Blurry effect when converting to image

Thank you for your support.

I have converted ar002.pptx to image using Aspose.Slides 17.11. Please find error(no blurry) in 1.jpg.
ar002.zip (22.7 KB)
1.jpg (6.9 KB)

I have also attached ar002.tif which is a tif MS PowerPoint outputs as a reference.
ar002.tif.zip (19.5 KB)

This is my code.

public static List ConvertPowerPointToImage(string docName, MemoryStream docStream, Dictionary<string, string> config)
{
try
{
var pageInfoList = new List();

        // Get config setting
        string docRootDir = config["DocumentsFilePath"];
        int dpi = int.Parse(config["ImageDPI"]);
        int thumbMaxH = int.Parse(config["ThumbnailMaxHeight"]);
        int thumbMaxW = int.Parse(config["ThumbnailMaxWidth"]);
        int maxPageNum = int.Parse(config["DocumentMaxPageNum"]);
        float readScale = float.Parse(config["ImageReadScale"]);

        // Create images directory
        string pageImgDir = docRootDir;
        if (!Directory.Exists(pageImgDir))
            Directory.CreateDirectory(pageImgDir);

        // Get the encoder of JPEG
        ImageCodecInfo jpgEncoder = GetCodecInfo();
        //EncoderParameters encParams = GetEncoderParams();

        EncoderParameters encParams = GetEncoderParams(int.Parse(config["ImageJpegQuality"]));

        // Instantiate the License class
        Aspose.Slides.License license = new Aspose.Slides.License();
        license.SetLicense("Aspose.Total.lic");

        // Convert .doc and .docx file to PDF.
        Presentation presen = new Presentation(docStream);

        for (int i = 0; (i < presen.Slides.Count) && (i < maxPageNum); i++)
        {
            ISlide slide = presen.Slides[i];

            // Export image file
            string imgFile = string.Format("{0}_{1:D8}.jpg",
                    Path.GetFileNameWithoutExtension(docName), i+1);
            string imgPath = Path.Combine(pageImgDir, imgFile);
            string thumbFilename = string.Format(@"{0}_thumb.jpg", Path.GetFileNameWithoutExtension(imgPath));
            string thumbPath = Path.Combine(Path.GetDirectoryName(imgPath), thumbFilename);
            using (Bitmap bitmap = slide.GetThumbnail(readScale, readScale))
            {
                bitmap.SetResolution(dpi, dpi);
                bitmap.Save(imgPath, jpgEncoder, encParams);
            }

            // Add  PageInfo List
            pageInfoList.Add(imgPath);
        }

        // return results with flag of max page limit over
        return pageInfoList;
    }
    finally
    {
    }
}

They are parameters.

        // Get config setting
           Create Appseting key value for async function
           Dictionary<string, string> config = new Dictionary<string, string>();

           config.Add("DocumentsFilePath", outDir);
           config.Add("ImageDPI", "96");
           config.Add("ImageReadScale", "1.25");
           config.Add("ThumbnailMaxHeight", "252");
           config.Add("ThumbnailMaxWidth", "210");
           config.Add("ImageJpegQuality", "80");
           config.Add("DocumentMaxPageNum", "1000");

@PFU.DSOL2,

I have observed the issue shared by you and have been able to reproduce the issue specified. An issue with ID SLIDESNET-39610 has been created in our issue tracking system to further investigate and resolve the issue. This thread has been linked with the issue so that you may be automatically notified once the issue will be fixed.