Praise be to Allah.
This ruling needs to be divided into categories. If he is developing pictures which people need for necessary reasons or for some reason which will serve the general interest, then it is permissible to develop these pictures and take that as a profession and a source of income, because whatever is permitted for reasons of necessity or serving the common interest, it is permissible to deal in it in all kinds of transactions and contracts. What is permitted in essence for reasons of necessity, it is also permitted to take its price. This kind of pictures and the cameras and machines used for them are a means of serving a necessary purpose which people need, and the means are subject to the same rulings as the ends, provided that this is only done as much as is necessary and as is needed to serve those needs and achieve that interest only, based on the principle “actions based on necessity should measued by that necessity.”
The second type of pictures are those for which there is no need and which do not serve any purpose. The most correct view concerning these pictures is that they are haraam and that it is not permissible to keep these pictures. Therefore it is haraam to develop these pictures.
See Ahkaam al-Tasweer by Muhammad Waasil, p. 602.
See also the answer to Question # 3243 concerning the earnings of one who makes images. And Allaah knows best.