DYNAMIC RANGE-ADJUSTMENT APPARATUSES AND METHODS

• US 20140348428A1
• Filed: 05/24/2013
• Published: 11/27/2014
• Est. Priority Date: 05/24/2013
• Status: Abandoned Application

• Current Assignee: Himax Media Solutions, Inc. (Himax Technologies Incorporated)
• Original Assignee: Himax Media Solutions, Inc. (Himax Technologies Incorporated)
• Inventors: Lee, Kun-Hsien
• Application Number:
  US13/902,002
• Publication Number:
  US 20140348428A1
• Time in Patent Office: Days
• US Class Current: 382/169
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/92 based on global image properties

Abstract

A dynamic range-adjustment apparatus is provided. The apparatus includes: an input unit for receiving an original image; an histogram equalization unit, coupled to the input unit, for performing contrast enhancement on the original image to produce a contrast-enhanced image; a factor-determination unit, coupled to the input unit and the histogram equalization unit, for determining a first factor based on the gray level of a pixel of the original image and the tone of the corresponding pixel of the contrast-enhanced image; and an adjustment unit, coupled to the input unit, the histogram equalization unit and the factor-determination unit.

Claims

1. A dynamic range-adjustment apparatus, comprising:

an input unit for receiving an original image;

an histogram equalization unit, coupled to the input unit, for performing contrast enhancement on the original image to produce a contrast-enhanced image;

a factor-determination unit, coupled to the input unit and the histogram equalization unit, for determining a first factor based on the gray level of a pixel of the original image and the tone of the corresponding pixel of the contrast-enhanced image; and

an adjustment unit, coupled to the input unit, the histogram equalization unit and the factor-determination unit, for blending the original image and the contrast-enhanced image based on the first factor.

2. The dynamic range-adjustment apparatus as claimed in claim 1, wherein the adjustment unit blends the original image and the contrast-enhanced image according to the following formula:

final_value=α

×

original_value+(1−

α

)×

modified_value,

wherein the symbols “

final_value”

, “

original_value”

, and “

modified_value”

respectively represent the brightness values of the final image, the original image, and the contrast-enhanced image; and

the symbol “

α

”

represents the first factor.

3. The dynamic range-adjustment apparatus as claimed in claim 1, wherein the input unit further comprises a data-format converter.

4. The dynamic range-adjustment apparatus as claimed in claim 3, wherein the data-format converter is a RGB-HSV converter.

5. The dynamic range-adjustment apparatus as claimed in claim 1, wherein the factor-determination unit further comprises:

a gray-level detector for detecting the gray level of the pixel of the original image.

6. The dynamic range-adjustment apparatus as claimed in claim 1, wherein the factor-determination unit further comprises:

a region divider for dividing the histogram of the contrast-enhanced image into a plurality of regions.

7. The dynamic range-adjustment apparatus as claimed in claim 6, wherein the factor-determination unit further comprises:

a tone detector for calculating the tone of the pixel of the contrast-enhanced image, and the tone of the pixel of the contrast-enhanced image is defined as follows;

tone=(gray_value−

region_bottom)/(region_upper−

region_bottom),

wherein the symbol “

gray_value”

represents the gray level of the pixel of the original image; and

the “

region_upper” and

the “

region_bottom”

respectively represent the upper and bottom limits of the region where the pixel is located.

8. The dynamic range-adjustment apparatus as claimed in claim 7, wherein the factor-determination unit further comprises:

a factor calculator for calculating the first factor according to the following formula;

α

=tone×

(gray_max−

gray_value)/(gray_upper−

gray_bottom)

wherein the symbol “

gray_max”

represents the maximum gray value of all the pixels of the original image; and

the symbol “

gray_upper” and

“

gray_bottom”

respectively represent the upper and bottom limits of the gray-level range.

9. The dynamic range-adjustment apparatus as claimed in claim 1, further comprising a light sensor for sensing the light intensity of the external environment.

10. The dynamic range-adjustment apparatus as claimed in claim 9, wherein the factor-determination unit determines a second factor β

according to the light intensity sensed by the light sensor.

11. The dynamic range-adjustment apparatus as claimed in claim 10, wherein the adjustment unit blends the original image and the contrast-enhanced image according to the following formula:

final_value=β

×

original_value+(1−

β

)×

[α

×

original_value+(1−

α

)×

modified_value]

wherein the symbols “

final_value”

, “

original_value”

, and “

modified_value”

respectively represent the brightness values of the final image, the original image, and the contrast-enhanced image;

the symbol “

α

”

represents the first factor; and

the symbol “

β

”

represents the second factor.

12. A dynamic range-adjustment method, comprising the steps of:

receiving an original image;

performing contrast enhancement on the original image to produce a contrast-enhanced image;

determining a first factor based on the gray level of a pixel of the original image and the tone of the corresponding pixel of the contrast-enhanced image; and

blending the original image and the contrast-enhanced image based on the first factor.

13. The dynamic range-adjustment method as claimed in claim 12, wherein the original image and the contrast-enhanced image are blended according to the following formula:

final_value=α

×

original_value+(1−

α

)×

modified_value,

wherein the symbols “

final_value”

, “

original_value”

, and “

modified_value”

respectively represent the brightness values of the final image, the original image, and the contrast-enhanced image; and

the symbol “

α

”

represents the first factor.

14. The dynamic range-adjustment method as claimed in claim 12, further comprising converting the data format of the original image.

15. The dynamic range-adjustment method as claimed in claim 14, wherein the data format is converted from a RGB data format to a HSV data format.

16. The dynamic range-adjustment method as claimed in claim 12, wherein the step of determining a first factor further comprises:

detecting the gray level of the pixel of the original image.

17. The dynamic range-adjustment method as claimed in claim 12, wherein the step of determining a first factor further comprises:

dividing the histogram of the contrast-enhanced image into a plurality of regions.

18. The dynamic range-adjustment method as claimed in claim 17, wherein the step of determining a first factor further comprises:

calculating the tone of the pixel of the contrast-enhanced image, and the tone of the pixel of the contrast-enhanced image is defined as follows;

tone=(gray_value−

region_bottom)/(region_upper−

region_bottom),

wherein the symbol “

gray_value”

represents the gray level of the pixel of the original image; and

the “

region_upper” and

the “

region_bottom”

respectively represent the upper and bottom limits of the region where the pixel is located.

19. The dynamic range-adjustment method as claimed in claim 18, wherein the step of determining a first factor further comprises:

calculating the first factor according to the following formula;

α

=tone×

(gray_max−

gray_value)/(gray_upper−

gray_bottom)

wherein the symbol “

gray_max”

represents the maximum gray value of all the pixels of the original image; and

the symbol “

gray_upper” and

“

gray_bottom”

respectively represent the upper and bottom limits of the gray-level range.

20. The dynamic range-adjustment method as claimed in claim 12, further comprising:

sensing the light intensity of the external environment.

determining a second factor β

according to the light intensity sensed by the light sensor; and

blending the original image and the contrast-enhanced image according to the following formula;

final_value=β

×

original_value+(1−

β

)×

[α

×

original_value+(1−

α

)×

modified_value]

wherein the symbols “

final_value”

, “

original_value”

, and “

modified_value”

respectively represent the brightness values of the final image, the original image, and the contrast-enhanced image;

the symbol “

α

”

represents the first factor; and

the symbol “

β

”

represents the second factor.