Color image reading apparatus having variable exposure control

• US 4,891,692 A
• Filed: 11/06/1987
• Issued: 01/02/1990
• Est. Priority Date: 11/13/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Outa, Kenichi
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Powell, Mark R.
• Application Number:
  US07/117,752
• Time in Patent Office: 788 Days
• Field of Search: 358/75, 358/78, 358/80
• US Class Current: 358/506
• CPC Class Codes: H04N 1/40056 Circuits for driving or energising particular reading heads or original illumination means H04N1/401, H04N1/407 take precedence
• CPC Class Codes: H04N 1/4074 using histograms

Abstract

A color image reading apparatus for reading an image of a color negative film having: an exposing unit to expose the color film; a reading unit to read an image recorded on the color film by photoelectrically converting the transmission light from the exposed color film; a detector to detect a density of the image on the basis of an output from the reading unit; and a controller to control an exposure light quantity of the exposing means in accordance with the image density detected by the detector. The detector detects the image density on the basis of a histogram of the output from the reading unit or on the basis of an output of a special color which is output from the reading unit. With this apparatus, the reading operation suitable for the base density and image density of the color negative film can be performed.

Claims

1. An image reading apparatus comprising:

exposing means for exposing an original image;

reading means for reading an image by photoelectrically converting a light from the exposed original image;

detecting means for detecting a density of said image on the basis of a histogram of an output from said reading means; and

control means for controlling an exposure light quantity of said exposing means in accordance with the image density detected by said detecting means.

2. An apparatus according to claim 1, wherein the original image includes a color film image, and said reading means reads the image recorded on a a color film by photoelectrically converting a transmission light from the exposed color film.

3. An apparatus according to claim 1, wherein said detecting means detects the image density on the basis of an output of a special color which is output from said reading means.

4. An apparatus according to claim 1, wherein said control means controls the exposure light quantity of said exposing means in accordance with the image density detected by said detecting means, and in addition a base density of the original image.

5. An apparatus according to claim 1, wherein said detecting means detects the image density on the basis of the output of said reading means in accordance with a special condition.

10. An apparatus according to claim 1, wherein said reading means reads the original image line by line.

11. An apparatus according to claim 10, wherein said detecting means detects the image density on the basis of the output from said reading means, said output corresponding to a predetermined portion of the original image.

12. An apparatus according to claim 11, wherein said detecting means detects the image density on the basis of the output from said reading means which output corresponds to a predetermined number of lines of the original image.

13. An apparatus according to claim 1, wherein said detecting means detects the image density by obtaining a reference white level from the histogram of the output from said reading means.

14. An apparatus according to claim 1, wherein said detecting means detects the image density when a predetermined relationship is established among a plurality of signals which together constitute a color image signal from said reading means.

6. A color image reading apparatus comprising:

process means including exposing means for exposing a color film, and reading means for reading an image recorded on the color film by photoelectrically converting a transmission light from the exposed color film;

detecting means for detecting a base density of the color film and a density of said image; and

control means for controlling said process means in accordance with the base density and the image density which were detected by said detecting means.

7. An apparatus according to claim 6, wherein said detecting means detects the base density and the image density on the basis of an output of said reading means.

8. An apparatus according to claim 6, wherein said control means controls an exposure light quantity of said exposing means.

9. An apparatus according to claim 6, wherein said detecting means detects the image density on the basis of a histogram of an output of said reading means.

15. An apparatus according to claim 9, wherein said detecting means detects the image density by obtaining a reference white level from the histogram of an output of said reading means.

16. An apparatus according to claim 6, wherein said reading means reads the image recorded on the color film line by line.

17. An apparatus according to claim 16, wherein said detecting means detects the density of the image on the basis of an output of said reading means which output corresponds to a predetermined portion of the image recorded on the color film.

18. An apparatus according to claim 17, wherein said detecting means detects the image density on the basis of the output of said reading means which output corresponds to a predetermined number of lines of the image recorded on the color film.

19. An apparatus according to claim 7, wherein said detecting means detects the image density on the basis of the output of said reading means in accordance with a predetermined condition.

20. An apparatus according to claim 7, wherein said detecting means detects the image density on the basis of an output of a special color which is output from said reading means.

21. An apparatus according to claim 7, wherein said detecting means detects the image density when a predetermined relationship is established among a plurality of signals which together constitute a color image signal from said reading means.

22. An image reading apparatus comprising:

exposure means for exposing an image;

read means for reading the image by photoelectrically converting the exposed image line by line;

output means for outputting an output of said read means into an image output apparatus;

detection means for detecting a density of the image on the basis of the output of said read means, said output corresponding to a predetermined portion in the image; and

control means for controlling an exposure light quantity of said exposure means in accordance with the image density detected by said detection means and a base density of the image.

23. An apparatus according to claim 22, wherein said detection means detects the image density on the basis of a histogram of the output of said read means which output corresponds to a predetermined number of lines of the image.

24. An apparatus according to claim 22, wherein said detection means detects the image density on the basis of an output of a special color which is output from said read means.

25. An apparatus according to claim 22, wherein said image output apparatus includes a laser printer.

26. An apparatus according to claim 22, wherein said detection means detects the image density on the basis of the output of said read means in accordance with a predetermined condition.

27. An apparatus according to claim 22, wherein said detection means detects the image density by obtaining a reference white level from the histogram of the output of said read means.

28. An apparatus according to claim 22, wherein said detection means detects the image density when a predetermined relationship is established among a plurality of signals which together constitute a color image signal from said read means.

29. An apparatus according to claim 22, wherein the image includes a color film image, and said read means reads the image recorded on a color film by photoelectrically converting a transmission light from the exposed image.

30. An apparatus according to claim 22, wherein said detection means detects the image density on the basis of the output of said read means which output corresponds to a predetermined number of lines on the image.

31. An image reading apparatus comprising:

exposure means for exposing an image;

read means for reading the image by photoelectrically converting the exposed image line by line;

output means for outputting an output of said read means into an image output apparatus;

detection means for detecting a density of the image on the basis of the output of said read means, said output corresponding to a predetermined number of lines on the image; and

control means for controlling an exposure light quantity of said exposure means in accordance with the image density detected by said detection means.

32. An apparatus according to claim 31, wherein said detection means detects the image density on the basis of a histogram of the output of said read means which output corresponds to a predetermined number of lines of the image.

33. An apparatus according to claim 31, wherein said detection means detects the image density on the basis of an output of a special color which is output from said read means.

34. An apparatus according to claim 31, wherein said control means controls the exposure light quantity of said exposure means in accordance with the image density detected by said detection means, and in addition a base density of the image.

35. An apparatus according to claim 31, wherein said detection means detects the image density on the basis of the output of said read means in accordance with a predetermined condition.

36. An apparatus according to claim 31, wherein said detection means detects the image density by obtaining a reference white level from the histogram of the output of said read means.

37. An apparatus according to claim 31, wherein said detection means detects the image density when a predetermined relationship is established among a plurality of signals which together constitute a color image signal from said read means.

38. An apparatus according to claim 31, wherein the image includes a color film image, and said read means reads the image recorded on a color film by photoelectrically converting a transmission light from the exposed image.

39. An apparatus according to claim 31, wherein said image output apparatus includes a laser printer.