Three-color image of I Zw 18 displaying the unresolved stellar emission (I_d) in the red channel and the R and V emission of compact ne-dominated regions in the green and blue channels. White areas in the central (red) part of the galaxy depict regions whose colors are strongly affected by nebular emission, as is apparent from their extremely blue V − I and R − I (<–0.4 ...–0.8) colors. The inset, showing a magnified portion of the western supershell, is meant to illustrate a subtle spatial shift between the V_c and R_c emission. This can be attributed to a spatial displacement by 30–100 pc between the intensity maxima of the [Oiii]λλ4959, 5007 and Hα emission lines.