Fix bit_depth option

src/main.cpp

@@ -170,7 +170,7 @@ int main(int argc, char *argv[]) {
                 }}
             else if (strcmp(argv[i], "--bit_depth") == 0 || strcmp(argv[i], "-b") == 0) {
                 bit_depth = atoi(argv[++i]);
-                if (not(bit_depth % 8)) {
+                if (bit_depth % 8) {
                     std::cout << "Error: DEPTH must be a multiple of 8, got " << bit_depth << " instead" << std::endl;
                     return 2;
                 }}