The picture is Felicity's dirty little secret.
He doesn't take pictures.
Doesn't like them. Cameras invade every other aspect of his life. He'd rather they not be present in the parts, he doesn't let the world see. Except for one picture, and only because he doesn't know about it. She remembers the day she took the picture. It had been the first fourth of July after they got married and everyone had shown up - Dig and Lyla, Thea had come with Roy close behind, and even Ray had made an appearance.
He had been relaxed and pleasantly social, dressed casually in a navy blue T-shirt, and a pair of shorts, with a beer in his hand and a smile pulling at the corners of his mouth.
(The delicious neckline of that t-shirt had been responsible for its destruction later that night. After which, Felicity had to confess to her chest fetish.)
But, Oliver laughing is different.
Usually - and by usually, she means all the time - his laugh is insincere at best. It's half-assed and sarcastic, mocking even, and more for the sake of show than for anything. But the real thing. The genuine Oliver laugh is music to her ears. It's low and warm and loud and contagious. His laugh is why she'd chosen that moment, that perfect moment when the pretenses were dropped, and his guard was down, to take a picture. When he let his friends see what Starling City never does.
The real Oliver.