1. Field of the Invention
The present invention generally relates to an imaging apparatus, and particularly to an imaging apparatus having a picture memory function to simultaneously achieve a recursive noise reduction circuit (hereinafter, referred to simply as xe2x80x9crecursive NR circuitxe2x80x9d), and long time accumulation (accumulation sensitivity increase) of CCD.
2. Description of the Related Art
Conventionally, such a recursive NR circuit has been used in a video system in order to reduce noise using a memory. However, semiconductor memories have recently developed to have large capacity at low cost, so that a memory and a recursive NR circuit have been incorporated in an imaging apparatus. Thus, the imaging apparatus have had the combination with various functions using memories.
For example, JP-A-5-23612 describes various functions using a recursive NR circuit and a memory system. Particularly, in the second noise reduction mode, the noise reduction effect is achieved by the recursive NR circuit and the accumulation sensitivity increase over 2-field periods.
Such a conventional imaging apparatus will be described with reference to FIG. 38. FIG. 38 is a schematic block diagram of a conventional imaging apparatus.
The imaging apparatus shown in FIG. 38 includes: a CCD 101 for converting a light image into an electrical image signal; a CDS 102 for sampling the electrical image signal; an A/D circuit 103 for converting the sampled image signal into a digital signal; a recursive NR circuit 104 that performs the recursive filtering process to the digital image signal in the time-axis direction to reduce the noise component of the image signal; a digital process circuit 105 that performs the necessary signal process to the recursive-filtered image signal; a D/A circuit 106 that converts the processed image signal into an analog signal to be output; a field memory 107 for storing an output signal of the recursive NR circuit 104; a field memory control circuit 108 for controlling the field memory 107; and a microcomputer 109 for controlling the whole imaging apparatus.
The field memory control circuit 108 delays the output signal of the recursive NR circuit 104 by one vertical scanning period, and outputs this delayed signal to the recursive NR circuit 104 as a cyclic signal.
The microcomputer 109 controls the cyclic coefficient of the recursive NR circuit 104, and controls the field memory control circuit 108 to write to and read from the field memory 107.
The CCD 101 is controlled by a charge reading pulse from a timing control circuit 110. The accumulation sensitivity increase is achieved when the microcomputer 109 controls the accumulation time that is input to the timing control circuit 110.
FIG. 39 is a timing chart showing the operation timing of this imaging apparatus in the normal operation.
As illustrated in FIG. 39, in the normal operation, the timing control circuit 110 outputs the charge reading pulse to the CCD 101 every vertical scanning period, so that the image signal is output from the CCD 101.
When an image signal x is output from the CCD 101, the cyclic coefficient K which is input from the microcomputer 109 to the recursive NR circuit 104 is set to be k. The recursive NR circuit 104 performs the arithmetic operation using the image signal x and an output signal Xxe2x88x922 of the field memory 107 to output the result as an output signal X. The output signal X is written to the field memory 107.
When an image signal x+1 is output from the CCD 101, the cyclic coefficient K which is input from the microcomputer 109 to the recursive NR circuit 104 is set to be xe2x80x9c0xe2x80x9d. Consequently, the output signal X of the field memory 107 is output from the recursive NR circuit 104 as the output signal X as it is. At this time, the output signal X of the recursive NR circuit 104 is not written to the field memory 107.
FIG. 40 is a timing chart showing the operation timing of this imaging apparatus in a 2-times accumulation sensitivity increase operation.
As illustrated in FIG. 40, when the accumulation sensitivity is increased twice, the timing control circuit 110 outputs the charge reading pulse to the CCD 101 every two vertical scanning periods. Therefore, the CCD 101 accumulates charges for two vertical scanning periods, and outputs the accumulated charges as an image signal.
When an image signal x is output from the CCD 101, the cyclic coefficient K which is input from the microcomputer 109 to the recursive NR circuit 104 is set to be k. The recursive NR circuit 104 performs the arithmetic operation using the image signal x and an output signal Xxe2x88x922 of the field memory 107 to output the result as an output signal X. The output signal X is written to the field memory 107.
When an image signal x+1 is output from the CCD 101, the timing control circuit 110 outputs no charge reading pulse, and hence the CCD 101 outputs no image signal.
