Acrobat not optimized for .png ?

Question

Hi everyone.
I need to convert a 750 kb png file (8bit RGB, no transparency) into a .pdf file, which I have to keep as small as possible.
So I open the .png file in Acrobat and save it as a .pdf
I would have expected a resulting ~770-800 kb .pdf,
however it turned out to be an unsatisfactory 1164 kb.
While I do understand that encapsulating a .png file into a .pdf file will inevitably and inherently increase the file size, but the container alone needs about ~20 kb. So there is something else going on here.
From my observations, I get the impression, that the .png file's binary content is not embedded 1:1 into the .pdf file, but interpreted - meaning that the .png content is decoded into a full resolution bitmap image ... which is then recompressed according to the settings in edit > preferences > categories > convert to pdf > png > edit settings > compression > color
I want the conversion to be lossless, so the only possible options here are "ZIP" and "JPEG2000 (quality:lossless)". But both options invariably lead to the same file size mentioned above (~1164 kb).
So my question is:
Is there ANY way to convert a .png file into a .pdf file by simply embedding the .png content, i.e. without decoding the .png into a bitmap image and recompressing it?
Many thanks!
PS: I am on Acrobat Pro 8, and familiar with all the options in PDF optimizer (which were not capable of substantially reducing the .pdf file size without resorting to lossy image compression)
PPS: I can upload a sample file if need be.

Answer 1

Phillip, I thank you and honestly appreciate your help.
But I went out of my way to provide fairly detailed information about the problem, my objective and what I've already tried so far and you hardly take any of that into account, ignoring specifically that I said I'm "familiar with all the options in PDF optimizer (which were not capable of substantially reducing the .pdf file size without resorting to lossy image compression)". I have already maxed out ALL non-image settings for maximum compressibility. As for the image compression, my OP stresses twice that it needs to be lossless, thus not allowing for the DPI reduction you suggested (which besides is in many cases – including mine – a not so good idea because well compressible PNGs, such as non-photographic imagery, may even end up increasing in file size due to the anti-aliasing involved in the DPI reduction).
My objective and my question highlighted above in yellow still stand. Is there no way to preserve the PNG's bitstream when converting to .pdf? Do I really have to settle for a 200%-1400% increase in file size (as shown by the examples above)?? And more generally speaking: Is Acrobat 8 incapable of using PNG compression for images? If no, how is this possible, given that PNGs have been supported by all major Internet Browsers for more than a decade!
Thank you.
PS: Here is the 129kb .png file from posting #2 in case anyone wants to try a .pdf conversion