How to convert JPEG image from PNG image and draw those JPEG image into PDF document?

public Stream ConvertPngToJpeg(Stream stream)
{
        //Convert image stream into byte array
        byte[] image = new byte[stream.Length];
        stream.Read(image, 0, image.Length);
 
        //Load the bitmap
        Bitmap resultBitmap = BitmapFactory.DecodeByteArray(image, 0, image.Length);
 
        //Create memory stream
        MemoryStream outStream = new MemoryStream();
 
        //Save the image as Jpeg
        resultBitmap.Compress(Bitmap.CompressFormat.Jpeg, 100, outStream);
 
        //Return the Jpeg image as stream
        return outStream;
 }

Stream ISave.ConvertPngToJpeg(Stream stream)
{
       //Convert image stream into byte array
       byte[] image = new byte[stream.Length];
       stream.Read(image, 0, image.Length);
 
       //Load the image
       UIKit.UIImage images = new UIImage(Foundation.NSData.FromArray(image));
 
        //Save the image as Jpeg
        byte[] bytes = images.AsJPEG(100).ToArray();
 
        //Store the byte array into memory stream
        Stream imgStream = new MemoryStream(bytes);
 
        //Return the Jpeg image as stream
        return imgStream;
}

public async Task<Stream> ConvertPngToJpeg2(Stream s)
{
         byte[] resultArray = null;
            
         //Convert stream into byte array
         byte[] image = new byte[s.Length];
         s.Read(image, 0, image.Length);
           
         //Create An Instance of WriteableBitmap object  
         WriteableBitmap resultBitmap = new WriteableBitmap(1, 1);
 
         using (IRandomAccessStream ms = new InMemoryRandomAccessStream())
          {
              await ms.WriteAsync(image.AsBuffer());
              ms.Seek(0);
                
               //Set the source for WriteableBitmap  
               resultBitmap.SetSource(ms);
          }
 
        //Get the image data
        using (IRandomAccessStream ms = new InMemoryRandomAccessStream())
         {
             try
              {
                  byte[] bytes;
 
                  // Open a stream to copy the image contents to the WriteableBitmap's pixel buffer
                  using (Stream stream = resultBitmap.PixelBuffer.AsStream())
                  {
                      bytes = new byte[(uint)stream.Length];
                      await stream.ReadAsync(bytes, 0, bytes.Length);
                  }
 
                 // Create an encoder with the Jpeg format
                 BitmapEncoder encoder = await   BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, ms);
                   
                 // WriteableBitmap uses BGRA format 
                 encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)resultBitmap.PixelWidth, (uint)resultBitmap.PixelHeight, 96, 96, bytes);
 
                 //Terminate the encoder bytes
                 await encoder.FlushAsync();
                    
                 resultArray = new byte[ms.AsStream().Length];
                 await ms.AsStream().ReadAsync(resultArray, 0, resultArray.Length);
             }
             catch (Exception e)
             {
                  System.Diagnostics.Debug.WriteLine(e.Message);
             }
         }
 
         //Store the image into memory stream
         Stream imgStream = new MemoryStream(resultArray);
 
        //Return the Jpeg image as stream
        return imgStream;
 }

//Load the file as stream
Stream docStream = typeof(App).GetTypeInfo().Assembly.GetManifestResourceStream("ImageDrawing.Assets.Sample.pdf");
 
//Load a PDF document.
PdfLoadedDocument doc = new PdfLoadedDocument(docStream);
 
//Get first page from document
PdfLoadedPage page = doc.Pages[0] as PdfLoadedPage;
 
//Create PDF graphics for the page
PdfGraphics graphics = page.Graphics;
 
//Load the image
Stream imageStream = typeof(App).GetTypeInfo().Assembly.GetManifestResourceStream("ImageDrawing.Assets.logo.png");
 
Stream stream = DependencyService.Get<ISave>().ConvertPngToJpeg(imageStream);
 
//Load the image from the stream
PdfBitmap image = new PdfBitmap(stream);
 
//Draw the image
graphics.DrawImage(image, 0, 0);
 
MemoryStream memoryStream = new MemoryStream();
 
//Save the document into memory stream
doc.Save(memoryStream);
 
//close the documents
doc.Close(true);
 
//Save the stream into pdf file
DependencyService.Get<ISave>().SaveAsync("sample.pdf", "application/pdf", memoryStream);