file', 'width', 'height' );
 			}
-			// add to lookup table: area => size
-			$areas[$data['width'] * $data['height']] = $_size;
+			// If it's not an exact match but it's at least the dimensions requested.
+			if ( ( $data['width'] >= $size[0] ) && ( $data['height'] >= $size[1] ) ) {
+				$candidates[$data['width'] * $data['height']] = $_size;
+			}
 		}
-		if ( !$size || !empty($areas) ) {
+
+		if ( !empty($candidates) ) {
 			// find for the smallest image not smaller than the desired size
-			ksort($areas);
-			foreach ( $areas as $_size ) {
+			ksort($candidates);
+			foreach ( $candidates as $_size ) {
 				$data = $imagedata['sizes'][$_size];
-				if ( $data['width'] >= $size[0] || $data['height'] >= $size[1] ) {
-					// Skip images with unexpectedly divergent aspect ratios (crops)
-					// First, we calculate what size the original image would be if constrained to a box the size of the current image in the loop
-					$maybe_cropped = image_resize_dimensions($imagedata['width'], $imagedata['height'], $data['width'], $data['height'], false );
-					// If the size doesn't match within one pixel, then it is of a different aspect ratio, so we skip it, unless it's the thumbnail size
-					if ( 'thumbnail' != $_size && ( !$maybe_cropped || ( $maybe_cropped[4] != $data['width'] && $maybe_cropped[4] + 1 != $data['width'] ) || ( $maybe_cropped[5] != $data['height'] && $maybe_cropped[5] + 1 != $data['height'] ) ) )
-						continue;
-					// If we're still here, then we're going to use this size
-					$file = $data['file'];
-					list($width, $height) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
-					return compact( 'file', 'width', 'height' );
-				}
+
+				// Skip images with unexpectedly divergent aspect ratios (crops)
+				// First, we calculate what size the original image would be if constrained to a box the size of the current image in the loop
+				$maybe_cropped = image_resize_dimensions($imagedata['width'], $imagedata['height'], $data['width'], $data['height'], false );
+				// If the size doesn't match within one pixel, then it is of a different aspect ratio, so we skip it, unless it's the thumbnail size
+				if ( 'thumbnail' != $_size &&
+	        ( !$maybe_cropped
+	          || ( $maybe_cropped[4] != $data['width'] && $maybe_cropped[4] + 1 != $data['width'] )
+	          || ( $maybe_cropped[5] != $data['height'] && $maybe_cropped[5] + 1 != $data['height'] )
+	        ) )
+	        continue;
+				// If we're still here, then we're going to use this size
+				$file = $data['file'];
+				list($width, $height) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
+				return compact( 'file', 'width', 'height' );
 			}
 		}
 	}
diff --git tests/phpunit/tests/image/intermediate_size.php tests/phpunit/tests/image/intermediate_size.php
index 73728e5..5efe0e7 100644
--- tests/phpunit/tests/image/intermediate_size.php
+++ tests/phpunit/tests/image/intermediate_size.php
@@ -10,6 +10,38 @@ class Tests_Image_Intermediate_Size extends WP_UnitTestCase {
 		parent::tearDown();
 	}
 
+	/**
+	 * Upload files and create attachements for testing
+	 */
+	private function _make_attachment( $file, $parent_post_id = 0 ) {
+		$contents = file_get_contents($file);
+		$upload = wp_upload_bits(basename($file), null, $contents);
+
+		$type = '';
+		if ( !empty($upload['type']) ) {
+			$type = $upload['type'];
+		} else {
+			$mime = wp_check_filetype( $upload['file'] );
+			if ($mime)
+			$type = $mime['type'];
+		}
+
+		$attachment = array(
+			'post_title' => basename( $upload['file'] ),
+			'post_content' => '',
+			'post_type' => 'attachment',
+			'post_parent' => $parent_post_id,
+			'post_mime_type' => $type,
+			'guid' => $upload[ 'url' ],
+		);
+
+		// Save the data
+		$id = wp_insert_attachment( $attachment, $upload[ 'file' ], $parent_post_id );
+		wp_update_attachment_metadata( $id, wp_generate_attachment_metadata( $id, $upload['file'] ) );
+
+		return $this->ids[] = $id;
+	}
+
 	function test_make_intermediate_size_no_size() {
 		$image = image_make_intermediate_size( DIR_TESTDATA . '/images/a2-small.jpg', 0, 0, false );
 
