Test Card F was a test card, an image used to determine the quality of a broadcast television picture, and due to its use on BBC television for more than 30 years when broadcasting was off the air, it is probably the most commonly seen test card in the world. The colour picture shows a girl playing noughts and crosses with a doll, surrounded by various greyscales and colour tests needed to ensure a correct signal. It first appeared in 1967, on BBC TWO.

Practically everything on the card had significance. Along the top are the main colours of white, yellow, cyan, green, magenta, red, blue and black. There are triangles on each of the four sides of the card to check for correct overscanning of the picture. The standard greyscale and frequency response tests are found on either side of the central picture. On the updated Test Card J, the 'X' on the noughts-and-crosses board is an indicator for aligning the centre of the screen. A person was used so it would look obvious if skin colour is wrong. Even the garish colours of the clown had a purpose, according to the BBC, because their juxtaposition is such that a common transmission error called chrominance/luminance delay made the clown's buttons show up white.

Often, the name of the broadcasting channel appeared in the space underneath the letter 'F'. Originally a photographic slide, it was converted to an electronic version in 1984.

The card was developed by BBC engineer George Hersee, who died in 2001 aged 76. The girl in the picture is Carole, one of Hersee's daughters. The clown doll is named Bubbles.

Test Card F is no longer used by the BBC, it was last shown in 1999. Test Card J and Test Card W have replaced it.

See also

• Images of test cards

External links

• Test card special (http://news.bbc.co.uk/1/hi/uk/1282160.stm) (BBC News, 19 April 2001)