Title :
A TV sign image expander with built-in closed caption decoder
Author :
Leelarasmee, Ekachai
Author_Institution :
Dept. of Electr. Eng., Chulalongkorn Univ., Bangkok, Thailand
fDate :
5/1/2005 12:00:00 AM
Abstract :
A low cost TV set top box capable of expanding sign images and decoding closed caption data is described. Its internal architecture mainly consists of video decoder/encoder, 256 Kbytes of video memories, an infrared receiver and an FPGA based video processing unit. The FPGA implements a 27 MHz 8 bits microcontroller, an image expander, an on screen display unit, a 12C interface plus other control logic. The image expander uses a fixed 2×2 bilinear interpolation coupled with a nearest neighborhood input selection to simplify the hardware that allows 9 image scaling factors ranging from 1×1 to 2×2. The sign image that can be expanded is of the maximum size of 128×128 pixels or approximately 1/25 of the entire TV screen. This video processing unit can also decode both Thai and English caption codes inserted in the vertical blanking interval of the incoming composite video signal and display their Thai-English colored fonts in 32×16 dot matrix forms.
Keywords :
field programmable gate arrays; image colour analysis; image enhancement; image processing equipment; image resolution; interpolation; television equipment; video codecs; FPGA; TV set top box; TV sign image expander; bilinear interpolation; microcontroller; nearest neighborhood input selection; screen display unit; video decoder; video encoder; video processing unit; with built-in closed caption decoder; Costs; Decoding; Displays; Field programmable gate arrays; Hardware; Interpolation; Logic; Microcontrollers; Optical receivers; TV;
Journal_Title :
Consumer Electronics, IEEE Transactions on
DOI :
10.1109/TCE.2005.1468019