Macro putByte 

macro_rules! putByte {
    ($val:ident,$key:ident,$typ:ident,$slf:ident.$($x:ident).+) => { ... };
}

Parse a hex string containing one byte and put value into the image using the given key path.

putByte!(val:&str,key_path:&Vec<String>,image_type:String,self.path.to.byte:u8)