Multiband analysis of a sample of blue compact dwarf galaxies. I. Surface brightness distribution, morphology, and structural parameters

Broadband observations in B, V, R, and I have been performed for a sample o f 28 galaxies cataloged as blue compact dwarf galaxies (BCDs). Our deep ima ging, reaching surface brightness levels of a few percent of the sky bright ness, has allowed the detection of underlying emission or low surface brigh tness features for a substantial fraction of the sample. In this paper we p resent the first results of the program: deep contour maps in the B band, s urface brightness profiles, and color profiles for all the galaxies. The in formation derived for this sample of galaxies has allowed us to analyze the morphology and the structural components of BCDs. Over 70% of the galaxies show complex profiles that preclude fitting by a single standard law, with extra structure at high to intermediate intensity levels. In 21 galaxies o f the sample, an underlying low surface brightness component has been detec ted.