Is this a positive OPK?

Madison • endometriosis * ovarian cysts * ttc #1
A lot of the OPK'S that I've seen the line has been wayyyyyy darker than the other. But for whatever reason mine never get that dark. I got this one this morning which is the darkest I've got and I've been testing every 4 hours since and it's getting lighter now. CD 16 of 29.