RCEU_PDFWorkflowManager/PDFWorkflowManager/PDFWorkflowManager/ImageService.cs

using ImageMagick;
using System.Drawing;
using System.Drawing.Imaging;

namespace PDFWorkflowManager
{
    public static class ImageService
    {
        public static void ConvertToJpeg(string sourceFileName, string destinationFileName, int compressionLevel, int dpi = 300)
        {
            using (Image sourceImage = Image.FromFile(sourceFileName))
            {
                float scaleFactor = dpi / sourceImage.HorizontalResolution;
                int newWidth = (int)(sourceImage.Width * scaleFactor);
                int newHeight = (int)(sourceImage.Height * scaleFactor);

                using (var newImage = new Bitmap(newWidth, newHeight))
                {
                    newImage.SetResolution(dpi, dpi);
                    using (Graphics graphics = Graphics.FromImage(newImage))
                    {
                        graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                        graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        graphics.DrawImage(sourceImage, 0, 0, newWidth, newHeight);
                    }
                    EncoderParameters encoderParameters = new EncoderParameters(1);
                    encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, compressionLevel);
                    ImageCodecInfo jpegCodec = GetEncoderInfo(ImageFormat.Jpeg);
                    newImage.Save(destinationFileName, jpegCodec, encoderParameters);
                }
            }
        }

        public static ImageCodecInfo GetEncoderInfo(ImageFormat format)
        {
            foreach (ImageCodecInfo codec in ImageCodecInfo.GetImageDecoders())
            {
                if (codec.FormatID == format.Guid)
                    return codec;
            }
            return null;
        }

        public static void CreateThumbnail(string fileName, string outputPath)
        {
            using (var image = new MagickImage(fileName))
            {
                var size = new MagickGeometry(240, 340) { IgnoreAspectRatio = false };
                image.Resize(size);
                image.Write(outputPath);
            }
        }
    }
}