Hi Pegaso,
Thank you for your interest in Essential PDF.
Drawing image in center of the PDF documentI was able to reproduce the issue which you mentioned here. Kindly refer the modified code snippet,
PdfImage Img = PdfBitmap.FromFile(images[i]);
x = (doc.Pages[i].Graphics.ClientSize.Width) / 2;
float imgw = Img.Width / 2 ;
PointF location = new PointF(x - imgw, _lastLineY + 20);
SizeF size = new SizeF(Img.Width, Img.Height);
RectangleF rect = new RectangleF(location, size);
doc.Pages[i].Graphics.DrawImage(Img, rect);
Please do find the sample from the below specified location and let me know if this helps,
http://files.syncfusion.com/samples/PDF.Windows/PDF_Window_F89455.zipRegards,
Suba