p081fig02.35 The equilibrium activities of a shunting netwok with Gaussian on-center off-surround kernels are sensitive to the ratio-contrasts of the input patterns that they process.  The terms in the denominator of the equilibrium activities accomplish this using the shunting on-center and off-surround terms.<BR>||  Ratio-contrast detector.  flat versus [Gaussian Cki, flattened Gaussian? Eki]<BR>d[dt: xi] = -A*xi +(B - xi)*sum[k≠i: Ik]*Cki -(xi + D)*sum[k=1 to n: Ik*Eki]<BR>Cki = C*e^(-μ*(k - i)^2), Eki = E*e^(-μ*(k - i)^2)<BR>At equilibrium: xi = I*sum[k=1 to n: θk*Fki] / (A + I*sum[k=1 to n: θk*Gki])<BR>Fki = B*Cki -D*Eki (weighted D.O.G)<BR>Gki = Cki +Eki (S,O,G)<UL><LI>Reflectance processing<LI>Contrast normalization<LI>Discount illuminant</ul>