Grazia magazine published a picture of the Duchess in her wedding dress that appeared to make her look thinner, according to the complaint the PCC received.
The PCC is a self-regulatory industry body that deals with complaints about content in newspapers and magazines. Currently the rules governing press behaviour in the UK are set out by editors in a code of practice. The Editors' Code is a set of standards publications should observe when reporting and includes rules on accuracy, intrusion into grief and privacy and secret recordings.
The PCC can 'name and shame' publications that break the Editors' Code and ask them to publish apologies, but it has no legal powers to enforce punishments such as fines for violations of the Code.
The Editors' Code states that the press "must take care not to publish inaccurate, misleading or distorted information, including pictures". Significant inaccuracies must be corrected and apologies published as appropriate. The PCC should agree on the prominence of the apologies in cases they are involved in, the Editors' Code states.
Grazia made the Duchess appear thinner when it altered the image of her to remove Prince William from the picture, according to the PCC.
"The magazine explained how the image had been altered to remove the arm of Prince William so that the Duchess could be featured on the cover alone," the PCC said in a statement.
"This involved mirroring one of the Duchess's arms and an inadvertent result of the change was the slimming of her waist," the statement said.
Grazia issued an apology, which it negotiated with the PCC. It said the work was done by its "reproduction house" and was not done with the intention of making the Duchess look thinner.
"We wanted a great image of the Duchess on her own, but all the photographs had the Duke in too. So we asked our reproduction house to remove him from the picture (common practice among glossy magazines)." Grazia's apology said, according to the PCC.
"This would have left the Duchess with only one arm, so they copied over her arm to complete the picture. We would like to reassure all our readers that we did not purposely make any alterations to the Duchess of Cambridge's image to make her appear slimmer, and we are sorry if this process gave that impression. Grazia takes the issue of women's body image very seriously and we would never 'slim down' a picture of a female role model," the magazine said, according to the PCC.