Gerard Baden-Clay Mr Baden-Clay's lawyers say he is devastated and will vigorously defend the charge. — ABC Online, 13 June, 2012

The ABC's lawyers insisted on pixelating Mr Baden-Clay's image after he was charged with murder, when many other media outlets didn't. But if you sincerely want to protect someone's identity, that device won't wash any more.

Welcome to Media Watch, I'm Jonathan Holmes.

First tonight, an issue that is going to force media companies in Australia, and perhaps worldwide, to change the way they do things.

About a year ago, Google introduced a new feature to their desktop search engine. They called it Search by Image. And it sounded harmless enough...

Wouldn't it be great if you could use an image to start your search on Google? Now you can, with Search by Image. Whether your image is from the web, or your last vacation. You can search places, art, and even mysterious creatures, by just one picture. —google.com/insidesearch

Basically, you just drag an image from the web, drop it into Google Images, and it will do its best to identify it. And its best is very good indeed.

When the tool first came out, a few people pointed out how these reverse image search engines - and Google's isn't the only one - could be useful to journalists.

For example, Briton Paul Bradshaw in his

ONLINE JOURNALISM BLOG The service should be particularly useful to journalists seeking to verify or debunk images they're not sure about. — Online Journalism Blog, 15th June, 2011

Read Paul Bradshaw's blog

Bradshaw gave this example:

OSAMA BIN LADEN IS DEAD — Online Journalism Blog, 2nd May, 2011

This gruesome image was used by many mainstream media outlets on the day Bin Laden was killed. But, said Bradshaw...

It took me all of 10 seconds to verify that it is a fake - by using TinEye to find other instances of the image, — Not the Online Journalism Blog, 2nd May, 2011

Read Paul Bradshaw's blog

Tin Eye is another reverse image search engine - but it's nothing like as widely used as Google, and it's not as powerful either.

And because of that, Google's Search by Image has a much more serious downside for the media: it makes this convention almost meaningless...

Australian man Paul 'Doug' Peters arrested...over Madeleine Pulver collar bomb hoax — Telegraph Online, 16th August, 2011

That was in Sydney's Daily Telegraph last August. This was in the Sydney Morning Herald...

Arrested...Paul "Doug" Peters. The image has been pixelated for legal reasons. — Sydney Morning Herald, 16th August, 2011

A bit of a formality. Peters's image had been all over the papers for days.

But he'd just been charged, so to publish his picture from then until his trial might have been in contempt of court.

But anyone who wanted to could have taken either of those online stories... clicked on the image...dragged it into Google Images...and up would have popped numerous unpixelated images of Peters, complete with texts identifying him.

In that example, the media were doing the minimum to stay within the law.

But sometimes they genuinely want to conceal someone's identity.

We were tipped off to this problem by a couple of viewers who'd read a story last week in The Age and the Sydney Morning Herald online.

Both websites published a pixelated image of someone who'd given them information, but who didn't want to be identified.

But it took our tipsters just seconds to find the source's identity using Google's Search by Image.

As one of them said, the informant is...

...not exactly Deep Throat, but it nevertheless seems anyone who has photos online with their real name attached ... ought nowadays think twice before speaking to the media "anonymously" — Media Watch Tipster, 3rd July, 2012

We sent some questions to Darren Burden, National Editor-in-Chief of Metro Fairfax Media. He was alarmed...

This is a search feature which has some serious implications for the digital news industry and pixelation techniques. — Darren Burden, Editor in Chief, Metro Fairfax, 5th July, 2012

Read Darren Burden's response to Media Watch's questions

And in a later email...

I would think that barely any publisher know(s) about this worldwide - it was the first time I had seen this issue. — Darren Burden, Editor in Chief, Metro Fairfax, 6th July, 2012

Google's algorithms are amazingly powerful. Its image search doesn't rely on the metadata - the invisible coded tags that are attached to most images on the web. And it works with very little visual information.

For example, here's a heavily pixelated image of me, stripped of metadata. There's not much background to go on. But Google effortlessly matches it to the picture on the Media Watch website - and up pops my name and biography.

We've tried the technique on pixelated pictures of all kinds of people whom media outlets - including Media Watch - have agreed not to identify.

So long as the same or a similar picture has appeared somewhere on the publicly-accessible internet before, Google will find it, along with any information that might have gone with it.

So what are the consequences for the media? Darren Burden tells us that as far as Fairfax Media is concerned...

Fairfax has added processes to check this, but I wonder how much responsibility Google should also take? — Darren Burden, Editor in Chief, Metro Fairfax, 9th July, 2012

The answer to that, it seems, is none. We asked Google to comment.

Our question was sent to Google HQ in Mountain View, California. And what we got back was regurgitated PR guff

Think about all those vacation photos you have of buildings or monuments whose name you can't remember when you get home... — Google spokesperson, 9th July, 2012

Read Google's response to Media Watch's questions

Gee, that's helpful, isn't it?

The courts and the mainstream media will have to work out what all this means for cases where the law is involved.

But the media is now on notice: if it really wants to conceal someone's identity, it can't just lightly pixelate a picture that's already appeared anywhere on the web.