Apparatus for providing variable gamma correction in both on-line and off-line modes of operation

• US 5,453,845 A
• Filed: 04/28/1994
• Issued: 09/26/1995
• Est. Priority Date: 10/27/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Saito, Seiji, Nonoshita, Hiroshi, Shigehara, Yasuhisa, Cho, Kenjiro
• Primary Examiner(s): Harvey, David E.
• Application Number:
  US08/235,132
• Time in Patent Office: 516 Days
• Field of Search: 348/661, 348/674, 348/680, 348/254, 358/403, 358/406, 358/408, 358/455, 358/458, 358/460, 358/518, 358/519, 358/521, 358/523, 358/443, 358/448, 358/442, 358/296
• US Class Current: 358/442
• CPC Class Codes: H04N 1/407 Control or modification of tonal gradation or of extreme levels, e.g. background level

Abstract

An image processing apparatus is disclosed which includes circuitry for selectively applying variable gamma corrections to an image signal during both on-line and off-line modes of operation. In the off-line mode, the apparatus operates to simultaneously correct image signals for non-linearities produced by both an input device and an output device. In the on-line mode, correction is made for the non-linearities of the input device and a separate correction is made for the non-linearities of the output device. Such operation allows the apparatus to process linear data in the on-line mode.

Claims

1. An image processing system which operates in an on-line mode and an off-line mode, comprising:

an input means for inputting image information;

an output means for outputting image information;

a first correction means having a first correction function for correcting the image information input by said input means in accordance with an input-output characteristic of said input means and said output means for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of said input means;

a memory means for storing the corrected image information provided by said first correction means;

a second correction means for further correcting the stored corrected image information in accordance with an input-output characteristic of said output means for providing on-line image information; and

a selection means for providing the off-line image information from said first correction means to said output means when said image processing system is operating in the off-line mode, and when said image processing system is operating in the on-line mode for providing the corrected image information from said first correction means to said memory means for storage, and the on-line image information from said second correction means to said output means.

2. An image processing system according to claim 1, further comprising means for editing the corrected image information stored in said memory means.

3. An image processing system according to claim 1, wherein said first and second correction means has respective correction tables and executes correction operations using their respective correction tables.

4. An image processing system connected to an input apparatus and to an output apparatus, which operates in either one of first and second modes, said system comprising:

first correction means having a first correction function for correcting image information input by the input apparatus in accordance with an input-output characteristic of the input apparatus and the output apparatus for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of the input apparatus;

memory means for storing the corrected image information provided by said first correction means;

second correction means for further correcting the stored corrected image information in accordance with an input-output characteristic of the output apparatus for providing on-line image information; and

selection means for providing the off-line image information from said first correction means to the output apparatus when said image processing system is operating in the second mode, and when said image processing system is operating in the first mode for providing the corrected image information from said first correction means to said memory means for storage, and the on-line image information from said second correction means to the output apparatus.

5. An image processing system according to claim 4, further comprising means for editing the corrected image information stored in said memory means.

6. An image processing system according to claim 4, wherein said first and second correction means have respective correction tables and execute correction operations using their respective correction tables.

7. A method of operating an image processing system in an on-line mode and an off-line mode, comprising the steps of:

inputting image information into said image processing system from an input device;

outputting image information from an output device;

correcting the image information input by said input device, using a first correction device having a first correction function, in accordance with an input-output characteristic of said input device and said output device for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of said input device;

storing the corrected image information provided by said first correction device in a memory device;

further correcting the stored corrected image information using a second correction device in accordance with an input-output characteristic of said output device for providing on-line image information; and

providing the off-line image information, using a selection device, from said first correction device to said output device when said image processing system is operating in the off-line mode, and when said image processing system is operating in the on-line mode for providing the corrected image information from said first correction device to said memory device for storage, and the on-line image information from said second correction device to said output device.

8. The method according to claim 7, including the step of:

editing the corrected image information stored in said memory device.

9. The method according to claim 7, wherein said first and second correction devices have respective correction tables and execute correction operations using their respective correction tables.

10. A method of operating an image processing system connected to an input apparatus and to an output apparatus, which operates in either one of first and second modes, said method comprising the steps of:

correcting image information, using a first correction device having a first correction function, input by the input apparatus in accordance with an input-output characteristic of the input apparatus and the output apparatus for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of the input apparatus;

storing the corrected image information provided by said first correction device in a memory device;

further correcting the stored corrected image information, using a second correction device, in accordance with an input-output characteristic of the output apparatus for providing on-line image information; and

providing the off-line image information, using a selection device, from said first correction device to the output apparatus when said image processing system is operating in the second mode, and when said image processing system is operating in the first mode for providing the corrected image information from said first correction device to said memory device for storage, and the on-line image information from said second correction device to the output apparatus.

11. The method according to claim 10, including the step of:

editing the corrected image information stored in said memory device.

12. The method according to claim 10, wherein said first and second correction devices have respective correction tables and execute correction operations using their respective correction tables.

13. An image processing system which operates in an on-line mode and an off-line mode, comprising:

an input means for inputting information including image information of multivalue digital data;

an output means for outputting image information;

a first correction means having a first correction function for correcting the image information input by said input means in accordance with an input-output characteristic of said input means being different from substantially 1, and said first correction means can directly correct the image information entered by said input means in response to input-output characteristics of said input means and said output means for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of said input means;

a memory means for storing the corrected image information provided by said first correction means;

a second correction means for further correcting the stored corrected image information in accordance with an input-output characteristic of said output means for providing on-line image information; and

a selection means for providing the off-line image information from said first correction means to said output means when said image processing system is operating in the off-line mode, and when said image processing system is operating in the on-line mode for providing the corrected image information from said first correction means to said memory means for storage, and the on-line image information from said second correction means to said output means.

14. A system according to claim 13, further comprising process means for editing the image information stored in said memory means.

15. A system according to claim 13, further comprising process means for processing the image information stored in said memory means.

16. A system according to claim 13, wherein said system is constituted by a plurality of apparatuses.

17. A method of operating an image processing system in an on-line mode and on off-line mode, comprising the steps of:

inputting information including image information of multivalue digital data into said image processing system from an input device;

outputting image information from an output device;

correcting the image information input by said input device, using a first correction device having a first correction function, in accordance with an input-output characteristic of said input device being different from substantially 1, and said first correction device can directly correct the image information entered by said input device in response to input-output characteristics of said input device and said output device for providing off-line image information, and a second correction function for providing corrected image information which is independent of the input-output characteristic of said input device;

storing the corrected image information provided by said first correction device in a memory device;

further correcting the stored corrected image information, using a second correction device, in accordance with an input-output characteristic of said output device for providing on-line image information; and

providing the off-line image information, using a selection device, from said first correction device to said output device when said image processing system is operating in the off-line mode, and when said image processing system is operating in the on-line mode for providing the corrected image information from said first correction device to said memory device for storage, and the on-line image information from said second correction device to said output device.

18. An image processing method according to claim 17, further comprising the step of converting the image information being transferred in said transferring step which is as if the input-output characteristic were substantially 1 to image information which is suitable for the output means taking an input-output characteristic of the output means into consideration.

19. A method according to claim 17, further comprising the step of editing the image information stored in said storing step.

20. A method according to claim 17, further comprising the step of processing the image information stored in said storing step.

21. A method according to claim 17, wherein said method is performed in a system comprising a plurality of apparatuses each of which performs said method.