How can you tell if an image has been edited?

By Hannah Ward-Glenton, ITV News Producer

The royals came under scrutiny over the weekend after Kensington Palace released a family photo that appeared to be edited.

The picture, which featured the Princess of Wales with her three children, Prince George, Princess Charlotte and Prince Louis, was released on Mother's Day, but social media users quickly spotted inconsistencies in the image.

Kate then apologised for any "confusion" caused by the picture and said she had edited the picture "like many amateur photographers".

So how can you tell if a photograph has been edited? ITV News explains.

Scrutinise the picture

Lorena Martinez, head of editorial operations in Europe from disinformation tackling company Logically Facts told ITV News how to spot an edited photo, from the basics to a full-on deep dive investigation.

The first thing to do, according to Ms Martinez, is to scrutinise the main elements in the picture and look for anything that doesn't look quite right.

"Zoom in using the magnifying glass and go through the whole picture," Ms Martinez said.

If anything is pixelated or blurry, that can be a sign of something being awry.

The main part of the photo of the Princess of Wales that got noticed by beady-eyed royal watchers - and was the reason photo agencies gave for "killing" the image - was that part of Princess Charlotte's sleeve "was missing and had clearly been altered".

There were also queries over the position and colouring of the zip on Kate's jacket and the blurriness of one of her hands.

The royals were accused of altering an officially-released photo in December on similar grounds after Prince Louis appeared to have more than two legs and looked as though he was missing a finger.

Analyse the background

Once you've looked at the subjects of the photo, the background is the next place to scan for inconsistencies.

Some social media users for example started to look at the tree in background of the royal family picture, as there was a tree covered with green leaves.

Details like this can give hints as to what time of year the photo was taken.

"The background is something that people shouldn't overlook, it should be also analysed and gives you clues, like if the tiles and concrete in the background also didn't align well," Ms Martinez said.

Fake image detectors

As fake images become more widely circulated online, software has been developed to tell an original apart from an edit.

You can upload images to fake image detectors and they can say whether the image has been changed.

But these methods aren't foolproof, Ms Martinez warned.

"These tools are not bulletproof. So all the things that I say here, I wouldn't just take one and say, 'OK, I can just rely on this'.

"A combination of methods gives you the best chance of working out how much a photo has been altered, if at all."

Reverse image search

Reverse image search software can also give a good indication as to how close a photo is to its original if the original has already been circulated online.

It works by matching the uploaded image to others on the internet, so will allow you to directly compare the available pictures.

"This all works well with images that are edited lightly, like things that may have been cropped, resized, coloured," Ms Martinez said.

Examining the metadata

When a picture is taken, a lot of additional data is stored on the file, such as the lens model, the date and the time that it was taken.

If GPS settings were enabled, you may even be able to get the location as to where it was captured and the coordinates.

You can then geolocate the location and compare the image with publicly available footage of what the place should look like.

Digging into the weather

If you want to dig even further into the metadata, you can check the weather in the image with the weather on the exact date and time of the picture.

"For example, in [the royal picture], the skies are blue, it's a sunny day. But if you get the date and time, you can go to the weather apps and check what the weather was at the time on that day," Ms Martinez explains.

"If it tells you that it was raining and it was grey, no sun, it will tell you that something is not right here."

This is the Royal Rota - our weekly podcast about the royal family, with ITV News Royal Editor Chris Ship and Producer Lizzie Robinson.

Rogue shadows

It's easy to remove elements from photos, but the shadows cast by those objects might be missed by somebody editing a photo.

"If you see that the shadow cast by the objects in the image is missing or it doesn't align with the light source of the image, we can tell you that this photo may have been edited," Ms Martinez said.

There are also apps and online tools that you define the angle alignments of the shadows and how they should look depending on your location.

"This is a bit more advanced, but they can help you to see if things have been edited."

Do we need to know if photos have been edited?

The impact of editing a photo is entirely dependent on context, Ms Martinez said.

Most photo editing is just for fun, such as for making memes, but when it comes to public figures there are likely to be more ramifications.

"You may erode the trust of the population ... There could be consequences here because you are trying to mislead the public," Ms Martinez said.

This is particularly relevant as we approach election seasons in the UK, mainland Europe and in the United States, where faked and manipulated imagery is likely to play a more pervasive role than ever before.

Photo editing in itself is not a bad thing, but it is very much dependent on context.

"It's not the same to just make the photo look a bit brighter, as to add someone in the picture who wasn't in the picture," Ms Martinez added.

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