System and method for creating an image with a wide dynamic range

1. A system for creating an image with a wide dynamic range, the system comprising:

an imaging unit configured to acquire a plurality of images of a scene at respective exposure times such that each of the respective exposure times are different from one another;

a processing unit and a control unit operatively connected to the imaging unit and to each other;

wherein the plurality of images are each represented by respective sets of pixels defining respective pixel intensities, each pixel in the respective sets of pixels being identifiable by a two-dimensional coordinate;

wherein the processing unit is configured to combine the plurality of images to produce a combined image represented by a set of combined pixels;

wherein for each of the two-dimensional coordinates the processing unit is configured to:

receive the respective pixel intensities for each of the plurality of images from the imaging unit;

assign a respective weighting factor to the respective sets of pixels in each of the plurality of images;

obtain a respective combined intensity value for the set of combined pixels at each of the two-dimensional coordinates;

convert the respective combined intensity values into respective mapped values using a mapping graph, the respective mapped values being used to generate the combined image; and

wherein a first portion of the mapping graph is a linear scale and a second portion of the mapping graph is a logarithmic scale.

2. The system of claim 1 , wherein the imaging unit is a digital camera.

3. The system of claim 1 , wherein the control unit is configured to:

set a first exposure time to a first predetermined value and direct the imaging unit to acquire a first of the plurality of images using the first exposure time;

set a second exposure time to a second predetermined value and direct the imaging unit to acquire a second of the plurality of images at the second exposure time;

determine if a sufficient number of images have been obtained based on whether a predefined condition is satisfied; and

obtain additional images if the predefined condition is not satisfied.

4. The system of claim 3 , wherein the predefined condition is satisfied when at least 20% of the respective pixel intensities of the first and second of the plurality of images have reached a saturated value.

5. The system of claim 3 , wherein the second exposure time is a constant multiplier of the first exposure time.

6. The system of claim 3 , wherein the control unit is further configured to:

set a third exposure time to a third predetermined value and direct the imaging unit to acquire a third of the plurality of images at the third exposure time if the predefined condition is not satisfied.

7. The system of claim 6 , wherein the first exposure time is 2.5 milliseconds; the second exposure time is 10 milliseconds and the third exposure time is 40 milliseconds.

8. The system of claim 1 , wherein for each of the plurality of images:

the control unit defines a maximum allowed pixel value for each of the respective pixel intensities;

the respective weighting factor is set as the respective exposure time if the respective pixel intensity is below the maximum allowed pixel value; and

the respective weighting factor is set as zero if the respective pixel intensity is at the maximum allowed pixel value.

9. The system of claim 1 , wherein the obtaining a respective combined intensity value for each of the set of combined pixels includes:

determining a first value for each of the plurality of images as a product of the respective pixel intensities and the respective weighting factors, divided by the respective exposure time;

determining a second value by adding the first value for each of the plurality of images;

obtaining the respective combined intensity value by dividing the second value by a sum of the respective weighting factors for each of the plurality of images.

10. The system of claim 1 , wherein the control unit is configured to:

determine if a sum of the respective weighting factors for each of the plurality of images is zero; and

set the respective combined intensity value as a maximum allowable pixel value if the sum of the respective weighting factors is zero.

11. The system of claim 1 , wherein the first portion of the mapping graph is applied to respective pixel intensities that are less than 3% of a maximum allowed pixel value.

12. The system of claim 1 , wherein the imaging unit, the control unit and the processing unit are part of a single device.

13. The system of claim 1 , wherein the processing unit includes at least one AND logic gate, at least two memory units, at least one comparator unit and at least one divider unit.

14. A method of creating a wide dynamic range image, the method comprising:

acquiring a plurality of images of a scene at a plurality of respective exposure times, respectively, each of the plurality of respective exposure times being different from one another;

wherein the plurality of images are each represented by respective sets of pixels defining respective pixel intensities, each pixel in the respective sets of pixels being identifiable by a two-dimensional coordinate;

assigning a respective weighting factor to each of the respective pixel intensities in each of the plurality of images;

obtaining a respective combined intensity value at each of the two-dimensional coordinates;

wherein the obtaining of the respective combined intensity values includes:

determining a first value for each of the plurality of images as a product of the respective pixel intensities and the respective weighting factors, divided by the respective exposure time

determining a second value by adding the first value for each of the plurality of images; and

obtaining the respective combined intensity value by dividing the second value by a sum of the respective weighting factors for each of the plurality of images;

converting the respective combined intensity values into respective mapped values using a mapping graph; and

generating a combined image using the respective mapped values.

15. A system for creating an image with a wide dynamic range, the system comprising:

an imaging unit configured to acquire a plurality of images of a scene at respective exposure times such that each of the respective exposure times are different from one another;

a processing unit and a control unit operatively connected to the imaging unit and to each other;

wherein the plurality of images are each represented by respective sets of pixels defining respective pixel intensities, each pixel in the respective sets of pixels being identifiable by a two-dimensional coordinate;

wherein the processing unit is configured to combine the plurality of images to produce a combined image represented by a set of combined pixels;

wherein for each of the two-dimensional coordinates the processing unit is configured to:

receive the respective pixel intensities for each of the plurality of images from the imaging unit;

assign a respective weighting factor to the respective sets of pixels in each of the plurality of images;

obtain a respective combined intensity value for the set of combined pixels at each of the two-dimensional coordinates;

convert the respective combined intensity values into respective mapped values using a mapping graph, the respective mapped values being used to generate the combined image; and

determine a sum of the respective weighting factors for each of the plurality of images.

16. The system of claim 15 , wherein the control unit is configured to set the respective combined intensity value as a maximum allowable pixel value if the sum of the respective weighting factors is zero.

17. The system of claim 15 , wherein the obtaining a respective combined intensity value for each of the set of combined pixels includes:

determining a first value for each of the plurality of images as a product of the respective pixel intensities and the respective weighting factors, divided by the respective exposure time;

determining a second value by adding the first value for each of the plurality of images; and

obtaining the respective combined intensity value by dividing the second value by a sum of the respective weighting factors for each of the plurality of images.

18. The system of claim 15 , wherein the control unit is configured to:

set a first exposure time to a first predetermined value and direct the imaging unit to acquire a first of the plurality of images using the first exposure time;

set a second exposure time to a second predetermined value and direct the imaging unit to acquire a second of the plurality of images at the second exposure time;

determine if a sufficient number of images have been obtained based on whether a predefined condition is satisfied; and

obtain additional images if the predefined condition is not satisfied.

19. The system of claim 18 , wherein the second exposure time is a constant multiplier of the first exposure time.