Radial oxygen abundance gradients in units of dex ﹩R_{25}^{-1}﹩ as a function of disk scale length h_W1 (panel a), morphological T type (panel b), central disk surface brightness in the ﹩W1﹩ band ﹩{{({{{\rm \Sigma}}_{W1}})}_{0}}﹩ (panel c), and disk surface brightness at the optical edge ﹩{{({{{\rm \Sigma}}_{W1}})}_{{{R}_{25}}}}﹩ (panel d).