The optical illusion dress that's divided the internet: Celebrities join fierce debate over whether this frock is white and gold or blue and black... so which colours do YOU see? 

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It is the question that has divided the internet: is this dress white and gold, or blue and black? 

The two-toned frock has sparked a fierce online debate, with users taking to social media to argue over what colours they see.

The picture of the dress was first posted on Tumblr by Caitlin McNeill, a 21-year-old aspiring singer from Scotland, after noticing her friends saw different colours in the photograph. 

The image has become an online sensation, with posts arguing over the dress's original colours - and science behind the debate - being viewed and shared millions of times.

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Internet sensation: This picture of the dress has sparked debate, with viewers disagreeing over the colour

True colours: The dress, made by the company Roman Originals, is in fact blue and black striped

Even celebrities weighed in on the fashion debate, with Kim Kardashian asking her 29.4million Twitter followers to help settle a disagreement between herself and husband Kanye West. 

And the hashtag #TheDress started trending worldwide on Twitter as the debate when global. There have been more than 1 million tweets mentioning the hashtag.

The original photograph of the dress was taken by Cecilia Bleasdale, who bought it for her daughter Grace's upcoming wedding. 

She sent the image to the bride-to-be, who shared it with her groom. They were the first people to disagree over the dress's colours.

But when the bride-to-be posted the picture on Facebook, a disagreement erupted over the colour of the outfit: some said it was white and gold, while others insisted it was blue and black.

The debate was forgotten until Caitlin McNeill, a close friend of Grace and her new husband, Keir Johnston, posted the picture on Tumblr days after the wedding.

Ms McNeill, whose band played at the Scottish ceremony, shared the photograph on a fan page dedicated to talent manager Sarah Weichel, who represents YouTube stars.

That page gave it the exposure that sent the dress into the online stratosphere. 

While the newlyweds enjoy their honeymoon in Jamaica, their families have been shocked by the coverage over the dress.

She said: 'I thought my followers on Tumblr would maybe have a good reaction, but I never would have considered that Taylor Swift and Mindy Kaling would be tweeting about it.'

The 21-year-old said she decided to share the photo after it sparked debate between her group of friends.

'What happened was two of my close friends were actually getting married and the mother of the bride took a photo of the dress to send to her daughter,' she said.

'When my friend showed the dress to her fiancee, they disagreed on the colour. All of our friends disagreed.'

That is when McNeill shared the photo on a Tumblr fan page dedicated to a talent manager Sarah Weichel.

Then, without Weichel even knowing, or promoting the post, it went explosively viral.

Suddenly, everyone, including celebrities, was weighing in on social media about the dress.

The dress led to a debate between Kim Kardashian and husband Kanye West, with the reality star tweeting, 'What colour is that dress? I see white & gold. Kanye sees black & blue, who is colour blind?'

Actress Mindy Kaling also joined the discussion, writing on Twitter: 'IT'S A BLUE AND BLACK DRESS! ARE YOU F***ING KIDDING ME'. 

Her friend and fellow actor BJ Novak replied writing, 'white and gold.' 

Then recent Oscar winner Julianne Moore jumped in, writing to Novak and Kaling; 'what's the matter with u guys, it's white and gold.' 

To that, Novak replied to Moore; 'Thank you!And congratulations on your Oscar, which Mindy thinks is purple and green.'  

Mother of the bride: Cecelia Bleasdale, left in the dress, with daughter Grace Johnston and son-in-law Keir Johnston. Mrs Bleasdale had no idea the photo of her wedding outfit would take the internet by storm

Creating a buzz: Kim Kardashian called on her 29.4million Twitter followers to help settle a disagreement

Star power: Celebrities including Mindy Kaling, B.J. Novak and Oscar-winner Julianne Moore join the debate

'Confused and scared': Taylor Swift told her Twitter followers that the dress is 'obviously blue and black'

Joining in: Justin Bieber was one of the last celebrities to chime with his views on the dress on Twitter 

Taylor Swift wrote; 'I don't understand this odd dress debate and I feel like it's a trick somehow.I'm confused and scared.PS it's OBVIOUSLY BLUE AND BLACK.'   

And Justin Bieber kept his fans happy by telling them that he sees 'blue and black'.