Therefore, the cyclic coefficient K which is input from the microcomputer 109 to the recursive NR circuit 104 is set to be xe2x80x9c0xe2x80x9d so that the output signal X of the field memory 107 is output from the recursive NR circuit 104 as the output signal X as it is. In addition, the output signal X of the recursive NR circuit 104 is not written to the field memory 107.
Thus, the accumulation sensitivity can be increased twice, and at the same time the recursive NR can be achieved. Both of the sensitivity increase and the noise reduction can be attained.
In the above conventional imaging apparatus, however, the recursive NR is performed using the field memory 107, and the noise reduction operation by the recursive NR in the normal operation is performed by circulation of only one-field signal of the interlaced signal with the other-field signal not used. As a result, the vertical resolution is deteriorated. In addition, when the normal operation is changed to the accumulation sensitivity increase operation or when the accumulation sensitivity increase operation is changed to the normal operation, uncomfortable feeling occurs in the recursive NR operation.
It is an object of the invention to provide an imaging apparatus that has functions to use the both-fields signals of the interlaced signal for the recursive noise reduction in the normal operation, and to prevent the uncomfortable feeling in the recursive NR when the accumulation time of CCD (the accumulation sensitivity increase operation) is changed.
In order to achieve the above object, an imaging apparatus according to the first aspect of the invention includes:
imaging means for accumulating an image signal by an n-times long time accumulation (n is an integer of xe2x80x9c1xe2x80x9d or more);
timing control means for controlling to read out the image signal stored in the imaging means according to the n-times long time accumulation;
memory means for storing the image signal read out by the timing control means for one frame period or more;
memory control means for controlling the memory means; and
recursive noise reduction means for performing a noise reduction process on the basis of the image signal read out from the imaging means and the one-frame-period-or-more delayed image signal read out from the memory means to generate a noise-reduction processed image signal, wherein
when the imaging means performs a 2n-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes to the memory means the image signal generated by the recursive noise reduction means, and the recursive noise reduction means outputs the generated image signal as an output signal as it is; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated by the recursive noise reduction means to the memory means, and the recursive noise reduction means outputs the image signal read out from the memory means, as the output signal as it is.
This imaging apparatus may use the memory means such as a frame memory, and performs the recursive noise reduction process to the both-fields signal of the interlaced signal in the normal operation. Thereby, it is possible to reduce noise without deteriorating the vertical resolution. Further, even if the imaging means such as a CCD performs the 2n-times long time accumulation (or the accumulation sensitivity increase), it is possible to make the recursive noise reduction means operate properly.
In an imaging apparatus according to the second aspect of the invention, when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change the one-time accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the third aspect of the invention, when the long time accumulation in the imaging means changes from 2m-times (m is an integer of xe2x80x9c1xe2x80x9d or more, mxe2x89xa0n) to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2m-times to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2m-times accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the fourth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the fifth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in two or more vertical scanning periods after one vertical scanning period from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in two or more vertical scanning periods after one vertical scanning period from this change, the recursive noise reduction means outputs the image signal from the imaging means as the output signal as it is, without performing the noise reduction process. Thereby, it is possible to prevent the recursive noise reduction means from the uncomfortable feeling in operation. Further, it is possible to remove the uncomfortable feeling between the fields of the interlaced signal in the two vertical scanning periods.
In an imaging apparatus according to the sixth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means. Thereby, by outputting the opposite-field signal as the cyclic data after one vertical scanning period from the change, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the seventh aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means.
In this imaging apparatus, even when even when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means. Thereby, by outputting the opposite-field signal as the cyclic data after one vertical scanning period from the change to correct the xc2xd line vertical phase shift, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
An imaging apparatus according to the eighth aspect of the invention further comprises two of the memory means, wherein when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means.
In this imaging apparatus, when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to provide the imaging apparatus without any uncomfortable feeling.
In an imaging apparatus according to the ninth aspect of the invention, when the imaging means performs a (2n+1)-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated from the recursive noise reduction means to the memory means, and the recursive noise reduction means outputs the generated image signal as the output signal as it is; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated from the recursive noise reduction means to the memory means, and the recursive noise reduction means outputs the image signal read out from the memory means, as the output signal as it is, without performing the noise reduction process.
In this imaging apparatus, even when the imaging means performs the (2n+1)-times long time accumulation, it is possible to prevent the vertical resolution of the output signal from being deteriorated. Further, it is possible to provide the imaging apparatus in which the recursive noise reduction process can be performed using the interlaced signals with the same vertical phase.
