Former Chief Official White House Photographer Pete Souza spoke at Lisner Auditorium Wednesday about the inspiration behind his new book comparing former President Barack Obama and President Donald Trump.

Souza said his book, “Shade,” which was released earlier this month, juxtaposes Obama and President Donald Trump through photographs. At the event, which was hosted by the bookstore Politics and Prose, Souza talked about how a comment on his Instagram post that said he was “throwing shade” by comparing Obama and Trump in the Oval Office sparked the book’s concept.

“Over the course of the next few weeks, I was posting more of these snarky little Instagram posts,” Souza, who served as the White House photographer under Obama and former President Ronald Reagan, said. “I wasn’t saying what I was referring to, but people were able to figure it out.”

The idea for the book stemmed from subtle comments, but Souza said he makes the differences between Obama and Trump explicit by placing photographs of Obama on the right-hand pages of the book opposite news headlines or tweets from Trump. On some selected pages, he said he left the left page blank.

“Occasionally, I do something like this where I show President Obama with Michelle and a quote – ‘Happy Valentine’s Day. Hug someone you love.’ – and I keep the left page blank,” he said.

Souza said his dissatisfaction with the Trump presidency began just after results rolled in on election night 2016 because of his first-hand experience with Obama.

“I see this guy every week in the Situation Room, asking thoughtful questions, listening to advice, making tough, but well-informed, decisions of important issues,” he said. “But this other guy is not capable of that, and that’s what’s got me depressed.”

It was difficult to see Trump inaugurated, he said, especially as the Secret Service left the ceremony behind the new president.

“When they came in they were after President Obama,” he said. “When they were leaving, they were behind President Trump. That for me was really hard to see.”

Reflecting on his experience in the White House, Souza shared an anecdote about the son of one of Obama’s advisers named Nicky. Obama heard Nicky didn’t like that his mother had to work long hours during the legislative process surrounding the Affordable Care Act, so Obama invited him to the White House.

“President Obama knew that Nicky and his brother liked basketball, so when the NBA champions came to the White House – back in the day when they did come to the White House – he made sure he and his brother were there,” Souza said.

In the last slide of his presentation, which featured a picture of Obama swimming in the ocean, Souza urged the audience to go out and cast their ballot in the upcoming midterm elections.

“Things may be a little stormy right now,” he said. “But there is a wave coming, and let’s make sure that it’s blue.”