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There are a lot of questions out there about how to convert a PDF file to a PNG image, but I'm looking to take a nice sharp PNG file and just basically wrap it or embed it in a PDF file without having it look blurry or fuzzy.

I realize with imagemagic installed I can do a simple conversion like:

convert sample.png sample.pdf

I've also tried a lot of the switches to set the depth, and also the quality setting:

convert -quality 100 sample.png sample.pdf

However the PDF still comes out looking blurry / fuzzy.

Here's a sample image:

http://img406.imageshack.us/img406/6461/picture3mu.png

As a png it's crisp and clean. When I convert it to a PDF, even at the same size it looks blurry:

Picture 4.png http://img803.imageshack.us/img803/9969/picture4at.png

How can I convert PNG to a PDF in high quality?

Try using the -density option. The default resolution is 72 dots per inch. So try something like -density 300.

For reference see -density in the ImageMagick command-line options documentation.

It can be very complicated to get good pdf output from convert. Try img2pdf instead. From the readme:

Lossless conversion of images to PDF without unnecessarily re-encoding JPEG and JPEG2000 files. Thus, no loss of quality and no unnecessary large output file.

To clarify: PDF can embed lossless JPEG 2000 images (and most readers appear to support them). So this conversion is completely lossless:

convert sample.png -quality 0 sample.jp2
img2pdf -o sample.pdf sample.jp2

(Assuming the JP2 delegate is available of course: check identify -list format | grep JP2.)

I am almost certain that what you perceive as a loss of quality in the PDF, is just an effect of your PDF viewer's anti-aliasing feature.

If you use evince to view the PDF, you can see the anti-aliasing feature automatically switched off at a certain zoom (300% in my quick test). You can see that vividly when you keep zooming in - you will notice that at some point, pixels become suddenly clearly visible. That is the point when anti-aliasing must have been switched off to allow precise image inspection.

I think that for png-to-pdf -density parameter should small rather than large. You could try something like convert -quality 100 -density 50

PDF is a vector format (i.e., the file contains a description of lines to draw), while other formats (JPG, PNG) are raster formats (the file describes what color to paint each pixel). If you blow a PDF up, it is still just sharp lines; JPG and PNG show the pixelation.

(OK, OK, I lied. A PDF can also be a raster).

Brian Z above provided the below, which is the correct, fully reversible, and lossless (assuming the convert step is in fact lossless, which I think it is or at least ought to be) way to put png's into a pdf. You are required to convert from png to lossless jp2 in order to be compliant with PDF structure / readers (I think).

$ convert sample.png -quality 0 sample.jp2
$ img2pdf -o sample.pdf sample.jp2

However it is worth noting that you can supply the .png files themselves directly to img2pdf like :

$ img2pdf -o sample.pdf sample-page1.png <sample-page2.png ...>

This will produce the smallest pdf file, and will insert the png's raw hex into objects within the pdf losslessly*.

*The drawback, is this process is not reversible unlike using jp2. The header/footer and and chunk header/footer data has been stripped (which actually makes the files even smaller!) from the png that is inserted leaving only the raw picture data (the metadata that was deleted is integrated into the pdf structure), presumably to "hack" the pdf to display raw png which is technically non-compliant with the container. It displays fine in firefox, and may display fine in all modern readers, but if png is non-compliant with the container then strict readers may not render the raw png data (as they should not expect it / process it correctly).

Here you can find an extremely raw bash script that worked for me to extract and reconstruct the png files with matching hashes to the ones used for input into the pdf. https://github.com/jack4455667788/RebuildRawPNGExtractedFromPDF