Aspose.Imaging for .NET

https://github.com/aspose-imaging/Aspose.Imaging-for-.NET/blob/master/Examples/CSharp/ModifyingAndConvertingImages/Deskew.cs

Deskew.cs

class Deskew
    {
        public static void Run()
        {
            string dataDir = RunExamples.GetDataDir_ModifyingAndConvertingImages();

            string fileName = "skewed.png";
            string output = "skewed.out.png";
            string inputFileName = Path.Combine(dataDir, fileName);

            // Get rid of the skewed scan with default parameters
            using (RasterImage image = (RasterImage)Image.Load(inputFileName))
            {
                image.NormalizeAngle(false /*do not resize*/, Color.LightGray /*background color*/);
                image.Save(Path.Combine(dataDir, output));
            }

        }
    }