construct a heatmap with matrix by HeatMap

HMobj = HeatMap(alldata,'RowLabels',{'JB1','JB2','JB3','JB4','JB5','JB6','JB7','JB8','JB9'})

 alldata is a 9*253 matrix. Data range is [0 680].

如何修改colorbar 显示的范围呢？