How Does Itextsharp?

How does iTextSharp/iText compare to Aspose for creating and manipulating PDF documents?

What is "the original file"? If you are talking about converting some file to PDF and the original file is, say, a large image then the PDF will be bigger because it will contain the image plus a bunch of PDF code. I mean, the converter could compress the image more or something but that would not be what was expected or necessary. "Converting" to PDF won't magically turn a raster image to vector; think of it more as wrapping the raster image rather than converting it. But in general there are lots and lots of ways for PDFs to be large. Old PDF files tend to be rats nests inside. PDF is an old format with decades of version iterations in which over the years the kitchen sink and the kitchen itself were thrown in. A PDF is a stream of various kinds of typed data blobs with a table slapped on somewhere near the end (actually there might be multiple incompatible versions of this table, but I digress). The table maps file locations to data blobs. One of the data blobs is a list of page objects that kicks off the definition of the actual document. As long as the table is accurate to the extent that what needs to be looked up to paint the pages of the document is where the table says it is, the PDF is valid, but you could have junk of arbitrary size everywhere else and it will still open. You could even have megs of well-formed junk, old versions of data blobs and so forth. All of this is valid. Furthermore, commercial PDF readers will handle all kinds of invalid PDFs. T have to because there are tons of malformed PDFs in the wild. Commercial PDF readers will try to repair the table I am talking about if it seems to be broken. T will very rarely just bail out on a screwed up PDF. And many PDF creation programs tend to do weird shit -- I don't know why. I guess, old format plus kitchen sink plus 500 page spec that no one really reads equals lots of weird shit -- which leads to lots of PDFs being mysteriously gigantic but nonetheless apparently valid.