Example of the different images we used to visually detect nebulae. We show zoom-ins of four different areas of the galaxy. For each region, we show on the top the three colour map (same colours as in Fig. 1, bottom panel), in the middle the [O III]λ 5007 and in the bottom the Hα map. The circles highlight the position of nebulae in the final catalogue, with the solid circles showing the position of confirmed PNe and dotted ones showing nebulae classified either as supernova remnants or as compact H II regions. White triangles show the position of the objects identified by DAOFIND, which are, for the most part, spurious detections.