It would be nice if TIF, PNG, and JPG images could be opened.
The algorithm appears to operate on data after demosaicing. If so, raw information isn't strictly necessary.
There are open issues related to DNG files (#36, #60, #70). The ability to work on TIF files could serve as a workaround until those issue can be resolved directly.
The old command-line filmulator was able to process TIF and JPG images.
It would be nice if TIF, PNG, and JPG images could be opened.