7-segment LCD to BCD decoder ?

Just in case any hacker-types here (purists turn away now) Got a bit bogged down with the first stage of extracting 7seg data. Chinese made kit with uC buried under black epoxy.

20 LCD lines wiht nice ATE pads for soldering external wiring to. Decided on cutting and re-making 3 LCD traces , as all segments are lit at POST, to determine the multiplexing structure. 4 backplanes and 16 channel , 4-level drive voltages, for digits and anunciators. 2 channel per digit split vertically into abc,dot / defg In this case to extract the segment on/off data, doubt it is generally applicable though . I'm only interested in 2 digits, so 3x4 matrix of 3 BP (dot , c and d not used) and 4 channels. Used a bridge of 4x4148 and 100nF, then a "pull-up" resistor for the off state, connected lowside rectified DC to supply for each of the 10 monitored pairs. Using the original 3.3V supply and feeding the floating quasi-DC low and high to 4070 exor gate inputs of one gate per digit, the low-DC side off state needs pulling high to give reliable Exor "0" output. So LH for H out,ie "on" and HH for L out,ie "off" Pull up needs to be 100K or higher to avoid disrupting the original LCD display, underlying uC operation unaffected. Now to progress to original query placed here, as at the moment just 2 simple unmultiplexed 7 segment LED displays reading the same as 2 LCD digits (ignoring c and d and dot segments)