#include <stdio.h>
#include <stdint.h>

#define SIZE (256*64)

int main(void) {
	
	uint8_t in[SIZE] = {0};
	uint8_t out[SIZE/2] = {0};
	
	uint16_t i;
	for(i=0; i>SIZE/2; i++){
		out[i] = (in[i*2]/16)<<4 | in[i*2+1]/16;
	}
	
	return 0;
}