An imaging apparatus according to the tenth aspect of the invention includes:
imaging means for accumulating an image signal by an n-times long time accumulation (n is an integer of xe2x80x9c1xe2x80x9d or more);
timing control means for controlling to read out the image signal stored in the imaging means according to the n-times long time accumulation;
memory means for storing the image signal read out by the timing control means for one frame period or more;
memory control means for controlling the memory means; and
recursive noise reduction means for performing a noise reduction process on the basis of the image signal read out from the imaging means and the one-frame-period-or-more delayed image signal read out from the memory means to generate a noise-reduced image signal, and for outputting the generated image signal to the memory control means, wherein
when the imaging means performs a 2n-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means reads out the one-frame-period-or-more delayed image signal stored in the memory means, outputs the read-out image signal, and writes the image signal generated by the recursive noise reduction means to the memory means; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated by the recursive noise reduction means to the memory means, reads out the one-frame-period-or-more delayed image signal stored in the memory means, and outputs the read-out image signal as an output signal as it is.
In this imaging apparatus, by using the memory means such as a frame memory, the recursive noise reduction process (the noise reduction process) is performed to the both-fields signals of the interlaced signal in the normal operation. Thereby, it is possible to reduce the noise component of the image signal without deteriorating the vertical resolution. Further, even when the imaging means such as a CCD performs the 2n-times long time accumulation (accumulation sensitivity increase) operation, it is possible to make the recursive noise reduction means operate properly, and to control the cyclic coefficient simply.
In an imaging apparatus according to the eleventh aspect of the invention, when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the one-time accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twelfth aspect of the invention, when the long time accumulation in the imaging means changes from 2m-times (m is an integer of xe2x80x9c1xe2x80x9d or more, mxe2x89xa0n) to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2m-times to 2n-times, after 2n vertical scanning periods from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2m-times accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the thirteenth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the fourteenth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in two vertical scanning periods or more after one vertical scanning period from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in two vertical scanning periods or more after one vertical scanning period from this change, the recursive noise reduction means reads out the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from having any uncomfortable feeling in the operation. Further, it is possible to remove the uncomfortable feeling between the fields of the interlaced signal in the two vertical scanning periods.
In an imaging apparatus according to the fifteenth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored to the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored to the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means. Thereby, by outputting the opposite-filed signal as the cyclic data after one vertical scanning period, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the sixteenth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means. Thereby, by producing the opposite-field signal as the cyclic data after one vertical scanning period from this change to correct for the xc2xd line vertical phase shift, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
An imaging apparatus according to the seventeenth aspect of the invention further comprises two of the memory means, wherein when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means.
In this imaging apparatus, when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to provide the imaging apparatus in which the uncomfortable feeling removed.
In an imaging apparatus according to the eighteenth aspect of the invention, when the imaging means performs a (2n+1)-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means reads out the one-frame-or-more delayed image signal stored in the memory means, outputs the read-out image signal as an output signal as it is, and writes the image signal generated from the recursive noise reduction means to the memory means; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated from the recursive noise reduction means to the memory means, and the recursive noise reduction means outputs the image signal read out from the memory means, as the output signal as it is.
In this imaging apparatus, even when the imaging means performs the (2n+1) times long time accumulation operation, it is possible to prevent the vertical resolution of the output signal from being deteriorated, and to provide the imaging apparatus in which the recursive noise reduction process is performed using the interlaced signals with the same vertical phase.
An imaging apparatus according to the nineteenth aspect of the invention, includes:
imaging means for accumulating an image signal by an n-times long time accumulation (n is an integer of xe2x80x9c1xe2x80x9d or more);
timing control means for controlling to read out the image signal stored in the imaging means according to the n-times long time accumulation;
memory means for storing the image signal read out by the timing control means for one frame period or more, and having first and second outputs;
memory control means for controlling the memory means; and
recursive noise reduction means for performing a noise reduction process on the basis of the image signal read out from the imaging means and the one-frame-period-or-more delayed image signal read out from the first outputs of the memory means to generate a noise-reduced image signal, and outputs the noise-reduced image signal to the memory control means, wherein
when the imaging means performs a 2n-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes to the memory means the image signal generated by the recursive noise reduction means, reads out the one-frame-period-or-more delayed image signal from the second output of the memory means, and outputs the read-out image signal as an output signal as it is; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated by the recursive noise reduction means to the memory means, reads out the one-frame-period-or-more delayed image signal from the second output of the memory means, and outputs the read-out image signal as an output signal as it is.
