fid = fopen('TheFile.dat', 'r');
pixels = fread(fid, inf);
fclose(fid);
Image_Array = reshape(pixels, ... some appropriate dimensions ... );
image(Image_Array);
You need to know the shape (rows, columns, number of color channels), or those have to be stored in the file. Watch out for whether the data was stored "across" (fairly common) or "down" (what MATLAB expects.)
