Left: r-band image of the central region of NGC 4104. The contours correspond to surface brightness from 19 to 22 mag arcsec⁻² and the yellow bars give the linear scale length. Right: g − r color image of the same region, with the same contours. There is a faint linear structure crossing the image perpendicular to the major axis with a distinctive red colour. Each panel covers an area of kpc².