nikon - Embedded jpegs in NEF raw files

I open a .NEF image from my Nikon D80 in the Windows Photos app (the modern/"metro" style app). I then zoom in, and it re-renders or something to display higher resolution, but the colours become less saturated, and the contrast decreases slightly. I presume it first opens the embedded jpeg, then draws the NEF file when I zoom in.

What puzzles me the most is that if I open the NEF in Photoshop and save it as a jpeg, the colours and contrast seem to be in between the first and second (zoomed in then out) previews in the Photos app. Interestingly, the Windows Photo Viewer (desktop app) displays the NEF similarly to the 2nd screenshot, but slightly differently.

So my question is this: why the discrepancies? (Apologies for poorly-worded title)

I have attached screenshots (seen in the Photos app) below:

^ The first preview that opens in the Photos app

^ The second (zoomed in then out) preview in the Photos app

^ After converting into a jpeg

Answer

The JPG image embedded in the NEF file is just one way of interpreting the raw information to make a final picture. It is the automatic conversion done in the camera. This is the conversion used to show you what the picture looks like on the monitor in the camera. They have to pick something. Nikon also encrypts the information so that you can't do the same conversion without the decription key.

This in-camera conversion does take the ambient light color into account, so it's usually not too bad, but it is certainly not the single right answer. The automatic process has no idea what parts of the picture are important to you or what you are trying to show.

Some software may do its own default conversion from the raw data, sometimes just because it doesn't do the decryption. In any case, the JPG picture is just meant as a quick basic way to show you the picture, not as your final picture. It therefore doesn't matter what the camera did or what various software programs do. They all fill the purpose of showing you the picture. Beyond that, the JPG picture is irrelevant, as is any other automated preview derived from the raw data. Ultimately you have to decide what you really want and steer the conversion process accordingly.