If this is a file type that is NOT supported by MATLAB for reading, then nothing you do will make imread (or whatever file read tool you want) read it. Code needs to know what to expect. No magic exists.
Having said that, there is no reason why you cannot read in this file, however you will need to write code that knows how to read the file. MATLAB can see the file in your directories, regardless of what the extension is. So you will need to write a tool that understands what the file is. Are there headers? If so, then read them in, in the appropriate format, since YOU know what to expect. You might be using tools like fopen, fclose, fgets, fgetl, or perhaps textread.
