Automatic tone mapping for images

• US 7,136,073 B2
• Filed: 10/17/2002
• Issued: 11/14/2006
• Est. Priority Date: 10/17/2002
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Newman, Todd
• Primary Examiner(s): Zimmerman, Mark
• Assistant Examiner(s): AMIN, JWALANT B
• Application Number:
  US10/271,579
• Publication Number:
  US 20040075744A1
• Time in Patent Office: 1,489 Days
• Field of Search: None
• US Class Current: 345/589
• CPC Class Codes: H04N 1/4072 dependent on the contents of the original
• CPC Class Codes: H04N 1/6072 adapting to different types of images, e.g. characters, graphs, black and white image portions

Abstract

An image processing method for processing image data comprises the steps of obtaining scanpath data corresponding to original image data, determining regions of interest for the original image data based on the obtained scanpath data, and mapping tone values of the original image data corresponding to each region of interest in order to obtain tone-mapped image data.

Claims

1. An image processing method for processing image data, the method comprising the steps of:

an obtaining step of obtaining scanpath data corresponding to original image data;

an ROI determining step of determining regions of interest for the original image data based on the obtained scanpath data;

a parameter determining step of determining tone mapping parameters for each region of interest from said ROI determining step; and

a mapping step of mapping tone values of the original image data corresponding to each region of interest from said ROI determining step based on corresnonding tone mapping parameters from said parameter determining step in order to obtain tone-mapped image data.

2. The image processing method of claim 1, wherein the scanpath data is obtained by application of a scanpath predictor algorithm to the original image data.

3. The image processing method of claim 2, wherein the scanpath algorithm detects edges in the original image data in order to obtain the scanpath data.

4. The image processing method of claim 3, wherein edges are detected by passing the image through an edge-detection filter.

5. The image processing method of claim 2, wherein the scanpath algorithm detects luminance shifts in the original image data to obtain the scanpath data.

6. The image processing method of claim 2, wherein the scanpath algorithm detects contrast shifts in the original image data to obtain the scanpath data.

7. The image processing method of claim 1, wherein the scanpath data is obtained by aggregation of scanpath data obtained from each of a plurality of scanpath predictor algorithms.

8. The method of claim 7, wherein a meta algorithm is utilized to select the plurality of scanpath predictor algorithms.

9. The image processing method of claim 1, wherein the scanpath data is obtained from an eye-tracking device that tracks eye movements of a viewer of an image corresponding to the original image data.

10. The image processing method of claim 1, wherein the image processing method is implemented in a processor of a digital camera.

11. The image processing method of claim 1, wherein the image processing method is implemented in a computing device.

12. The image processing method of claim 1, wherein there are plural sets of tone-mapping parameters, and wherein each set of tone-mapping parameters is determined by application of a lowpass filter to the original image data so as to reduce the dynamic range of the original image data.

13. The image processing method of claim 1, wherein the tone-mapping parameters are non-linear.

14. The image processing method of claim 1, wherein the tone-mapping parameters are utilized by a tone-mapping algorithm to map the tone values.

15. The image processing method of claim 1, wherein the tone-mapping parameters are utilized by a look up table to map the tone values.

16. The image processing method of claim 1, wherein the tone-mapping parameters are determined based on tone characteristics of an output medium.

17. The image processing method of claim 1, wherein the tone-mapping parameters are based on potential viewing environment characteristics.

18. The image processing method of claim 1, wherein each set of tone-mapping parameters are determined based on tonal zones of the corresponding region of interest.

19. The image processing method of claim 1, wherein the tone values are mapped by applying a tone-mapping scale to all of the original image data.

20. The image processing method of claim 1, wherein the tone values are mapped by applying a tone-mapping scale to each region of interest.

21. The image processing method of claim 1, wherein tentative-lightness image data is derived from the original image data, and the scanpath data is obtained from the tentative-lightness image data.

22. The image processing method of claim 21, wherein the original image data is RGB image data and the tentative-lightness data is based on NTSC-weighting of the RGB image data.

23. The image processing method of claim 7, wherein the aggregation of scanpath data is a weighted-average obtained based on an amount of time spent by a viewer on a location of the original image, corresponding to the original image data.

25. A computer readable memory medium on which computer executable process steps are stored, said computer readable process steps for processing image data, the computer executable process steps comprising steps to perform a method according to any one of claims 1 to 11 or 12 to 24.

26. Computer-executable process steps stored on a computer readable medium, said computer-executable process steps for processing image data, the computer-executable process steps comprising process steps executable to perform a method according to any one of claims 1 to 11 or 12 to 24.

27. A computing device for processing image data, the computing device comprising:

a program memory for storing process steps executable to perform a method according to any one of claims 1 to 11 or 12 to 24; and

a processor for executing the process steps stored in said program memory.

24. An image processing method for processing image data, the method comprising the steps of:

filtering original image data corresponding to an image to obtain filtered image data;

obtaining scanpath data corresponding to the filtered image data by using a meta algorithm which analyzes a plurality of scanpath algorithms, which selects at least two of the scanpath algorithms based on the filtered image data, and which generates a weighted average of scanpath data obtained from each of the selected scanpath algorithms;

determining a plurality of regions of interest for the original image data based on the obtained scanpath data;

determining a set of tone-mapping parameters for each of the determined regions of interest; and

mapping, with a tone-mapping algorithm, the tone values of the original image data for each region of interest based on the corresponding set of tone-mapping parameters in order to obtain tone-mapped image data.