Is it obligatory to make up a day of Ramadan fasting for someone from whom semen was discharged due to repeatedly looking at a picture, given their ignorance that this might necessitate breaking the fast?

A Muslim must lower their gaze from what is unlawful to look at, especially during Ramadan (definition). If one intentionally looks at forbidden scenes, they are sinful, and their fast is invalidated if semen is discharged with their knowledge of it. However, if they did not intentionally look, or if pre-seminal fluid (madhy) was discharged, the fast is not invalidated. They must repent and not return to such a forbidden act.