1-chip color video camera for generating inter-pixel color signal component by interpolating primary color signals from neighboring pixels

• US 5,852,468 A
• Filed: 02/21/1996
• Issued: 12/22/1998
• Est. Priority Date: 02/27/1995
• Status: Expired due to Term

• Current Assignee: Xacti Corporation (Office Support KK)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Okada, Hidefumi
• Primary Examiner(s): Faile, Andrew I.
• Assistant Examiner(s): ONUAKU, CHRISTOPHER O
• Application Number:
  US08/604,482
• Time in Patent Office: 1,035 Days
• Field of Search: 348/272, 348/273, 348/280, 348/263, 348/625, 348/630, 348/717, 348/266, 348/268, 348/269, 348/277, 348/281, 348/282, 348/320, 348/321, 348/322, 348/323, 348/324, 348/624
• US Class Current: 348/272
• CPC Class Codes: H04N 2209/046 Colour interpolation to calculate the missing colour values
• CPC Class Codes: H04N 23/843 Demosaicing, e.g. interpolating colour pixel values
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 9/646 for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters

Abstract

A 1-chip color video camera which provides a frequency characteristic that exhibits relatively little attenuation up to a high frequency range for a (green) signal and has a highest degree of contribution to brightness, and hence provides high resolution. The 1-chip color video camera has a color separation circuit for processing signals obtained from a solid-state image sensor wherein primary color filters of R(red), G and B(blue) are arranged mosaic-wise for respective pixels. Color signal components at a central portion of a pixel block consisting of four pixels of two rows by two columns on the solid-state image sensor are generated by interpolating color signal components of a plurality of neighboring pixels.

Claims

1. A 1-chip color video camera, comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means including on its light receiving surface a color filter array in which primary color filters are placed in a prescribed arrangement corresponding to said photoelectric converting elements; and

interpolating means, receiving an output from said solid-state image sensing means, for outputting color signals;

said interpolating means including;

parallel color signal output means, receiving said output from said solid-state image sensing means, for outputting, as said color signals, color signals corresponding to a prescribed even number of rows of said pixels in synchronization with and parallel to each other successively, column by column;

control means for outputting a synchronized interpolation designating signal in accordance with correspondence between said color signals, output column by column from said parallel color signal output means, and an arrangement of predetermined weight coefficients for the prescribed arrangement of said color filter array; and

color separation means, receiving said outputs from said parallel color signal output means, for interpolating color signals from a pixel block including pixels of said prescribed even number of rows and a prescribed even number of columns in accordance with said interpolation designating signal, and for successively outputting color signals in synchronization with and corresponding to a central position of said pixel block.

6. The 1-chip color video camera according to claim 1, further comprising:

analog-to-digital converting means, receiving said output from said solid-state image sensing means, for outputting a corresponding digital signal thereto;

wherein

said parallel color signal output means includes (2k-1) line memories, where 2k represents said prescribed even number;

each of said line memories having transfer capacity corresponding to a row of said pixels, and said line memories being connected in series to receive as an initial stage input, an output from said analog-to-digital converting means; and

said parallel color signal output means outputs, in parallel, said output from said analog-to-digital converting means and outputs from said line memories; and

said color separation means includes;

a two-dimensional transfer register, receiving said parallel color signal outputs, for successively transferring said parallel color signal outputs to a prescribed direction, and holding at most 2k×

2k color signal values; and

interpolation calculation means, responsive to said interpolation designating signal, for adding corresponding ones of said color signals held in said two-dimensional transfer register to each other, in accordance with an arrangement of said weight coefficients.

7. The 1-chip color video camera according to claim 6, wherein:

said color filter array includes green filters arranged in a diagonal direction in an arbitrary color filter arrangement of two rows by two columns; and

said interpolation calculation means outputs, in accordance with said interpolation designating signal, a green signal corresponding to a central position of said pixel block as either a mean value of color signal values of (k, k) and (k+1, k+1) or a mean value of color signal values of (k+1, k) and (k, k+1), of the two-dimensional arrangement of said 2k×

2k color signal values.

8. The 1-chip color video camera according to claim 6, wherein:

said prescribed even number is 4;

said color filter array includes red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately;

said two-dimensional transfer register holds signals from a pixel block including sixteen pixels of four rows by four columns; and

said interpolation calculation means switches, in accordance with said interpolation designating signal, values of sums of weight coefficients in every column in a vertical direction for color signals corresponding to said sixteen pixels to 0, 3, 0, 1! or 1, 0, 3, 0!, for interpolating and outputting color signal component of each of red and blue at a central portion of said pixel block.