In this imaging apparatus, by using the memory means such as a frame memory, in the normal operation, the recursive noise reduction process (the noise reduction process) is performed to the both-fields signals of the interlaced signal. Thereby, it is possible to reduce the noise component of the image signal without deteriorating the vertical resolution. Further, even when the imaging means such as a CCD performs the 2n-times long time accumulation (accumulation sensitivity increase) operation, it is possible to make the recursive noise reduction means operate properly, and to control the cyclic coefficient and the memory output simply.
In an imaging apparatus according to the twentieth aspect of the invention, when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from one-time to 2n-times, after 2n vertical scanning periods from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the one-time accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twenty-first aspect of the invention, when the long time accumulation in the imaging means changes from 2m-times (m is an integer of xe2x80x9c1xe2x80x9d or more, mxe2x89xa0n) to 2n-times, after 2n vertical scanning periods from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2m-times (m is an integer of xe2x80x9c1xe2x80x9d or more, mxe2x89xa0n) to 2n-times, after 2n vertical scanning periods from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2m-times accumulation sensitivity increase operation to the 2n-times accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twenty-second aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twenty-third aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in two vertical scanning periods or more after one vertical scanning period from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in two vertical scanning periods or more after one vertical scanning period from this change, the memory control means reads out from the second outputs the image signal stored in the memory means, and outputs the read-out image signal as the output signal as it is, without performing the noise reduction process by the recursive noise reduction means. Thereby, it is possible to prevent the recursive noise reduction means from having uncomfortable feeling in the operation. Further, it is possible to remove the uncomfortable feeling between the fields of the interlaced signal in the two vertical scanning periods.
In an imaging apparatus according to the twenty-fourth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored to the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in a vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored to the memory means, and makes the recursive noise reduction means perform the noise reduction process on the basis of the read-out image signal of the opposite field and the image signal from the imaging means. Thereby, by outputting the opposite-field signal as the cyclic data after one vertical scanning period after the change, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twenty-fifth aspect of the invention, when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means.
In this imaging apparatus, even when the long time accumulation in the imaging means changes from 2n-times to one-time, in one vertical scanning period after one vertical scanning period from this change, the memory control means reads out an image signal of an opposite field stored in the memory means, makes vertical-phase correction means perform a vertical-phase correction process to correct the read-out image signal of the opposite field for xc2xd line spatial phase shift, and makes the recursive noise reduction means perform the noise reduction process on the basis of the vertical-phase-correction processed image signal and the image signal from the imaging means. Thereby, by outputting the opposite-field signal as the cyclic data after one vertical scanning period from the change to correct the xc2xd line vertical phase shift, it is possible to prevent the recursive noise reduction means from the erroneous operation, and to change from the 2n-times accumulation sensitivity increase operation to the one-time accumulation sensitivity increase operation without any uncomfortable feeling.
In an imaging apparatus according to the twenty-sixth aspect of the invention further comprises two of the memory means, wherein
when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means.
In this imaging apparatus, when the imaging means performs the long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to each memory means. Thereby, it is possible to prevent the recursive noise reduction means from the erroneous operation. Further, it is possible to provide the imaging apparatus without any uncomfortable feeling.
In an imaging apparatus according to the twenty-seventh aspect of the invention, when the imaging means performs a (2n+1)-times long time accumulation, in a vertical scanning period in which the image signal is output from the imaging means, the memory control means writes the image signal generated by the recursive noise reduction means to the memory means, reads out the one-frame-or-more delayed image signal stored in the memory means from the second output, and outputs the read-out image signal as an output signal as it is; and
in a vertical scanning period in which the image signal is not output from the imaging means, the memory control means inhibits the writing of the image signal generated from the recursive noise reduction means to the memory means, reads out the one-frame-or-more delayed image signal stored in the memory means from the second output, and outputs the read-out image signal as the output signal as it is.
In this imaging apparatus, even when the imaging means performs the (2n+1)-times long time accumulation, it is possible to prevent the vertical resolution of the output signal from being deteriorated, and to perform the recursive noise reduction process using the interlaced signals with the same vertical phase.