How to convert TIF to Black-and-White Monochrome TIF

Question

I would like to use Magick.NET https://magick.codeplex.com/wikipage?title=Convert%20image&referringTitle=Documentation

in order to convert TIF to Black-and-White Monochrome TIF but manual does not explain it well.

I have tried this code but I am not sure of this approach is a correct one.

using (MagickImage image = new MagickImage("input.tif"))
{
  image.CompressionMethod = CompressionMethod.Group4;
  image.Write("output.tif");
}

Help needed. Thank you!

Answer 1

I found .NET code to do the same thing without any issues.

http://www.codeproject.com/Articles/15186/Bitonal-TIFF-Image-Converter-for-NET

private void convert_Click(object sender, EventArgs e)
        {
            // Load a bitmap from disk
            Bitmap originalBitmap = new Bitmap(@"..\..\Bitonal-In.tif");

            // Display image
            originalImage.Image = originalBitmap;

            // Convert bitmap to RGB format for drawing
            Bitmap rgbBitmap = Converter.ConvertToRGB(originalBitmap);
            // Convert image to bitonal for saving to file
            Bitmap bitonalBitmap = Converter.ConvertToBitonal(rgbBitmap);

            // Display converted image
            convertedImage.Image = bitonalBitmap;

            // Get an ImageCodecInfo object that represents the TIFF codec.
            ImageCodecInfo imageCodecInfo = GetEncoderInfo("image/tiff");
            System.Drawing.Imaging.Encoder encoder = System.Drawing.Imaging.Encoder.Compression;
            EncoderParameters encoderParameters = new EncoderParameters(1);

            // Save the bitmap as a TIFF file with group IV compression.
            EncoderParameter encoderParameter = new EncoderParameter(encoder, (long)EncoderValue.CompressionCCITT4);
            encoderParameters.Param[0] = encoderParameter;
            bitonalBitmap.Save(@"..\..\Bitonal-Out.tif", imageCodecInfo, encoderParameters);

        }

using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

namespace BitonalConverter
{
    public static class Converter
    {
        public static Bitmap ConvertToRGB(Bitmap original)
        {
            Bitmap newImage = new Bitmap(original.Width, original.Height, PixelFormat.Format32bppArgb);
            newImage.SetResolution(original.HorizontalResolution, original.VerticalResolution);
            using (Graphics g = Graphics.FromImage(newImage))
            {
                g.DrawImageUnscaled(original, 0, 0);
            }
            return newImage;
        }

        public static Bitmap ConvertToBitonal(Bitmap original)
        {
            Bitmap source = null;

            // If original bitmap is not already in 32 BPP, ARGB format, then convert
            if (original.PixelFormat != PixelFormat.Format32bppArgb)
            {
                source = new Bitmap(original.Width, original.Height, PixelFormat.Format32bppArgb);
                source.SetResolution(original.HorizontalResolution, original.VerticalResolution);
                using (Graphics g = Graphics.FromImage(source))
                {
                    g.DrawImageUnscaled(original, 0, 0);
                }
            }
            else
            {
                source = original;
            }

            // Lock source bitmap in memory
            BitmapData sourceData = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

            // Copy image data to binary array
            int imageSize = sourceData.Stride * sourceData.Height;
            byte[] sourceBuffer = new byte[imageSize];
            Marshal.Copy(sourceData.Scan0, sourceBuffer, 0, imageSize);

            // Unlock source bitmap
            source.UnlockBits(sourceData);

            // Create destination bitmap
            Bitmap destination = new Bitmap(source.Width, source.Height, PixelFormat.Format1bppIndexed);
            destination.SetResolution(original.HorizontalResolution, original.VerticalResolution);

            // Lock destination bitmap in memory
            BitmapData destinationData = destination.LockBits(new Rectangle(0, 0, destination.Width, destination.Height), ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);

            // Create destination buffer
            imageSize = destinationData.Stride * destinationData.Height;
            byte[] destinationBuffer = new byte[imageSize];

            int sourceIndex = 0;
            int destinationIndex = 0;
            int pixelTotal = 0;
            byte destinationValue = 0;
            int pixelValue = 128;
            int height = source.Height;
            int width = source.Width;
            int threshold = 500;

            // Iterate lines
            for (int y = 0; y < height; y++)
            {
                sourceIndex = y * sourceData.Stride;
                destinationIndex = y * destinationData.Stride;
                destinationValue = 0;
                pixelValue = 128;

                // Iterate pixels
                for (int x = 0; x < width; x++)
                {
                    // Compute pixel brightness (i.e. total of Red, Green, and Blue values) - Thanks murx
                    //                           B                             G                              R
                    pixelTotal = sourceBuffer[sourceIndex] + sourceBuffer[sourceIndex + 1] + sourceBuffer[sourceIndex + 2];
                    if (pixelTotal > threshold)
                    {
                        destinationValue += (byte)pixelValue;
                    }
                    if (pixelValue == 1)
                    {
                        destinationBuffer[destinationIndex] = destinationValue;
                        destinationIndex++;
                        destinationValue = 0;
                        pixelValue = 128;
                    }
                    else
                    {
                        pixelValue >>= 1;
                    }
                    sourceIndex += 4;
                }
                if (pixelValue != 128)
                {
                    destinationBuffer[destinationIndex] = destinationValue;
                }
            }

            // Copy binary image data to destination bitmap
            Marshal.Copy(destinationBuffer, 0, destinationData.Scan0, imageSize);

            // Unlock destination bitmap
            destination.UnlockBits(destinationData);

            // Dispose of source if not originally supplied bitmap
            if (source != original)
            {
                source.Dispose();
            }

            // Return
            return destination;
        }
    }
}