Check dimensions of dynamic image before resizing it

src/dynimage.rs

@@ -658,14 +658,22 @@ impl DynamicImage {
     }
 
     /// Resize this image using the specified filter algorithm.
-    /// Returns a new image. The image's aspect ratio is preserved.
     /// The image is scaled to the maximum possible size that fits
     /// within the bounds specified by `nwidth` and `nheight`.
+    /// The image's aspect ratio is preserved.
+    /// Returns a new image if the requested image size is different than the already existing one.
+    /// Otherwise the function returns a copy of self.
     pub fn resize(&self, nwidth: u32, nheight: u32, filter: imageops::FilterType) -> DynamicImage {
-        let (width2, height2) =
+        if (nwidth, nheight) == self.dimensions() {
+            // Image is already in the desired dimensions --> no need to resize.
+            return self.clone();
+        }
+        else {
+            let (width2, height2) =
             resize_dimensions(self.width(), self.height(), nwidth, nheight, false);
 
-        self.resize_exact(width2, height2, filter)
+            return self.resize_exact(width2, height2, filter);
+        }
     }
 
     /// Resize this image using the specified filter algorithm.