Image acquisition device removing distortion in image signals

• US 6,618,081 B1
• Filed: 11/26/1997
• Issued: 09/09/2003
• Est. Priority Date: 11/28/1996
• Status: Expired due to Fees

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Mouri, Takahiro, Shoji, Masumi, Harada, Sinji, Adachi, Iwao
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US08/979,167
• Time in Patent Office: 2,113 Days
• Field of Search: 348/207, 348/222, 348/231, 348/239, 348/241, 348/252, 348/335, 348/340, 348/500, 348/147, 348/207.99, 348/222.1, 348/231.99, 348/231.3, 348/231.6, 382/293, 382/44
• US Class Current: 348/231.6
• CPC Class Codes: H04N 1/053 in main scanning direction, e.g. synchronisation of line start or picture elements in a line
• CPC Class Codes: H04N 1/113 using oscillating or rotating mirrors
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 2201/0404 Scanning transparent media, e.g. photographic film
• CPC Class Codes: H04N 2201/04787 by changing or controlling the addresses or values of pixels, e.g. in an array, in a memory, by interpolation
• CPC Class Codes: H04N 2201/04793 using stored control or compensation data, e.g. previously measured data
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 5/253 Picture signal generating by scanning motion picture films or slide opaques, e.g. for telecine scanning details therefor H04N3/36 ; standard conversion therefor H04N7/0112

Abstract

The image acquisition device of the present invention includes an image forming lens to form a condensed image, a CCD to convert a condensed image to electric signals, and flag table memory to store predetermined correction flags, which indicate whether or not to cull a pixel so as to correct distortion caused by the image forming lens. The image acquisition device further includes a distortion correction circuit to execute the culling of pixels included in image signals in accordance with a correction flag for each pixel. The image acquisition device removes the distortion component contained in the image signal in real time.

Claims

1. An image acquisition device for converting an optical image formed via an optical system to a plurality of pixels, said image acquisition device comprising:

a storage means for storing predetermined correction data, said correction data identifying which of said plurality of pixels are to be culled to correct for distortion of said optical system, and

a correction means for executing the culling of said plurality of pixels by determining, for each pixel of said plurality of pixels, whether or not said each pixel of said plurality of pixels is to be culled in accordance with said correction data, and for said each pixel of said plurality of pixels that is to be culled, not writing said each pixel of said plurality of pixels that is to be culled to a pixel data output memory.

2. An image acquisition device according to claim 1, further comprising:

an image sensor, comprising a plurality of photoelectric conversion elements, for converting a condensed image to electric signals, said condensed image represented by said plurality of pixels,

an analog-to-digital converter coupled to said image sensor for converting said electric signals representing said condensed image into digital signals, and

a digital processing circuit coupled to said analog-to-digital converter, said digital processing circuit operative for performing correction processing on said digital signals, and for outputting an image strobe signal representing the location of a given pixel of said plurality of pixels.

3. An image acquisition device according to claim 1, wherein said correction means includes a distortion circuit comprising:

an address generator coupled to said digital processing circuit and operative for generating a pixel address in response to said image strobe signal, and

a determination circuit coupled to said address generator, said determination circuit operative for determining whether said each pixel of said plurality of pixels is to be culled, and for controlling writing/not-writing of said each pixel to said pixel data output memory in accordance with said determination.

4. An image acquisition device according to claim 3, said distortion circuit further comprising a flag table memory for storing predetermined correction flags, each of said correction flags indicating whether a given pixel of said plurality of pixels is to be culled.

5. An image acquisition device according to claim 3, wherein said pixel data output memory comprises a FIFO memory coupled to said determination circuit, said FIFO memory operative for storing pixel data upon receipt of a write signal transmitting by said determination circuit.

6. An image acquisition device according to claim 4, wherein said each of said plurality of pixels has a corresponding correction flag.

7. An image acquisition device according to claim 4, wherein a given correction flag indicates whether more than one pixel of said plurality of pixels should be culled.

8. An image acquisition device according to claim 4, further comprising at least one optical lens having a distortion component which is symmetrical about a given axis thereof.

9. An image acquisition device according to claim 8, wherein said correction flags represent correction data corresponding to a first portion of said optical lens, said correction flags corresponding to said first portion being repetitively utilized to correct for distortion caused other portions of said optical lens.

10. An image acquisition device according to claim 9, wherein only said correction flags representing correction data corresponding to a first portion of said optical lens are stored in said flag table memory.

11. An image acquisition device according to claim 10, wherein said address generator comprises:

a first register for storing a value representing the number of pixels in a line image in a first scan direction,

a second register for storing the number of pixels in a line image of a second scan direction,

a first comparator operative for controlling a first counter, said first counter being incremented if the value stored therein is less than one-half the value stored in said first register, and being decremented if the value stored therein is greater than one-half the value stored in said first register, and

a second comparator operative for controlling a second counter, said second counter being incremented if the value stored therein is greater than one-half the value stored in said second register, and being decremented if the value stored therein is greater than one-half the value stored in said second register,

said value of said first counter and said value of said second counter being utilized to select a correction flag.

12. An image acquisition device comprising:

an optical system for projecting an image,

means for obtaining image data by reading the image projected by said optical system, said image data representing said projected image and including a plurality of pixels, and

correction means for culling portions of said image data which represents a distortion of said image by determining, for each pixel of said plurality of pixels, whether or not said each pixel of said plurality of pixels is to be culled, and for said each pixel of said plurality of pixels that is to be culled, not writing said each pixel of said plurality of pixels that is to be culled to an image data output memory, said distortion being generated by said optical system.

