In order to reduce the influence of illumination changes on the appearance of smart meter and improve the accuracy of smart meter appearance detection, based on the local two value algorithm theory, the algorithm is improved as the local two value algorithm of the rotation invariance. But rotation invariant local value operator with the sampling number of blocks increases the operator types will be a substantial increase, this limitation is bound to increase computing influence quantity calculation speed. Therefore, it will be done in a unified process, and the unified local two value algorithm is obtained. In the light of the smart meter in strong lighting and weak lighting condition, separately use the local two value algorithm theory and the unified local two value algorithm are separately used to detect the appearance of the smart meter. The analysis results show that the unified local two value algorithm can recognize the information of the smart meter, which has a certain application value for the smart meter.