Curtis Norville had photographed nine-week-old Romero lying on a playmat.
But as he and his wife Leonie flicked through the images on Curtis's mobile phone, one in particular stood out.
The striking image showed a ghostly white reflection in Romero's left eye. Curtis, a professional photographer, had never seen anything like it before – but he knew it wasn't normal.
So the parents, from Perry Barr, Birmingham, took their son to the family GP, who immediately referred him to Birmingham Children's Hospital – where a consultant delivered the devastating news that a rare eye cancer had caused a large tumour behind the eye and five smaller ones behind his right eye.
"We'd never heard of this condition before. No one in our family had had it. Our world fell apart," Curtis told his local TV news.
Romero was diagnosed with retinoblastoma, a malignant tumour that starts in the retina, the light sensitive lining of the eye. The condition, which is inherited in around two in five cases, affects around 50 children in the UK each year, generally under the age of five. If caught soon enough, the chances of being cured are around 95 per cent.
Romero was immediately started on a course of chemotherapy and has had six-hour sessions every month for the past four months.
The tumour in his left eye has shrunk by a third and the smaller tumours in his other eye have gone following regular laser treatment.
"Romero is responding well to treatment," his dad said.
"He has been very good and the only problem is he wakes up a lot at night because chemotherapy makes babies feed little and often."
Curtis and Leoni are now campaigning to help raise £4million for the hospital's Children's Cancer Centre Appeal.
He added: 'Romero is incredibly resilient. He is very happy, jolly and playful."
Consultant paediatric oncologist Dr Helen Jenkinson said:
We would expect with Romero that he will make a full recovery, we would expect to cure him and I hope that he will have relatively normal vision when he is older. He has continued to grow and thrive throughout his treatment and he looks fantastic now.
"We are delighted with his progress."
"Retinoblastoma: What parents should look out for"
• A white eye - white pupil or white reflection that can be seen in a photograph where the flash has been used.
• An absence of "red eye" in flash photographs.
• A squint - Although a squint can be just that, sometimes it is a symptom of retinoblastoma.
• Red, sore or swollen eye without infection.
• A change in colour to the iris.