Question

I’m having a problem with saving a picture. With this code I’m putting two pictures together. But when I save them the quality is worse than the quality of the original pictures.

            Image Image1 = Image.FromFile(openFileDialogOpenPicture1.FileName);
            Image Image2 = Image.FromFile(openFileDialogOpenPicture2.FileName);

            int imageHeight = 0;
            if (Image1.Height > Image2.Height)
                imageHeight = Image1.Height;
            else
                imageHeight = Image2.Height;

            Bitmap finalImage = new System.Drawing.Bitmap(Image1.Width + Image2.Width, imageHeight);
            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(finalImage))
            {
                //set background color
                g.Clear(System.Drawing.Color.Black);

                //go through images and draw it on the final image
                int offset = 0;
                g.DrawImage(pictureBoxBackground1.Image, new System.Drawing.Rectangle(offset, 0, Image1.Width, Image1.Height));
                offset += Image1.Width;
                g.DrawImage(pictureBoxBackground2.Image, new System.Drawing.Rectangle(offset, 0, Image2.Width, Image2.Height));

                var eps = new EncoderParameters(1);
                eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
                var ici = GetEncoderInfo("image/jpeg");
                finalImage.Save(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + @"\TestImage.jpg", ici, eps);
            }

I’ve also tried to save the picture uncompressed, but that only makes file file bigger and not the quality better.
Thank you in advance!

Answer 1

I have used this GetEncoder method:

private ImageCodecInfo GetEncoder(ImageFormat format)
{
    ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();

    foreach (ImageCodecInfo codec in codecs)
    {
        if (codec.FormatID == format.Guid)
        {
            return codec;
        }
    }
    return null;
}

Invoked it with GetEncoder(ImageFormat.Jpeg); and removed the references to pictureBoxBackground1&2 (otherwise it won’t build) and the end result is high quality as far as I can tell.