“Mystery Meat = Any type of processed meat whose source indistinguishable.”
No this post is not really about mystery meat… LOL
It is however, about something like mystery meat. Imagine going into a diner and ordering stew. It arrives you eat it, it is not bad, it filled your stomach even if not gourmet cooking, and you would go back and have it again. A friend asks you what was in it, and all you can answer is ‘mystery meat’. If on the other hand, you went to the market, selected the ingredients, and then took it home, you could make a gourmet dish. This however would take more time, and maybe it is enough to just fill the stomach with unknown stew.
So what does stew have to do with Photography? Well if you are shooting in JPEG rather than raw, your pictures are mystery meat stew. It seems to do the job, but not superbly. JPEG drastically reduces the amount of detailed information in a photo (diner stew). The Red, Green, and Blue Channels of a RAW photo are each 8 to 14 bits of information (i.e. each channel holds between 255 and ~16 000 color values). Each of the however many mega (millions) of pixels has this information. JPEG typically does 3 types of reductions. One is that it examines the photo and takes the top 250 or so most common colors in the photo and maps the whole photo into this reduced color space. This leads to groups of pixels all having the same color value. This then allows for an optimization of storing one pixel and then a count of near by cells that have the same value. You can sometimes see this in low res photos as little square spots of the same color. Then JPEG typically will reduce the pixel count as well (why have 9 pixels of the same value when 1 would do?). The result of all of this is mystery meat, it is usually good enough to satisfy the stomach of Facebook, but it is not good enough to print or make a 3 day soup. If you want fast food with mystery meat that is fine for posting on the web, then choose mystery meat (aka JPEG), but if you want a gourmet meal then shoot with Raw and take the time in the kitchen.
Below is a medium resolution version (all that makes sense on the web) of the whole image.
Here are two blow ups of the above image, one as high res Jpeg, and the other as low res. You choose.