Tautomerization of D-dopachrome with decarboxylation to give 5,6-dihydroxyindole (DHI). {ECO:0000269|PubMed:8267597, ECO:0000269|PubMed:9480844}. This is the function of Ensembl gene identifier ENSG00000099977 (DDT, D-dopachrome tautomerase).