\begin{table}%t1 \caption{\label{Tab}Median colours with 1$\sigma$ standard deviation in the colour distribution for different morphological classes.} \vspace*{-1.5mm} \par %\centering \par {\scriptsize \begin{tabular}{c@{}cccccc} \hline \hline \noalign{\smallskip} Type & $f60/f100$ & $f250/f350$ & $f350/f500$ & $f25/f250$ & $f100/f250$ & $f60/f500$ \\ \hline E-S0a\tablefootmark{1} & 0.37 $\pm$ 0.06 & 2.60 $\pm$ 0.38 & 3.13 $\pm$ 0.39 & 0.09 $\pm$ 0.01 & 1.82$\pm$0.73 & 5.69 $\pm$ 2.96\\ Sa-Sb\tablefootmark{2} & 0.34 $\pm$ 0.12 & 2.50 $\pm$ 0.24 & 2.86 $\pm$ 0.22 & 0.08 $\pm$ 0.09 & 1.10 $\pm$ 0.42 & 3.14 $\pm$ 2.66\\ Sbc-Scd & 0.43 $\pm$ 0.10 & 2.29 $\pm$ 0.40 & 2.70 $\pm$ 0.44 & 0.08 $\pm$ 0.04 & 1.21 $\pm$ 0.45 & 3.66 $\pm$ 2.60\\ Sd-Irr & 0.54 $\pm$ 0.23 & 2.54 $\pm$ 0.35 & 2.97 $\pm$ 0.35 & 0.24 $\pm$ 0.24 & 1.84 $\pm$ 0.63 &10.30 $\pm$ 9.07\\ \hline \end{tabular}} \vspace*{-2mm} \tablefoot {\tablefoottext{1}{Excluding the synchrotron-dominated M~84 and M~87;} \tablefoottext{2}{excluding the starburst NGC 4491.}} \vspace{-2mm} \end{table}