Test Card J
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Test Card J is a test card, an image used to determine the quality of a broadcast television picture. It is an updated version of Test Card F, which was created by BBC engineer George Hersee, and it first appeared in November 1999.
[edit] Differences
The centre picture in Test Card J is a new version of the picture at the centre of Test Card F, rescanned from the original photograph, to make the colours in the image look more accurate. The centre picture was also re-aligned within Test Card J to put the cross on the noughts and crosses board at the exact centre of the screen.
A green square at the top of the screen, which does not appear in Test Card F, is used within Test Card J to facilitate an easier observation of chrominance to luminance delay.
The negative black squares in the left hand step pattern should flash on and off at 1Hz. This is to aid in the detection of frozen digital links.
Today the test card is rarely broadcast. This is due to the onset of 24 hour television. The last known occasion that the card was broadcast on British screens was Monday 23 January 2006, when early morning tests of the BBC's back-up 'Rebroadcast System' (RBS) were carried out on BBC One and BBC Two. This is however an annual occurrence and it is presumed that the test card would reappear during any further RBS tests. Nowadays, BBC 1 often broadcasts The Sign Zone, several signed programmes and a few films or Antiques Roadshow before linking up with BBC News 24; BBC 2 regularly broadcasts BBC Learning Zone late at night, with Ceefax pages during educational holidays and Open University Programmes on weekends. The era of using test cards on BBC thus appears to be over.
