Image-to-ASCII generators are certainly not a new idea, so why another? Basically I found all of the online converter sites output some pretty ugly results (and in most cases, processed your image on a remote server) while the tools I saw that are capable of nice-looking results require local installation of varying extents. Plus a few other minor quibbles.
PLaying around with the problem, I found as it turns out we can generate pretty great-looking plain ascii (no Unicode) art completely in the local browser instance with a completely unscientific RGB to character mapping, and then further if the browser is to be the ultimate display for our output, with some pretty-arbitrary choices in CSS tweaking, we get some amazing color results.
Quick and dirty as it is, it definitely works, with results better than I expected to achieve.
Introducing MAGICBIFF - Multi-color Ascii GraphICs from Binary Image File Formats
Upload any type of image file of any reasonable** size.
- The file is "uploaded" only within your browser via javascript into the already loaded page context. It does not leave your machine and is not processed by a remote server; all work is done locally on your computer.
- zooming with ctrl-+ and pinch/stretch on a trackpad scale the image differently; try both ways.
- Sorry, but it doesn't work on mobile devices and I haven't bothered to learn why so I can correct it. (it's still a little glitchy on mobile, but it does work now.)
**reasonable is whatever you deem it to be; it's your computer
  note that the process will greatly reduce the resolution of your image as needed to prevent your browser from crashing, yet the results are still quite pleasing and impressive.