The story behind Princess Charlotte's 9th birthday portrait — and was it Photoshopped?

"Happy 9th Birthday, Princess Charlotte! 🎂 Thank you for all of the kind messages today," the Prince and Princess of Wales captioned the image that was shared Thursday.

The photo was taken by Middleton, who recently came under fire for doctoring an image of her and her children shared on UK Mother's Day on March 10.

According to an expert, there are three reasons why Charlotte's snapshot appears to be unedited — natural colors, no flash and "no harsh shadows."

"It's shot in daylight, not with flash," London photographer Glenn Gratton explained to the Daily Mail, calling it a "lovely, natural picture."

He also noted that the color "hasn't been bleached" and is "exactly what you want from a portrait."

"She's a good, competent photographer who likes to take pictures of her family," he added of Middleton. "And you can see that Charlotte's nice and relaxed. Some children get a little shy posing around their parents, but she's really relaxed and really natural."

Additionally, he said it was a "good follow-up" to Middleton's latest photo of Prince Louis, which she shared last week for his sixth birthday.

Charlotte's snapshot also appears to be a nod to the late Queen Elizabeth II, whom she's named after. (She was christened Charlotte Elizabeth Diana.)

The princess poses alongside pale pink Clematis Elizabeth flowers, one of the first plants to be named after the late monarch.

Middleton, who revealed in March she was diagnosed with cancer, has described herself as an amateur photographer. When she's shared photographs of her children — Charlotte and Louis' big brother is Prince George, 10 — she's often been credited as the one behind the lens.

What has been different, however, is the release times of the portraits. And it's a bit unclear as to why there's been a change.

Kensington Palace usually releases portraits of the Wales children at midnight to mark their birthdays. However, both Charlotte's and Louis' photos were delayed this year.

Middleton has been spending much time with her family since revealing her health condition to the world. As The Post previously reported, she and William had a "difficult" conversation with George and Charlotte about the news, while they "sugarcoated" it to Louis.

"I'm sure it was a very difficult and very different conversation between children," Grant Harrold, who worked for now-King Charles for seven years when he was the Prince of Wales, exclusively told The Post.

"For instance, for Louis, I'm sure the conversation was more sugarcoated than it was with George and Charlotte."

"The older children can understand more, so I'd imagine it was a little more frank, but undoubtedly staying positive, which is so important," Harrold explained.

He added: "I'm sure the children will be handling it as any kids would be expected to handle it, but I think their parents are very good at being calm and collected, and I think that will rub off on the children."