The output image after cropping is larger than the original size

when I crop an Image using Bitmap.Clone() it creates output larger than the Original Image Size
The Original size is : 5 M
and the Output Cropped image is : 28 M

how can I make cropping without lose quality and with no large size ?
my code is :

private static Image cropImage(Image img, Rectangle cropArea)
       {
           var bmpImage = new Bitmap(img);
           Bitmap bmpCrop = bmpImage.Clone(cropArea, bmpImage.PixelFormat);
           img.Dispose();
           bmpCrop.Save(@"D:\Work\CropImage\CropImage\crop.bmp",bmpImage.RawFormat );
           return (Image)(bmpCrop);
       }

Tags: C#, Image Processing