9. The 1-chip color video camera according to claim 6, wherein:

said prescribed even number is 4;

said color filter array includes red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately;

said two-dimensional transfer register holds signals from a pixel block including sixteen pixels of four rows by four columns; and

said interpolation calculation means for switching, in accordance with said interpolation designating signal, values of sums of weight coefficients of every row in horizontal direction for color signals corresponding to said sixteen pixels to 0, 3, 0, 1! or 1, 0, 3, 0!, and for interpolating and outputting a color signal component of each of red and blue at a central portion of said pixel block.

10. The 1-chip color video camera according to claim 6, wherein:

said prescribed even number is 4;

said color filter array includes red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately;

said two-dimensional transfer register holds signals from a pixel block including sixteen pixels of four rows by four columns; and

said interpolation calculation means performs interpolation in accordance with said interpolation designating signal, where said pixel block of 16 pixels includes sixteen pixels of four rows by four columns of (m, n) to (m+3, n30

     3), by;

setting a weight coefficient of a pixel (m+1, n+1) to 2 and a weight coefficient of each of pixels (m+1, n30

     3) and (m+3, n+1) to 1, when either a red or a blue color filter is placed on the pixel (m+1, n+1);

setting a weight coefficient of a pixel (m+1, n+2) to 2 and a weight coefficient of each of pixels (m+1, n) and (m+3, n+2) to 1, when either a red or a blue color filter is placed on the pixel (m+1, n+2);

setting a weight coefficient of a pixel (m+2, n+1) to 2 and a weight coefficient of each of pixels (m, n+1) and (n+2, n30

     3) to 1, when either a red or a blue color filter is placed on the pixel (m+2, n+1); and

setting a weight coefficient of a pixel (m+2, n+2) to 2 and a weight coefficient of each of pixels (m, n+2) and (m+2, n) to 1, when either a red or a blue color filter is placed on the pixel (m+2, n+2).

2. A 1-chip color video camera, comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means including on its light receiving surface a color filter array in which primary color filters are arranged mosaic-wise corresponding to said photoelectric converting elements;

said color filter array having green filters placed in a diagonal direction in an arbitrary color filter arrangement of two rows by two columns; and

interpolating means, receiving an output from said solid-state image sensing means, for interpolating a green signal component at a central portion of a pixel block corresponding to said arbitrary color filter arrangement of two rows by two columns, using a mean value of a plurality of green signals from those of said photoelectric converting elements which correspond to said green filters placed in the diagonal direction.

3. A 1-chip color video camera, comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means including, on its light receiving surface, a color filter array in which primary color filters are arranged mosaic-wise corresponding to said photoelectric converting elements; and

said color filter array having red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately; and

interpolating means for interpolating, based on signals from a pixel block including sixteen pixels of four rows by four columns, a color signal component of each of red and blue at a central portion of said pixel block;

said interpolating means including a two-dimensional non-recursive digital filter circuit for switching, in accordance with an arrangement of the color filters corresponding to said sixteen pixels, values of sums of weight coefficients of every column in a vertical direction to 0, 3, 0, 1! or 1, 0, 3, 0!.

4. A 1-chip color video camera comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means including, on its light receiving surface, a color filter array in which primary color filters are arranged mosaic-wise corresponding to said photoelectric converting elements; and

said color filter array having red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately; and

interpolating means for interpolating, based on signals from a pixel block including sixteen pixels of four rows by four columns, a color signal component of each of red and blue at a central portion of said pixel block;

said interpolating means including a two-dimensional non-recursive digital filter for switching, in accordance with an arrangement of the color filters corresponding to said sixteen pixels, values of sums of weight coefficients of every row in a horizontal direction to 0, 3, 0, 1! or 1, 0, 3, 0!.

