Quality of rendered PDF is not good

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   Hello,
we use the quickpdf library to display pdfs on the screen (.net application).
For some pdfs (they are coming from a scanner) the quality is really bad (with acrobat Reader the PDF is okay). 
Which possibility we have to make the quality better?

We use this code:

Bitmap DrawPdfPage(int page, int width, int height)
        {
            var pw = pdf.PageWidth() / 72.0;
            var ph = pdf.PageHeight() / 72.0;

            int renderDpi = 72;
            renderDpi = (int)Math.Min(width / pw, height / ph); // fit both
            //renderDpi = (int)(width / pw);
            //renderDpi = (int)(height / ph);
            width = (int)(renderDpi * pw);
            height = (int)(renderDpi * ph);

            Bitmap bitmap = new Bitmap(width, height);

            if (page > 0 && page <= pdf.PageCount())
            {
                using (var g = Graphics.FromImage(bitmap))
                {
                    IntPtr dc = g.GetHdc();
                    pdf.RenderPageToDC(renderDpi, page, dc);
                    g.ReleaseHdc(dc);
                }
            }

            return bitmap;
        }

Best regards

Hansjoerg

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
hansjoergp Members Profile Find Members Posts Beginner Joined: 11 Sep 13 Status: Offline Points: 3	Post Options Post Reply Quote hansjoergp Report Post Thanks(0) Quote Reply Topic: Quality of rendered PDF is not good Posted: 11 Sep 13 at 9:16AM
	Hello, we use the quickpdf library to display pdfs on the screen (.net application). For some pdfs (they are coming from a scanner) the quality is really bad (with acrobat Reader the PDF is okay). Which possibility we have to make the quality better? We use this code: Bitmap DrawPdfPage(int page, int width, int height) { var pw = pdf.PageWidth() / 72.0; var ph = pdf.PageHeight() / 72.0; int renderDpi = 72; renderDpi = (int)Math.Min(width / pw, height / ph); // fit both //renderDpi = (int)(width / pw); //renderDpi = (int)(height / ph); width = (int)(renderDpi * pw); height = (int)(renderDpi * ph); Bitmap bitmap = new Bitmap(width, height); if (page > 0 && page <= pdf.PageCount()) { using (var g = Graphics.FromImage(bitmap)) { IntPtr dc = g.GetHdc(); pdf.RenderPageToDC(renderDpi, page, dc); g.ReleaseHdc(dc); } } return bitmap; } Best regards Hansjoerg

AndrewC Members Profile Find Members Posts Moderator Group Joined: 08 Dec 10 Location: Geelong, Aust Status: Offline Points: 841	Post Options Post Reply Quote AndrewC Report Post Thanks(0) Quote Reply Posted: 12 Sep 13 at 10:59AM
	Hansjoerg, Can you try adding the following line to you program somewhere after QP.UnlockKey. QP.SetGDIPlusOptions(3, 1); // Turn on image smoothing Andrew.

hansjoergp Members Profile Find Members Posts Beginner Joined: 11 Sep 13 Status: Offline Points: 3	Post Options Post Reply Quote hansjoergp Report Post Thanks(0) Quote Reply Posted: 16 Sep 13 at 7:56AM
	Thanks it works