Prince Louis' birthday picture was branded "straightforward and honest" by a photography expert, as Princess Kate is "using better cameras".
On Tuesday, Prince Louis celebrated his sixth birthday, and the Prince and Princess of Wales shared a new picture of the youngster in the afternoon.
Kate, 42, photographed Louis in the garden at Adelaide Cottage and shared it on social media, breaking tradition by not releasing it to the media beforehand.
London-based professional photographer Glenn Gratton explained why the picture was authentic, saying: "If she has done any photoshop, it's very subtle.
Prince Louis was photographed by Princess Kate
Princess of Wales / Getty
"She's clearly more advanced with her photography. Her pictures have improved year by year on."
Glenn pointed out that the young royal's skin tone is natural, with his mother "keeping his skin blemishes".
The photographer added: "He's only six. She's not tried to make him look like a waxwork. Some parents over-filter their children's pictures."
He also remarked that the lighting is natural as it reflects in Louis's eyes, meaning there was no "artificial" set-up.
Prince Louis posed in the garden of Adelaide Cottage
Princess of Wales
Glenn said there are elements in the photo that would have stood out for someone experimenting with Photoshop.
He added: "His feet are a little bit distracting... and his eyes are a little bit dark, so you'd lighten them up."
However, the princess chose to keep the details in.
Glenn continued to tell The Daily Mail: "It's a straightforward, honest picture taken nicely."
Prince Louis photographed on his fourth birthday
Kensington Palace
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Prince Louis celebrating his fifth birthday last year
PAHe claimed Kate likely used a portrait lens to create the blurred background effect.
The photographer added: "Her photography's improving. She's using better cameras."
Princess Kate caused controversy earlier this year when she admitted to "editing" the family picture released on Mother's Day.
The picture was later pulled from major international photo agencies, causing the princess to take to social media to apologise for the "confusion".