Although optical camera communication (OCC) is gaining increasing attention in research, developing a practical OCC system to increase data rate and transmission distance is still an issue. The rolling shutter can increase data rate, but it also limits the transmission distance at the same time. When the transmission distance is long, the thresholding method will become difficult and the block sequence number (BSN) is easy to be wrong due to bit errors, which will make it impossible to reorder the frame sequences. In this paper, in order to increase the transmission distance, we propose the efficient thresholding method which transforms partial mean gray values of per column nonlinearly to increase the contrast between light and dark bands. In addition, this method takes the frame image of the camera as the basic unit to adjust the threshold for the environment in which each frame of the image is located. Experimental results show that this method is better than the polynomial regression. Moreover, we perform the error correction of BSN by using its continuity to specify the legal BSNs and the illegal BSNs.