Composite image of I Zw 18 and I Zw 18 C with the R, I, and V bands shown in the red, green, and blue channels, respectively. The contours, adapted from P02, are computed from HST WFPC2 R data, after 2D subtraction of the Hα emission (referred to as R′), they thus delineate the morphology of the stellar and nebular continuum emission in the main body of I Zw 18. Contours go from 19 to 25 R′ in steps of 0.5 mag.