A photograph shared by the Princess of Wales on Mother's Day has sparked a wave of confusion after she admitted it was edited. 

Four international photo agencies withdrew the image taken by Prince William of Princess Catherine and her three children over concerns it had been digitally altered. 

The Princess on Monday (March 11) apologised for editing the picture, which was the first to be shared after her abdominal surgery.

Read more: Princess of Wales apologises for editing family Mother's Day photo

She said in a statement: "Like many amateur photographers, I do occasionally experiment with editing. 

"I wanted to express my apologies for any confusion the family photograph we shared yesterday caused. I hope everyone celebrating had a very happy Mother's Day. C."

The incident has fanned the flames of speculation about the Princess, who has not been seen in public for weeks. 

We spoke to The Herald's photo editor Craig Alexander about what has been changed in the image, why it was tampered with, and what it means for trust in the Royal family and news images more widely. 

Have you looked at the image? What did you think?

The Herald: The photo shared by Catherine, Princess of WalesThe photo shared by Catherine, Princess of Wales (Image: Kensington Palace)

I had a wee look at it on Photoshop, but the worst part of it is down the bottom on Charlotte's arm where you can see the picture's been tampered with, and you can see it on Louis' jumper. When you look at Louis, it's all very blurred. 

If you look at the Princess of Wales' right hand, it's very out of focus. If you look at Prince George's hands, his left hand seems much bigger than his right. But that could be a trick of the camera.

There's something about that whole area that doesn't look quite right. It's hard to put your finger on it.

There's also something quite strange about how all the kids are smiling. In my experience it's hard to get that age group to all do the same thing at the same time.

There's a bit of flash, the Princess, Charlotte and Louis have flash in their eyes but George hasn't, which is a wee bit strange. 

Whoever did this is not good at Photoshop, that's for sure. It's poorly done. They obviously don't have a great talent. 

Why would the image be tampered with?

The Herald: Areas of the image which suggest it has been photoshoppedAreas of the image which suggest it has been photoshopped (Image: Kensington Palace)

Maybe one of the arms wasn't at the right angle. Maybe Charlotte's had her hand down at the side but they wanted it up. I'm not sure why they would have fiddled. 

The Princess' hands were maybe quite dark and she's tried to brighten it up. All parents want to make their kids look good, but it's probably that they didn't like the position of their hands or stance. It's very tricky to get a picture that everybody looks good in. 

It's fine if it's just for a family picture but for an official press image you just wouldn't do it. Maybe one of the kids wasn't there. That's a possibility that could have happened. 

I think they would have known it's wrong to change the image. The Princess is very involved with the Photographic Society. 

What do you think of photo agencies like AP pulling the photo?

You can understand why the agencies would have pulled the image. Because we are relying on them to put trustworthy images. You think of things like Gaza, I'm expecting them to tell any image I see from them is a true image and not been tampered with. 

It would damage their reputation if it out out later and they hadn't pointed it out. 

Is it unusual for them to 'kill' the photo?

It's unusual for this reason. Usually it's to do with copyright but an image that's been tampered with is unusual.  I don't know why they would have put this out thinking it was okay. 

How do you tell if a photo has been tampered with?

If I get sent an image I'm not sure about I would look at it on Photoshop, look at the history of the image and then blow it up and look for signs of tampering. 

I totally understand why anyone ordinary would play with an image, but it's a bit naïve of someone like her to do this. I would consider this a news picture because of the situation around the Princess' health at the moment. I'm sure she realises this was quite an important image. 

Why would the palace allow this photo to be sent out?

We don't know if they knew. It seems strange they would do that, they have complained about pictures being tampered with [by the press] in the past.

There was a photographer dropped from an agency last year for tampering with a photograph taken as part of a pooled news photoshoot by removing a person from the image, therefore changing events.

It seems strange to me they wouldn't have got an official photographer to do this considering the situation, but that's the style of that family now. Usually Princess of Wales takes the pictures. 

Has this photo made you concerned about future royal photos?

There's that old saying, 'never explain everything'. They have made it 100 time worse by trying to put this picture out. 

I would have always trusted a royal picture 100 per cent. But I think probably now I'll always open them up on Photoshop. I'll be much more diligent to make sure there's nothing going on. 

Are you concerned about the future of photo journalism with things like AI?

It's getting harder and harder to tell if something is 100 per cent true. Something that worries me when we move forward is if you wouldn't be able to tell. 

The sort of things I'd be looking for in AI is: does everything add up? The shadows should be consistent, the lighting should be consistent, that's where you can catch it out. 

It's more worrying if we get to this point with warfare. If you can't say 'that's 100 per cent' it changes everything. Which for us as a newspaper it's terrifying. We work on the basis we are a trusted news organisation and we are only putting out accurate information.