Kate, Britain's Princess of Wales, issued an apology on social media on Monday for "any confusion" caused by an edited photograph which had been issued by her office Kensington Palace the previous day.
Several leading news organisations including Reuters withdrew the picture of Kate, 42, posing with her three children after post-publication analysis showed it did not meet their editorial standards.
"Like many amateur photographers, I do occasionally experiment with editing," the message on X said, signed with a "C" meaning it was sent by Kate. "I wanted to express my apologies for any confusion the family photograph we shared yesterday caused."
In the picture a smiling Kate, 42, was shown posing with her beaming children Princes George and Louis and Princess Charlotte in Windsor, where the family live. Kensington Palace said the photo had been taken by her husband, heir to the throne Prince William, last week.
News agencies including Getty, Reuters, the Associated Press and AFP and the Press Association later withdrew the photograph. Reuters picture editors said part of the sleeve of Kate's daughter's cardigan did not line up properly, suggesting that the image had been altered.
A royal source said Kate had wanted to post an informal picture of her family to mark Mother's Day, which was celebrated in Britain on Sunday, and had made minor adjustments.
Broadcasters with access to the original image said an examination of its metadata showed it had been saved in photo editing software Adobe Photoshop twice on an Apple Mac.
The picture had already attracted huge media attention as it was the first official photograph of Kate since she spent two weeks in hospital after undergoing abdominal surgery in January for a non-cancerous but unspecified condition.
Although her office said she would not return to public duties until after Easter and that she was recovering well, her absence has led to intense speculation about her health on social media in recent weeks.
"Thank you for your kind wishes and continued support over the last two months," Kate wrote in a message which accompanied Sunday's picture.
Kate and William were pictured together on Monday leaving Windsor by car for London. The prince joined other senior royals for a service to mark Commonwealth Day at Westminster Abbey.
Kate travelled to a private appointment as planned, a royal source said, and did not attend the abbey service.
Another absentee was King Charles, 75, who has postponed public appearances while he undergoes treatment for an unspecified form of cancer.
"In recent weeks, I have been most deeply touched by your wonderfully kind and thoughtful good wishes for my health and, in return, can only continue to serve you, to the best of my ability, throughout the Commonwealth," he said in a pre-recorded message played at the service.
(This story has been refiled to fix a typo in the headline)
