Back to results
US 5,499,058 AGranted
Digital color encoder using triangular wave modulation
AssigneeIndustrial Technology Research Institute
InventorsChun-Hsien Horng, Guang-Nan Tzeng
Life of this patent
Estimating the term…
Abstract
This invention provides a digital color encoder for digitizing color video signals. The encoder forms a digitized color video signal using logic function processing of the digitized luminance signal and color difference signals. The encoder provides an output signal equivalent to the luminance signal added to the color difference signals modulated by triangular wave functions and sampled at the sampling frequency. The sampling frequency is eight times the crominance subcarrier frequency. An analog video signal can easily be recovered from the digital video signal because the fundamental frequency of the triangular wave is easily separated from the higher order harmonics.
Claims14
A digital color encoder, comprising:
- red, green, and blue primary color signals having a carrier frequency;
- a luminance signal wherein said luminance signal is equal to 0.299 multiplied by said red primary color signal plus 0.587 multiplied by said green primary color signal plus 0.114 multiplied by said blue primary color signal;
- means for producing a first color difference signal from said luminance signal and said red primary color signal wherein said first color difference signal is equal to said luminance signal divided by 1.14 subtracted from said red primary color signal divided by 1.14;
- means for producing a second color difference signal from said luminance signal and said blue primary color signal wherein said second color difference signal is equal to said luminance signal divided by 2.03 subtracted from said blue primary color signal divided by 2.03;
- a sampling frequency equal to eight times said carrier frequency;
- a sampling period equal to the inverse of said sampling frequency;
- a carrier period equal to the inverse of said carrier frequency wherein each said carrier period contains eight said sampling periods;
- a control signal wherein said control signal is equal to a logical 1 during the first, third, fifth, and seventh sampling period of each said carrier period and a logical 0 during the second, fourth, sixth, and eighth sampling period of each said carrier period;
- an inverse control signal wherein said inverse control signal is equal to a logical 0 during the first, third, fifth, and seventh sampling period of each said carrier period and a logical 1 during the second, fourth, sixth, and eighth sampling period of each said carrier period;
- means for sampling said luminance signal, said first color difference signal, and said second color difference signal at said sampling frequency thereby producing quantized levels of said luminance signal, said first color difference signal and said second color difference signal for each said sampling period;
- means for producing a first intermediate signal wherein said first intermediate signal is equal to said quantized first color difference signal during the first sampling period of each said carrier period, zero during the second, third, and fourth sampling periods of each said carrier period, said quantized first color difference signal multiplied by minus one during the fifth sampling period of each said carrier period, and zero during the sixth, seventh, and eighth sampling periods of each said carrier period;
- means for producing a second intermediate signal wherein said second intermediate signal is equal to said quantized first color difference signal multiplied by one half during the second and eighth sampling periods of each said carrier period, said quantized first color difference signal multiplied by minus one half during the fourth and sixth sampling periods of each said carrier period, and zero during the first, third, fifth, and seventh sampling periods of each said carrier period;
- means for producing a third intermediate signal wherein said third intermediate signal is equal to zero during the first, second, fourth, fifth, sixth, and eighth sampling periods of each said carrier period, said quantized second color difference signal during the third sampling period of each said carrier period, and said quantized second color difference signal multiplied by minus one during the seventh sampling period of each said carrier period;
- means for producing a fourth intermediate signal wherein said fourth intermediate signal is equal to said quantized second color difference signal multiplied by one half during the second and fourth sampling periods of each said carrier period, said quantized second color difference signal multiplied by minus one half during the sixth and eighth sampling periods of each said carrier period, and zero during the first, third, fifth, and seventh sampling periods of each said carrier period;
- means for producing a fifth intermediate signal wherein said fifth intermediate signal is equal to the sum of said quantized luminance signal, said first intermediate signal and said third intermediate signal;
- means for producing a sixth intermediate signal wherein said sixth intermediate signal is equal to the sum of said quantized luminance signal, said second intermediate signal and said fourth intermediate signal;
- and
- means for producing a digitized color signal wherein said digitized color signal is equal to said fifth intermediate signal during the first, third, fifth, and seventh sampling period of each said carrier period and said sixth intermediate signal during the second, fourth, sixth, and eighth sampling period of each said carrier period.
15 more elements
A digital color encoder, comprising:
- red, green, and blue primary color signals having a carrier frequency;
- a luminance signal wherein said luminance signal is equal to 0.299 multiplied by said red primary color signal plus 0.587 multiplied by said green primary color signal plus 0.114 multiplied by said blue primary color signal;
- means for producing a first color difference signal from said luminance signal and said red primary color signal wherein said first color difference signal is equal to said luminance signal divided by 1.14 subtracted from said red primary color signal divided by 1.14;
- means for producing a second color difference signal from said luminance signal and said blue primary color signal wherein said second color difference signal is equal to said luminance signal divided by 2.03 subtracted from said blue primary color signal divided by 2.03;
- a sampling frequency equal to eight times said carrier frequency;
- a sampling period equal to the inverse of said sampling frequency;
- a carrier period equal to the inverse of said carrier frequency wherein each said carrier period contains eight said sampling periods;
- a first control signal wherein said first control signal is equal to a logical during the first, third, fifth, and seventh sampling periods of each said carrier period and a logical 0 during the second, fourth, sixth, and eighth sampling periods of each said carrier period:
- a second control signal wherein said second control signal is equal to a logical 1 during the first, second, fifth, and sixth sampling periods of each said carrier period and a logical 0 during the third, fourth, seventh, and eighth sampling periods of each said carrier period;
- a third control signal wherein said third control signal is equal to a logical 1 during the first, second, third, and fourth sampling periods of each said carrier period and a logical 0 during the fifth, sixth, seventh, and eighth sampling periods of each said carrier period;
- means for sampling said luminance signal, said first color difference signal, and said second color difference signal at said sampling frequency thereby producing quantized levels of said luminance signal, said first color difference signal and said second color difference signal for each said sampling period;
- means for producing a first intermediate signal wherein said first intermediate signal is equal to said quantized first color difference signal during the first, second, fifth and sixth sampling periods of each said carrier period and said quantized second color difference signal during the third, fourth, seventh, and eighth sampling period of each said carrier period;
- means for producing a second intermediate signal wherein said second intermediate signal is equal to said quantized first color difference signal multiplied by one half added to said quantized second color difference signal multiplied by one half during the first, second, fifth, and sixth sampling periods of each said carrier period and said quantized first color difference signal multiplied by one half subtracted from said quantized second color signal multiplied by one half during the third, fourth, seventh, and eighth sampling periods of each said carrier period;
- means for producing a third intermediate signal wherein said third intermediate signal is equal to said first intermediate signal added to said quantized luminance signal during the first, second, third, and fourth sampling periods of each said carrier period and said first intermediate signal subtracted from said quantized luminance signal during fifth, sixth, seventh and eighth sampling periods of each said carrier period;
- means for producing a fourth intermediate signal wherein said fourth intermediate signal is equal to said second intermediate signal added to said quantized luminance signal during the first, second, third, and fourth sampling periods of each said carrier period and said second intermediate signal subtracted from said quantized luminance signal during the fifth, sixth, seventh and eighth sampling periods of each said carrier period;
- and
- means for producing a digitized color signal wherein said digitized color signal is equal to said third intermediate signal during the first, third, fifth, and seventh sampling periods of each said carrier period and said fourth intermediate signal during the second, fourth, sixth, and eighth sampling periods of each said carrier period.
14 more elements
Dependencies are inferred from the claim text.