@@ -49,4 +81,104 @@ class Tests_Image_Intermediate_Size extends WP_UnitTestCase {
 
 		unlink( DIR_TESTDATA . '/images/a2-small-100x75.jpg' );
 	}
+
+	/**
+	* @ticket 17626
+	*/
+	function test_get_intermediate_sizes_by_name() {
+		add_image_size( 'test-size', 330, 220, true );
+
+		$file = DIR_TESTDATA . '/images/waffles.jpg';
+		$id = $this->_make_attachment( $file, 0 );
+
+		// look for a size by name
+		$image = image_get_intermediate_size( $id, 'test-size' );
+
+		// test for the expected string because the array will by definition
+		// return with the correct height and width attributes
+		$this->assertNotFalse( strpos( $image['file'], '330x220' ) );
+
+		// cleanup
+		remove_image_size('test-size');
+	}
+
+	/**
+	* @ticket 17626
+	*/
+	function test_get_intermediate_sizes_by_array_exact() {
+		// Only one dimention match shouldn't return false positive (see: 17626)
+		add_image_size( 'test-size', 330, 220, true );
+		add_image_size( 'false-height', 330, 400, true);
+		add_image_size( 'false-width', 600, 220, true);
+
+		$file = DIR_TESTDATA . '/images/waffles.jpg';
+		$id = $this->_make_attachment( $file, 0 );
+
+		// look for a size by array that exists
+		// note: staying larger than 300px to miss default medium crop
+		$image = image_get_intermediate_size( $id, array(330,220) );
+
+		// test for the expected string because the array will by definition
+		// return with the correct height and width attributes
+		$this->assertNotFalse( strpos( $image['file'], '330x220' ) );
+
+		// cleanup
+		remove_image_size('test-size');
+		remove_image_size('false-height');
+		remove_image_size('false-width');
+	}
+
+	/**
+	* @ticket 17626
+	*/
+	function test_get_intermediate_sizes_by_array_nearest() {
+		// If an exact size is not found, it should be returned
+		// If not, find nearest size that is larger (see: 17626)
+		add_image_size( 'test-size', 450, 300, true );
+		add_image_size( 'false-height', 330, 100, true);
+		add_image_size( 'false-width', 150, 220, true);
+
+		$file = DIR_TESTDATA . '/images/waffles.jpg';
+		$id = $this->_make_attachment( $file, 0 );
+
+		// look for a size by array that doesn't exist
+		// note: staying larger than 300px to miss default medium crop
+		$image = image_get_intermediate_size( $id, array(330,220) );
+
+		// you have to test for the string because the image will by definition
+		// return with the correct height and width attributes
+		$this->assertNotFalse( strpos( $image['file'], '450x300' ) );
+
+		// cleanup
+		remove_image_size('test-size');
+		remove_image_size('false-height');
+		remove_image_size('false-width');
+
+	}
+
+	/**
+	* @ticket 17626
+	*/
+	function test_get_intermediate_sizes_by_array_nearest_false() {
+		// If an exact size is not found, it should be returned
+		// If not, find nearest size that is larger, otherwise return false (see: 17626)
+		add_image_size( 'false-height', 330, 100, true);
+		add_image_size( 'false-width', 150, 220, true);
+
+		$file = DIR_TESTDATA . '/images/waffles.jpg';
+		$id = $this->_make_attachment( $file, 0 );
+
+		// look for a size by array that doesn't exist
+		// note: staying larger than 300px to miss default medium crop
+		$image = image_get_intermediate_size( $id, array(330,220) );
+
+		// you have to test for the string because the image will by definition
+		// return with the correct height and width attributes
+		$this->assertFalse( $image );
+
+		// cleanup
+		remove_image_size('false-height');
+		remove_image_size('false-width');
+
+	}
 }