Image processing method and apparatus

• US 6,459,436 B1
• Filed: 11/10/1999
• Issued: 10/01/2002
• Est. Priority Date: 11/11/1998
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ohga, Manabu, Kumada, Shuichi
• Primary Examiner(s): Luu, Matthew
• Assistant Examiner(s): Sajous, Wesner
• Application Number:
  US09/437,322
• Time in Patent Office: 1,056 Days
• Field of Search: 358/500, 358/522, 358/501, 358/504, 358/515, 358/516-518, 358/519-521, 348/223, 348/657, 348/658, 348/649-650, 348/655, 348/656, 348/675, 348/607, 348/624, 348/659, 348/674, 348/645, 348/600, 348/602, 348/722, 348/582, 348/603, 382/162-167, 382/171-173, 345/589-591, 345/593, 345/597, 345/600, 345/604-606, 345/617-620
• US Class Current: 345/590
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature
• CPC Class Codes: H04N 1/6088 by viewing conditions, i.e. conditions at picture output

Abstract

When gamut mapping (hue restoration) defined by one Lab color space is applied in color matching under different reference white points, human vision perceives the hue as inconsistent. In view of this, input data which is dependent on a color space of an input device is converted by a first conversion LUT to color space data which is independent of any devices, based on a viewing condition at the time of viewing an input original. The device independent data is converted to data in the human color perception space by a forward converter, subjected to gamut mapping, and converted back to device independent data in the color space independent of any devices by an inverse converter, based on a viewing condition at the time of viewing an output original. Then, the device independent data is converted to output data in a color space which is dependent on an output device by a second conversion LUT.

Claims

1. An image processing method of outputting an image, on which a color conversion process in accordance with input and output image viewing conditions is performed by using a color perception model, to a monitor, comprising the steps of:

performing forward conversion processing of the color perception model on input image data to convert the input image data into a color perception space;

performing inverse conversion processing of the color perception model on the input image data in the color perception space, wherein the inverse conversion processing includes partial adaptation processing in accordance with white of ambient light and white of the monitor which are included in the output image viewing condition; and

inputting a user instruction, by using a graphical user interface, to independently adjust the input image viewing condition, the output image viewing condition and a condition used in the partial adaptation processing.

2. The method according to claim 1, wherein the forward conversion processing performs incomplete adaptation processing in accordance with the input image viewing condition, and the inverse conversion processing performs incomplete adaptation processing in accordance with the output image viewing condition.

3. The method according to claim 1, wherein a ratio of the white of the ambient light to the white of the monitor is set to three to seven as a coefficient of the partial adaptation processing, in advance.

4. The method according to claim 1, wherein the color conversion process is performed with a color matching process between an image inputting device and an image outputting device.

5. The method according to claim 4, further comprising the steps of:

converting the input image data in accordance with a profile according to the image inputting device;

performing the color conversion process on the converted image data; and

converting the image data, on which the color conversion process is performed, in accordance with a profile according to the image outputting device.

6. The method according to claim 1, further comprising the step of disabling, if a device except the monitor is selected as an image outputting device, the adjustment of the condition used in the partial adaptation processing.

7. The method according to claim 1, further comprising the steps of:

converting the input image data depended on an image inputting device into a color space which is independent of devices; and

converting the converted image data into a color space depended on the monitor.

8. The method according to claim 7, further comprising the step of dynamically generating a converting condition used in said converting steps by using the color perception model.

9. A computer readable medium comprising computer program codes, for a method of outputting an image, on which a color conversion process in accordance with input and output image viewing conditions is performed by using a color perception model, to a monitor, comprising process procedure code for:

performing forward conversion processing of the color perception model on input image data to convert the input image data into a color perception space;

performing inverse conversion processing of the color perception model on the input image data in the color perception space, wherein the inverse conversion processing includes partial adaptation processing in accordance with white of ambient light and white of the monitor which are included in the output image viewing condition; and

inputting a user instruction, by using a graphical user interface, to independently adjust the input image viewing condition, the output image viewing condition and a condition used in the partial adaptation processing.

10. A computer program product comprising computer program codes, for a method of outputting an image, on which a color conversion process in accordance with input and output image viewing conditions is performed by using a color perception model, to a monitor, comprising process procedure code for:

performing forward conversion processing of the color perception model on input image data to convert the input image data into a color perception space;

performing inverse conversion processing of the color perception model on the input image data in the color perception space, wherein the inverse conversion processing includes partial adaptation processing in accordance with white of ambient light and white of the monitor which are included in the output image viewing condition; and

inputting a user instruction, by using a graphical user interface, to independently adjust the input image viewing condition, the output image viewing condition and a condition used in the partial adaptation processing.

11. An image processing apparatus for outputting an image, on which a color conversion process in accordance with input and output image viewing conditions is performed by using a color perception model, to a monitor, said apparatus comprising:

a first converter, arranged to perform forward conversion processing of the color perception model on input image data to convert the input image data into a color perception space;

a second converter, arranged to perform inverse conversion processing of the color perception model on the input image data in the color perception space, wherein the inverse conversion processing includes partial adaptation processing in accordance with white of ambient light and white of the monitor which are included in the output image viewing condition; and

a graphical user interface, arranged to input a user instruction to independently adjust the input image viewing condition, the output image viewing condition and a condition used in the partial adaptation processing.