Digital colour cameras

Claim 2

A digital colour camera comprising: means (2R, 2B, 2G) for generating first, second and third digital colour signals, each with a sample rate of 4f sc (where f sc represents a colour sub-carrier frequency) from outputs of first, second and third imagers; means (5) for forming a digital luminance signal from said first, second and third digital colour signals; means (12, 13) for forming a dot-sequential colour difference signal in which first and second digital colour difference signals appear alternately at every 1/4f sc from said first, second and third digital colour signals; and means for passing said dot-sequential digital colour difference signal through digital filter means (14) so as to limit the band widths of said first and second digital colour difference signals.

Claim 3

A camera according to claim 1 wherein the frequency of a clock signal supplied to said means (12) for forming a dot-sequential colour difference signal is 2f sc .

Claim 4

A camera according to claim 2 wherein in the signal paths of said first and second digital colour signals and upstream of said means (12) for forming a dot-sequential colour difference signal are provided respective pre-filter means (11R, 11B) for eliminating aliasing noise.

Claim 5

A camera according to claim 1 wherein said first, second and third imagers are respective solid state colour imagers and produce respectively digital colour signals, each with a signal clock rate of 4f .

Claim 6

A camera according to claim 4 wherein said first, second and third solid state colour imagers (100R, 100B and 100G) have sensing elements of discrete type and said sensing elements are arranged in a spatially off-setting relation to one another (Figure 6A).

Claim 7

A camera according to claim 5 wherein said first, second and third solid state colour imagers (100R, 100B, 100G) are respective charge coupled devices.

Claim 8

A camera according to claim 6 wherein each said charge coupled devices (100R, 100B, 100G) is driven by a clock drive pulse of frequency 2f sc so as to produce an output, which is converted to a digital colour signal with a clock rate of 4f sc by a digital interpolator (101R, 101B, 101G).

Claim 9

A digital colour camera comprising: means (2R, 2B, 2G) for generating first, second and third digital colour signals, each with a sample rate of 4f sc (where f sc represents a colour sub-carrier frequency) from outputs of imagers; means (200) for forming a digital luminance signal from said first, second and third digital colour signals; means (200) for forming first and second digital colour difference signals from said first, second and third digital colour signals; pre-filter means (201I, 201Q) for limiting the band widths of said first and second digital colour difference signals; means (202) for generating a dot-sequential digital colour difference signal where said first and second digital colour difference signals appear at every 1/4f sc from said first and second digital colour difference signals whose band widths have been limited; and means for passing said dot-sequential digital colour difference signal through digital filter means (203, 208) so as to limit the band widths of said first and second digital colour difference signals.

Claim 10

A digital colour camera comprising: means (2R, 2B, 2G) for generating first, second and third digital colour signals, each with a sample rate of 4f sc (where f sc represents a colour sub-carrier frequency) from outputs of imagers; means (200) for forming a digital luminance signal from said first, second and third digital colour signals; means (200) for forming first and second digital colour difference signals from said first, second and third digital colour signals; pre-filter means (201I, 201Q) for limiting the band widths of said first and second digital colour difference signals; means (202) for generating a dot-sequential digital colour difference signal where said first and second digital colour difference signals appear at every 1/4f sc from said first and second digital colour difference signals whose band widths have been limited; and means for passing said dot-sequential digital colour difference signal through digital filter means (203, 208) so as to limit the band widths of said first and second digital colour difference signals.

Claim 11

A digital colour camera comprising: means (2R, 2B, 2G) for generating first, second and third digital colour signals, each with a sample rate of 4f sc (where f sc represents a colour sub-carrier frequency) from outputs of imagers; means (200) for forming a digital luminance signal and first and second digital colour difference signals from said first, second and third digital colour signals; means (202) for generating a dot-sequential digital colour difference signal in which said first and second digital colour difference signals appear alternately every ¼f sc ; first digital filter means (203) supplied with said dot-sequential digital colour difference signal so as to limit the band width of said first digital colour difference signal; and second digital filter means (208) having a narrower pass band compared with said first digital filter (203) and supplied with said dot-sequential digital colour difference signal whose band is limited already so as to limit the band width of said second colour difference signal.

Claim 12

A digital colour camera comprising: means (2R, 2B, 2G) for generating first, second and third digital colour signals, each with a sample rate of 4f sc (where f sc represents a colour sub-carrier frequency) from outputs of imagers; means (200) for forming a digital luminance signal and first and second digital colour difference signals from said first, second and third digital colour signals; means (202) for generating a dot-sequential digital colour difference signal in which said first and second digital colour difference signals appear alternately every ¼f sc ; first digital filter means (203) supplied with said dot-sequential digital colour difference signal so as to limit the band width of said first digital colour difference signal; and second digital filter means (208) having a narrower pass band compared with said first digital filter (203) and supplied with said dot-sequential digital colour difference signal whose band is limited already so as to limit the band width of said second colour difference signal.