Method of, and apparatus for image enhancement taking ambient illuminance into account

• US 7,995,851 B2
• Filed: 02/15/2006
• Issued: 08/09/2011
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Kwak, Young-Shin, Bastakov, Vladmir, Rozhkova, Galina, Kim, Chang-veong, Lebedev, Dmitry, Lee, Seong-deok
• Primary Examiner(s): Bali; Vikkram
• Assistant Examiner(s): ENTEZARI, MICHELLE M
• Application Number:
  US11/353,955
• Publication Number:
  US 20060187242A1
• Time in Patent Office: 2,001 Days
• Field of Search: None
• US Class Current: 382/254
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

A method of and an apparatus for image enhancement taking ambient illuminance into consideration. The image enhancement method includes calculating an original-luminance contrast which is a luminance contrast with respect to an original-luminance of pixels forming an original image, calculating a fade-luminance by reflecting the variation of perceived luminance based on an ambient illuminance into the original-luminance, calculating a defade-luminance by converting the fade-luminance to maintain the original-luminance contrast, and calculating a display-luminance by reflecting the variation of perceived luminance by the ambient illuminance into the defade-luminance. Improving luminance contrast through adjustment of luminance based on ambient illuminance, effectively reduces the fade phenomenon.

Claims

1. An image enhancement method, comprising:

calculating an original-luminance contrast which is a luminance contrast between an original-luminance of pixels forming an original input image;

calculating a fade-luminance by reflecting a variation of perceived luminance based on an ambient illuminance into the original-luminance;

calculating a defade-luminance by using the original-luminance contrast and a fade-average luminance with respect to the calculated fade-luminance to maintain the original-luminance contrast; and

calculating a display-luminance for displaying an output image by reflecting the variation of luminance as perceived by the ambient illuminance, into the defade-luminance.

2. The image enhancement method of claim 1, wherein the calculating of the defade-luminance comprises:

calculating the fade-average luminance by using the fade-luminance and the fade-luminance values with respect to neighboring pixels;

adding the original-luminance contrast and a predetermined weight; and

multiplying the fade-average luminance by a result of the adding, and outputting a result of the multiplying as the defade-luminance.

3. The image enhancement method of claim 2, wherein the predetermined weight is ‘

1’

.

4. The image enhancement method of claim 2, wherein the calculating of the defade-luminance further comprises:

limiting the defade-luminance within a predetermined luminance range.

5. The image enhancement method of claim 4, wherein:

when the defade-luminance is less than a first sum, which is the sum of an ambient luminance corresponding to the ambient illuminance and a predetermined lowest luminance, the limiting of the defade-luminance comprises changing the defade-luminance to the first sum, and

when the defade-luminance exceeds a second sum, which is the sum of the ambient luminance corresponding to the ambient illuminance and a predetermined highest luminance, the limiting of the defade-luminance comprises changing the defade-luminance to the second sum.

6. The image enhancement method of claim 1, wherein the calculating of the display-luminance comprises:

subtracting the ambient luminance corresponding to the ambient illuminance from the defade-luminance and outputting the result of the subtracting as the display-luminance.

7. The image enhancement method of claim 1, wherein the calculating of the original-luminance contrast comprises:

calculating an original-average luminance by using the original-luminance and original-luminance values with respect to neighboring pixels;

calculating an original-luminance difference by subtracting the original-average luminance from the original-luminance; and

dividing the original-luminance difference by the original-average luminance, and outputting the result of the dividing as the original-luminance contrast.

8. The image enhancement method of claim 1, wherein the calculating of the fade-luminance comprises:

converting the ambient illuminance, as being input, into a corresponding ambient luminance;

adding the ambient luminance and the original-luminance; and

outputting the result of the adding as the fade-luminance.

9. The image enhancement method of claim 8, wherein the calculating of the fade-luminance further comprises:

inputting a value corresponding to the ambient illuminance.

10. The image enhancement method of claim 8, wherein the calculating of the fade-luminance further comprises:

sensing the ambient illuminance to input the ambient illuminance value.

11. An image enhancement apparatus, comprising:

an original-luminance contrast calculation part calculating an original-luminance contrast which is a luminance contrast between an original-luminance of pixels forming an original input image;

a fade-luminance calculation part calculating a fade-luminance by reflecting a variation of luminance as perceived based on an ambient illuminance into the original-luminance;

a defade-luminance calculation part calculating a defade-luminance by using the original-luminance contrast and a fade-average luminance with respect to the fade-luminance, which is calculated by the fade-luminance calculation part, to maintain the original-luminance contrast which is calculated by the original-luminance contrast calculation part; and

a display-luminance calculation part calculating a display-luminance for displaying an output image by reflecting the variation of luminance as perceived by the ambient illuminance into the defade-luminance calculated by the defade-luminance calculation part.

12. The image enhancement apparatus of claim 11, wherein the defade-luminance calculation part comprises:

a low pass filter (LPF) calculating the fade-average luminance by using the fade-luminance calculated by the fade-luminance calculation part and fade-luminance values with respect to neighboring pixels;

an adding part adding the original-luminance contrast calculated by the original-luminance contrast calculation part and a predetermined weight; and

a multiplying part multiplying the fade-average luminance calculated by the LPF by the result of adding t, and outputting the result of multiplication as the defade-luminance.

13. The image enhancement apparatus of claim 12, wherein the predetermined weight is ‘

1’

.

14. The image enhancement apparatus of claim 12, wherein the defade-luminance calculation part further comprises a limiting part limiting the defade-luminance within a predetermined luminance range.

15. The image enhancement apparatus of claim 14, wherein:

when the defade-luminance is less than a first sum, which is the sum of ambient luminance corresponding to the ambient illuminance and a predetermined lowest luminance, the limiting part limits the defade-luminance to the first sum, and

when the defade-luminance exceeds a second sum, which is the sum of the ambient luminance corresponding to the ambient illuminance and a predetermined highest luminance, the limiting part limits the defade-luminance to the second sum.

16. The image enhancement apparatus of claim 11, wherein the display-luminance calculation part subtracts the ambient luminance corresponding to the ambient illuminance from the defade-luminance, and outputs the result of the subtracting as the display-luminance.

17. The image enhancement apparatus of claim 11, wherein the original-luminance contrast calculation part comprises:

a low pass filter (LPF) calculating an original-average luminance by using the original-luminance and original-luminance values with respect to neighboring pixels;

a subtracting part calculating an original-luminance difference by subtracting and the original-average luminance which is calculated by the LPF from the original-luminance; and

a dividing part dividing the original-luminance difference calculated by the subtracting part, by the original-average luminance calculated by the LPF, and outputting the result of division as the original-luminance contrast.

18. The image enhancement apparatus of claim 11, wherein the fade-luminance calculation part comprises:

a converting part converting the ambient illuminance as being inputted, into a corresponding ambient luminance; and

an adding part adding the external luminance converted by the converting part, with the original-luminance, and outputting the result of adding as the fade-luminance.

19. The image enhancement apparatus of claim 18, further comprising:

an ambient illuminance sensing part sensing the ambient illuminance of the apparatus and inputs and inputting the ambient illuminance to the converting part.

20. The image enhancement apparatus of claim 18, further comprising:

an ambient illuminance input part operable by a user to input a value corresponding to the ambient illuminance to the converting part.