When I was growing up on the prairies in the 50's and 60's there were always photos and postcards around that were hand-coloured or hand-tinted. I liked the effect, even when it was a kitschy travel photo-card from some obscure tourist spot. Maybe especially if it was a kitschy photo-card. I had just started acquiring the coloured pencils and spray-can lacquer to hand-colour photographs when I went digital and now I do it with Photoshop.
Colouringbooks were one of my favorite indoor childhood pastimes. Individually painting in the leaves in a forest shot is a good way for an insomniac photographer to spend the late-night hours.