Sean Heavey recognised his photo the moment he saw it on Stranger Things.
“God, that storm looks familiar,” he said, as he and his son watched the hit Netflix show.
When he watched a documentary about the making of the series, he became certain.
“They saved it off of Google, added a foreground to it and used it as a piece of concept art,” Mr Heavey says.
No-one else had photographed this supercell thunderstorm; no other cars drove down the road that day, to chase it across the Montana prairie.
He called the four panoramic shots he had stitched together The Mothership.
“I should have got credit and paid for it,” says Mr Heavey.
He tried to contact Netflix, but the company told him, “You can't copyright Mother Nature.” His case stalled.
Chasing storms is no hobby for Mr Heavey.
Getting that perfect shot costs him thousands of dollars in petrol every year. He braves “golf ball-sized hail”, winds raging over 100mph and rescues stranded people.
He complained on social media and his remarks were read by executives at Pixsy, a firm that helps photographers fight copyright infringement. They contacted Mr Heavey and, eager for the help, he agreed to work with them.
Pixsy appointed Mr Heavey a lawyer, David Deal, and together they found six more occasions where Netflix used The Mothership. Netflix settled the lawsuit in December 2018, according to records seen by the BBC.
The company did not respond to a request for comment.
In the UK, if convicted in a magistrates' court of copyright infringement you could face six months in jail or a fine of up to £50,000. Conviction in a Crown Court could carry a penalty of 10 years in jail and/or an unlimited fine.
In the United States, fines can reach $150,000 (£115,000) every time a picture is used the wrong way.
When a case is successful, firms like Pixsy collect 50% of the settlement or award at court.
“They all settle,” says Mr Deal, of copyright cases.
He says this is because the law is clear cut.
Pixsy is one of a handful of companies that has developed image look-up technology to monitor and pursue copyright infringement on behalf of photographers.
Its service incorporates artificial intelligence that has been trained to match an artist's work with instances on the web.
It can also identify alterations including crops, re-colouring and layers added or removed.
The moment a picture is taken, as long as it was taken by a human being, it is protected by intellectual property laws.
More than 2.5 billion images are stolen daily, according to a 2019 study by Copytrack, a copyright search and enforcement firm. Many of these are found using a technology called reverse image look-up.
This works like Bing or Google, but rather than using words to find related information, the search matches pictures.
Some of the free image search engines, like TinEye and Google, will also verify when and where a picture was taken and if it was altered.
Copyright infringement firms use this same technology but will also hire a lawyer and cover the costs of filing a lawsuit.
Pixsy is close to filing its 100,000th case of copyright infringement in five years. It currently monitors close to 100 million images.
“Keeping on top of all of this is impossible for any individual. For us, we see this as a very big problem for photo owners and photo creators,” says Kain Jones, the chief executive of Pixsy.
He argues that licence fees are “bread and butter” to many photographers.
“That's where we come in, where we're happy to be the bad guy,” Mr Jones says.
However, Chip Stewart, a media law professor at Texas Christian University in the US, says that because so many of these cases settle out of court, the system is ripe for abuse.
Recently, a student of his used an image from a Creative Commons website for the school newspaper. Though she did not have to pay a licence fee, she did not follow the requirements listed under the photo, to credit the photographer or add a link to his website.
Through Pixsy, the photographer found the student and issued her a letter asking for a $750 licence fee.
“The 20-year-old student was pretty terrified getting a demand letter and she said, 'I thought we did everything right.' And I said, 'I can tell you right now that you didn't, but it's an easy mistake to make.'"
A search through public records revealed that the photographer had filed more than 40 similar cases that year. They negotiated him down and agreed to pay a fee of $500.
Fighting over such a small fee in court would cost a fortune.
“It is not worth two years and tens of thousands of dollars of litigation on the off-chance we might win. And if you lose, you might pay the lawyer fees. That's what these copyright troll firms realise - is that the system is so heavily weighted in favour of copyright owners,” says Mr Stewart.
In response Pixsy said: "One of our key criteria [for Pixsy to work on the case] is that it is a commercial usage of the photo. In your example of the private university, they are a revenue-generating organisation and are not exempt from copyright law. A case would be with the university itself and not an individual student."
Some actors have given those who pursue copyright claims a bad reputation. One particularly prolific lawyer, Richard Liebowitz, has been dubbed a "copyright troll", having filed about 1,280 cases in the Southern District of New York since 2017.
As well as the sheer number of cases he's filed, his behaviour has not endeared him to the courts and a judge recently fined him $103,500 for misconduct, which included "repeated violations of court orders and outright dishonesty, sometimes under oath".
Joe Naylor is the chief executive of ImageRights International, another company like Pixsy that uses technology to help photographers pursue copyright infringement.
He says lawyers like Liebowitz are bad for the industry.
“It does profound and fundamental damage to copyright holders who are trying to protect their rights,” says Mr Naylor.
Pursuing licence fees must always be the photographer’s choice. However, Mr Naylor says his company does not recommend photographers go after non-profit blogs or student newspapers.
While he understands this happens, he says ImageRights International is more interested in defending professional photographers like Sean Heavey.
“There's literally no word that can be spoken to me that makes me more angry than photographers being called trolls for trying to pursue their own claims.”
Sean Heavey still sees instances of The Mothership used without permission.
If people credit the picture he “lets it slide”, especially if there is no profit involved.
Recently he found a lady who was selling prints of the photo claiming it was her picture. Another Instagram influencer often claims The Mothership is his.
He says: “Being able to stand up and know your rights - it's good, because it keeps food on the table for my family.”