diff --git src/wp-includes/class-wp-image-editor-imagick.php src/wp-includes/class-wp-image-editor-imagick.php
index 7e6ffd1..e366b65 100644
--- src/wp-includes/class-wp-image-editor-imagick.php
+++ src/wp-includes/class-wp-image-editor-imagick.php
@@ -62,25 +62,21 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 			'writeimage',
 			'getimageblob',
 			'getimagegeometry',
-			'getimagedepth',
 			'getimageformat',
 			'setimageformat',
 			'setimagecompression',
 			'setimagecompressionquality',
 			'setimagedepth',
 			'setimagepage',
-			'setimageproperty',
-			'setinterlacescheme',
 			'scaleimage',
 			'cropimage',
 			'rotateimage',
 			'flipimage',
 			'flopimage',
-			'unsharpmaskimage',
 		);
 
 		// Now, test for deep requirements within Imagick.
-		if ( ! ( defined( 'imagick::COMPRESSION_JPEG' ) && defined( 'imagick::FILTER_TRIANGLE' ) ) )
+		if ( ! ( defined( 'imagick::COMPRESSION_JPEG' ) ) )
 			return false;
 
 		if ( array_diff( $required_methods, get_class_methods( 'Imagick' ) ) )
@@ -304,7 +300,7 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 		if ( in_array( $filter_name, $allowed_filters ) && defined( 'Imagick::' . $filter_name ) ) {
 			$filter = constant( 'Imagick::' . $filter_name );
 		} else {
-			$filter = Imagick::FILTER_TRIANGLE;
+			$filter = defnined( Imagick::FILTER_TRIANGLE ) ? Imagick::FILTER_TRIANGLE : false;
 		}
 
 		/**
@@ -327,20 +323,34 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 			 * whenever the output size is less that 1/3 of the original image size (1/3^2 ~= .111),
 			 * unless we would be resampling to a scale smaller than 128x128.
 			 */
-			$resize_ratio = ( $dst_w / $this->size['width'] ) * ( $dst_h / $this->size['height'] );
-			$sample_factor = 5;
+			if ( method_exists( $this->image, 'sampleImage') ) {
+				$resize_ratio = ( $dst_w / $this->size['width'] ) * ( $dst_h / $this->size['height'] );
+				$sample_factor = 5;
 
-			if ( $resize_ratio < .111 && ( $dst_w * $sample_factor > 128 && $dst_h * $sample_factor > 128 ) ) {
-				$this->image->sampleImage( $dst_w * $sample_factor, $dst_h * $sample_factor );
+				if ( $resize_ratio < .111 && ( $dst_w * $sample_factor > 128 && $dst_h * $sample_factor > 128 ) ) {
+					$this->image->sampleImage( $dst_w * $sample_factor, $dst_h * $sample_factor );
+				}
 			}
 
-			// Resize to the final output size.
-			$this->image->setOption( 'filter:support', '2.0' );
-			$this->image->resizeImage( $dst_w, $dst_h, $filter, 1 );
+			/**
+			 * Use resizeImage() when it's availalbe and a valid filter value is set.
+			 * Otherwise, fall back to the scaleImage() method for resizing, which
+			 * results in better image quality over resizeImage() with default filter
+			 * settings and retains backwards compatability with pre 4.5 functionality.
+			 */
+			if ( method_exists( $this->image, 'resizeImage') && $filter ) {
+				$this->image->setOption( 'filter:support', '2.0' );
+				$this->image->resizeImage( $dst_w, $dst_h, $filter, 1 );
+			} else {
+				$this->image->scaleImage( $dst_w, $dst_h );
+			}
 
 			// Set appropriate quality settings after resizing.
 			if ( 'image/jpeg' == $this->mime_type ) {
-				$this->image->unsharpMaskImage( 0.25, 0.25, 8, 0.065 );
+				if ( method_exists( $this->image, 'unsharpMaskImage') ) {
+					$this->image->unsharpMaskImage( 0.25, 0.25, 8, 0.065 );
+				}
+
 				$this->image->setOption( 'jpeg:fancy-upsampling', 'off' );
 			}
 
@@ -362,11 +372,13 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 			}
 
 			// Limit the  bit depth of resized images to 8 bits per channel.
-			if ( 8 < $this->image->getImageDepth() ) {
+			if ( method_exists( $this->image, 'getImageDepth' ) && 8 < $this->image->getImageDepth() ) {
 				$this->image->setImageDepth( 8 );
 			}
 
-			$this->image->setInterlaceScheme( Imagick::INTERLACE_NO );
+			if ( method_exists( $this->image, 'setInterlaceScheme' ) && defined( 'Imagick::INTERLACE_NO' ) ) {
+				$this->image->setInterlaceScheme( Imagick::INTERLACE_NO );
+			}
 
 		}
 		catch ( Exception $e ) {