5. A 1-chip color video camera, comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means including, on its light receiving surface, a color filter array in which primary color filters are arranged mosaic-wise corresponding to said photoelectric converting elements; and

said color filter array having red filters and blue filters arranged checkerwise, with rows including said red filters and rows including said blue filters being arranged alternately; and

interpolating means for interpolating, based on signals from a pixel block including sixteen pixels of four rows by four columns, a color signal component of each of red and blue at a central portion of said pixel block; and

said interpolating means including a two-dimensional non-recursive digital filter circuit;

wherein when said pixel block of sixteen pixels includes sixteen pixels of four rows by four columns from (m, n) to (m+3, n+3) with m and n being integers; and

said two-dimensional non-recursive digital filter circuit performs interpolation by;

setting a weight coefficient of a pixel (m+1, n+1) to 2 and a weight coefficient of each of pixels (m+1, n30

     3) and (m+3, n+1) to 1, when either a red or a blue color filter is placed on the pixel (m+1, n+1);

setting a weight coefficient of a pixel (m+1, n+2) to 2 and a weight coefficient of each of pixels (m+1, n) and (m+3, n+2) to 1, when either a red or a blue color filter is placed on the pixel (m+1, n+2);

setting a weight coefficient of a pixel (m+2, n+1) to 2 and a weight coefficient of each of pixels (m, n+1) and (m+2, n30

     3) to 1, when either a red or a blue color filter is placed on the pixel (m+2, n+1); and

setting a weight coefficient of a pixel (m+2, n+2) to 2 and a weight coefficient of each of pixels (m, n+2) and (m+2, n) to 1, when either a red or a blue color filter is placed on the pixel (m+2, n+2).

11. A 1-chip color video camera, comprising:

solid-state image sensing means provided with photoelectric converting elements corresponding to respective pixels arranged in an array;

said solid-state image sensing means, including on its light receiving surface a color filter array in which primary color filters are arranged mosaic-wise corresponding to said photoelectric converting elements; and

interpolating means for generating each of a plurality of primary color signal components at a position shifted by half a pixel in horizontal and vertical directions from a center of an arbitrary pixel, from color signal components of a plurality of neighboring pixels, based on a predetermined weighted average of corresponding primary color signal components from a plurality of neighboring pixels to the center pixel and according to a prescribed arrangement of said color filter array.

12. A 1-chip color video camera, comprising:

solid-state image sensing means having color filters of three primary colors of R, G and B (red, green and blue, respectively) arranged mosaic-wise corresponding to respective pixels;

color separation means for processing a signal from said solid-state image sensing means;

said color separation means including signal processing means for performing weighted average processing to obtain a weighted average of R, G and B color signal components at a central position of a pixel block consisting of 16 pixels of 4 rows by 4 columns of (m, n) to (m+3, n30

     3), where m and n are integers, using a prescribed weight coefficient for a signal from a prescribed pixel in said pixel block, wherein;

if a first value is larger than a second value, said weighted average processing is performed when;

i) the R or B color filter is arranged on a pixel at (m+1, n+1), and using a weight coefficient for the pixel (m+1, n+1) as the first value and a weight coefficient of pixels at (m+1, n30

     3) and (m+3, n+1) as the second value;

ii) the R or B color filter is arranged on a pixel at (m+1, n+2), and using a weight coefficient for the pixel (m+1, n+2) as the first value and a weight coefficient of pixels at (m+1, n) and (m+3, n+2) as the second value;

iii) the R or B color filter is arranged on a pixel at (m+2, n+1), and using a weight coefficient for the pixel (m+2, n+1) as the first value and a weight coefficient of pixels at (m, n+1) and (m+2, n30

     3) as the second value; and

iv) the R or B color filter is arranged on a pixel at (m+2, n+2), and using a weight coefficient for the pixel (m+2, n+2) as the first value and a weight coefficient of pixels at (m, n+2) and (m+2, n) as the second value.

13. A 1-chip video camera, comprising:

solid-state image sensing means having color filters of three primary colors R, G and B (red, green and blue, respectively) arranged mosaic-wise corresponding to respective pixels; and

interpolating means for generating R, G and B color signal data at a central position of a pixel block, the block consisting of an arbitrary v rows by v columns, where v is an even number, and using a prescribed weight coefficient for a signal for each color for a prescribed pixel in said pixel block.

14. A 1-chip color video camera according to claim 13, wherein said color filters comprises:

B color filters and G color filters arranged alternately for each of the pixels in one row of every two rows adjacent to each other in a vertical direction; and

G filters and R filters arranged alternately offset by one pixel in the vertical direction from said one row, and on each one of the pixels of the other one of said two rows.