13. An image acquisition device according to claim 12, wherein said means for obtaining image data comprises:

an image sensor, comprising a plurality of photoelectric conversion elements, for converting a condensed image to electric signals, said condensed image represented by said plurality of pixels,

an analog-to-digital converter coupled to said image sensor for converting said electric signals representing said condensed image into digital signals, and

a digital processing circuit coupled to said analog-to-digital converter, said digital processing circuit operative for performing correction processing on said digital signals, and for outputting an image strobe signal representing the location of a given pixel of said plurality of pixels.

14. An image acquisition device according to claim 13, wherein said correction means includes a distortion circuit comprising:

an address generator coupled to said digital processing circuit and operative for generating a pixel address in response to said image strobe signal, and

a determination circuit coupled to said address generator, said determination circuit operative for determining whether said each pixel of said plurality of pixels is to be culled, and for controlling writing/not-writing of said each pixel to said image data output memory in accordance with said determination.

15. An image acquisition device according to claim 14, said distortion circuit further comprising a flag table memory for storing predetermined correction flags, each of said correction flags indicating whether a given pixel of said plurality of pixels is to be culled.

16. An image acquisition device according to claim 15, wherein said image data output memory comprises a FIFO memory coupled to said determination circuit, said FIFO memory operative for storing pixel data upon receipt of a write signal transmitting by said determination circuit.

17. An image acquisition device according to claim 16, wherein said each of said plurality of pixels has a corresponding correction flag.

18. An image acquisition device according to claim 16, wherein a given correction flag indicates whether more than one pixel of said plurality of pixels should be culled.

19. An image acquisition device according to claim 16, further comprising at least one optical lens having a distortion component which is symmetrical about a given axis thereof.

20. An image acquisition device according to claim 19, wherein said correction flags represent correction data corresponding to a first portion of said optical lens, said correction flags corresponding to said first portion being repetitively utilized to correct for distortion caused other portions of said optical lens.

21. An image acquisition device according to claim 20, wherein only said correction flags representing correction data corresponding to a first portion of said optical lens are stored in said flag table memory.

22. An image acquisition device according to claim 21, wherein said address generator comprises:

a first register for storing a value representing the number of pixels in a line image in a first scan direction,

a second register for storing the number of pixels in a line image of a second scan direction,

a first comparator operative for controlling a first counter, said first counter being incremented if the value stored therein is less than one-half the value stored in said first register, and being decremented if the value stored therein is greater than one-half the value stored in said first register, and

a second comparator operative for controlling a second counter, said second counter being incremented if the value stored therein is greater than one-half the value stored in said second register, and being decremented if the value stored therein is greater than one-half the value stored in said second register,

said value of said first counter and said value of said second counter being utilized to select a correction flag.

23. An image acquisition device comprising:

a projection lens for projecting an image;

photoelectric conversion elements for reading the image projected by said projection lens and providing image data, the image data including a plurality of pixels,

means for moving said projected image relative to said photoelectric conversion elements a constant speed in a subscan direction,

memory for storing predetermined correction data corresponding to distortion caused by said projection lens; and

correction means for culling said image data in accordance with said predetermined correction data by determining, for each pixel of said plurality of pixels, whether or not said each pixel of said plurality of pixels is to be culled, and for said each pixel of said plurality of pixels that is to be culled, not writing said each pixel of said plurality of pixels that is to be culled to an image data output memory.

24. An image acquisition device according to claim 23, wherein said memory for storing predetermined correction data comprises a flag table memory for storing predetermined correction flags, each of said correction flags indicating whether a given pixel of said plurality of pixels representing said image is to be culled.

25. An image acquisition device according to claim 24, wherein said each of said plurality of pixels has a corresponding correction flag.

26. An image acquisition device according to claim 24, wherein a given correction flag indicates whether more than one pixel of said plurality of pixels should be culled.

27. An image acquisition device according to claim 26, further said projection lens has a distortion component which is symmetrical about a given axis thereof.

28. An image acquisition device comprising:

an image forming lens for forming a condensed image,

an image sensor, comprising a plurality of photoelectric conversion elements, for converting a condensed image to electric signals, said condensed image represented by a plurality of pixels,

a flag table memory for storing predetermined correction flags, each of said correction flags indicating whether a given pixel should be culled to correct for distortion caused by said image forming lens, and

a distortion correction circuit for culling said plurality of pixels by determining, for each pixel of said plurality of pixels, whether or not said each pixel of said plurality of pixels is to be culled, and for said each pixel of said plurality of pixels that is to be culled, not writing said each pixel of said plurality of pixels that is to be culled to a pixel image output memory.

29. An image acquisition device comprising:

a projection lens for projecting an image;

conversion means for reading the image and converting the read image to a plurality of pixels;

a pixel output memory receiving respective pixels to be output from the image acquisition device;

a memory for storing predetermined correction data identifying which of said plurality of pixels are to be culled to correct for distortion caused by said projection lens; and

a correction controller culling the plurality of pixels by determining, for each pixel of said plurality of pixels, whether or not said each pixel of said plurality of pixels is to be culled in accordance with said correction data, and for said each pixel of said plurality of pixels that is to be culled, not writing said each pixel of said plurality of pixels that is to be culled to a pixel data output memory.