Convert raw RGB32 file to JPEG or PNG using FFmpeg

Use the rawvideo demuxer:

ffmpeg -f rawvideo -pixel_format rgba -video_size 320x240 -i input.raw output.png

Since there is no header specifying the assumed video parameters you must specify them, as shown above, in order to be able to decode the data correctly.

See ffmpeg -pix_fmts for a list of supported input pixel formats which may help you choose the appropriate -pixel_format.