[Tex/LaTex] How Equation label in \begin{cases}


I would like to present the below equation using equation numbers. But it does not show it in the pdf file. Has anybody an idea? Thanks

\[ \varphi(x,y) =
\begin{cases} \label{ch:five:sec:5:eq4:1}
      1 & if \quad |I(x,y) - \overline{I(x,y)}|> JND_{ST}(x,y), \\
      0 & \quad \quad \quad otherwise \\

Best Answer

It's not \label that generates the equation number: use the equation environment instead.



\varphi(x,y) =
      1 & \text{if $|I(x,y) - \overline{I(x,y)}|> \mathit{JND}_{\mathrm{ST}}(x,y)$}, \\
      0 & \text{otherwise}


enter image description here