McNeill said that she never expected the post to prompt such a star-studded debate. 

Some celebrities avoided the issue completely, simply declaring that the dress was ugly. 

Model Chrissy Teigen told her 655,000 Twitter followers: 'F*** the dress it's heinous. While Oscar-winner Jared Leto branded it 'fugly'. 

McNeill said she never expected the picture to spark a star-studded debate, explaining that she just thought her followers on Tumblr would have a 'good reaction'. 

Going global: The hashtag #TheDress was trending worldwide on Twitter as millions weighed in on the frock

Photo trickery? One of the many graphics made in response to the dress claims to explains the discrepancy

Great divide: The Ellen Show suggested on Twitter that people will be defined by their stance on the dress

She also added that she would love to meet Taylor Swift - one of the stars who weighed in on the dress. 

Despite the debate, the body-con dress is in fact royal blue with black lace detailing. 

It is made by British clothing company Roman Originals, which offers 'affordable women's clothing and designer ladies fashion,' and can be purchased here. 

There are also white, pink and red options, all with black lace - and the company have hinted they might bring out a white and gold version.

Ian Johnson, of Roman Originals said: We were absolutely ecstatic about the reception of our fabulous blue and black dress.

'We see blue and black but some people in the office see white and gold too, so much so we’re thinking of doing a white and gold version! 

'We sold out within the first 30 minutes of sale and have since restocked all colours and sizes.

The simple scientific answer behind the debate is that it is an optical illusion. 

Objects reflect light at certain wavelengths, or colours, and the human brain determines the colour of an object by taking in its reflected light. 

But this perception can be thrown off balance by the colour of nearby objects. 

As Wired.com points out, a digital analysis of the dress photo shows that one of the spots of black trim is actually orange in the photo.

Thus, people who perceive the surrounding area as dark are likely to see the blue in the dress as white and the black colours as gold. It all just depends on the manner that the brain perceives and processes colour. 

First post: The photo was initially shared by Caitlin McNeill, 21, above, an aspiring singer from Scotland

Even more colours: The dress can also be purchased in white and black or a pink and black combination

Final say: This Twitter post by Adobe explains why viewers can see different colours in the dress

With the photo of the dress, the surrounding colours are so muddled that the brain isn't sure what to make of the dress itself. 

Adobe, the colour experts, also wrote on Twitter that, using their software, the dress is black and blue. 

McNeill was also happy to settle the debate. She said: 'I got to the wedding and the mother was wearing the dress. Obviously it was blue and black.'

The dress, in black and blue, is also for sale on Amazon, and user comments have been just as amusing. 

'This dress made me lose all of my friends and now I am so lonely,' wrote one.

'Where's the white & gold option!? I KNOW IT EXISTS SOMEWHERE IT HAS TO,' said another. 

Kim Kardashian, Grumpy Cat and Timon and Pumba get the meme treatment as Twitter users mock #TheDress

The picture of the two-tone dress has become an online sensation - with internet users taking to social media to argue over whether it is white and gold, or black and blue.

Twitter has been flooded with posts featuring the frock and '#TheDress' has been trending online for hours. 

The hashtag has been mentioned more than 600,000 on the network, according to social media agency We Are Social.

And now the dress has been given the meme treatment, with people creating graphics to mock the internet's fascination with the dress. 

Some feature online superstar 'Grumpy Cat' while another uses Kim Kardashian, who caused her own internet sensation when she 'broke' the internet with her post of her own racy magazine cover.

A number adapt scenes and posters for hit movies and TV shows - with 50 Shades of Grey, Power Rangers and the Lion King all being featured. 

Famous face: One meme features reality TV star Kim Kardashian, who caused an online sensation when she 'broke' the internet with her post of her own racy magazine cover

Disney treatment: This meme adapts a famous line from classic children's film The Lion King

Showdown: One film fan re-imagined the plot for the next installment of the Captain America franchise

Childhood favourite: A number of Twitter users pointed out the widespread confusion the dress could cause

 

Unimpressed... again: Online animal superstar Grumpy Cat makes an appearance in two #TheDress memes

Better together: This tweeter mixes the dress with #LeftShark from Katy Perry's Superbowl performance

To the point: This Twitter user posted a meme that spoke for millions wrestling with #TheDress debate