no arguments will show help

main.cpp

@@ -34,6 +34,10 @@ int main(int argc, char *argv[]) {
     unsigned int width = DEFAULT_WIDTH;
     unsigned int height = DEFAULT_HEIGHT;
 
+    if ( argc <= 1 ) {
+    	showHelpText();
+    }
+
     for ( int i = 1; i < argc; ++i ) {
     	if ( strcmp(argv[i], "-v") == 0 ) {
     		verbose = 1;