Method of processing brightness of an image and related device

• US 7,738,727 B2
• Filed: 08/14/2006
• Issued: 06/15/2010
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: Novatek Microelectronics Corporation (Novatek Microelectronics Corp Limited)
• Original Assignee: Novatek Microelectronics Corporation (Novatek Microelectronics Corp Limited)
• Inventors: Liu, Ming-Chang, Lu, Fang-Mei, Chang, Rei-Hong
• Primary Examiner(s): Kassa; Yosef
• Application Number:
  US11/464,483
• Publication Number:
  US 20070223814A1
• Time in Patent Office: 1,401 Days
• Field of Search: 382/260, 382/274, 382/275, 358/3.26, 358/3.27, 358/463
• US Class Current: 382/274
• CPC Class Codes: G06T 2207/20182 Noise reduction or smoothing in the temporal domain; Spatio-temporal filtering
• CPC Class Codes: G06T 5/92 based on global image properties

Abstract

Brightness values of image frames are collected and counted to form a brightness distribution. The brightness distribution of the image frames is compared with predetermined brightness distributions. Brightness values of all pixels of successive image frames are adjusted according to a result of the comparison, so as to improve image contrast.

Claims

1. A method for processing brightness of an image comprising:

generating a plurality of predetermined brightness distributions each comprising a number of pixels whose brightness value is within each of a plurality of predetermined brightness intervals;

generating a brightness distribution of a plurality of pixels of the image according to brightness values of the pixels;

a brightness comparator comparing the brightness distribution of the pixels with each of the predetermined brightness distributions for determining whether a difference between the brightness distribution of the pixels and one of the predetermined brightness distributions is within a predetermined range; and

when the difference between the brightness distribution of the pixels and the one of the predetermined brightness distributions is within the predetermined range, a brightness gain unit adjusting brightness values of upcoming pixels according to a transformation rule corresponding to the one of the predetermined brightness distribution.

2. The method of claim 1 wherein generating the brightness distribution of the plurality of pixels according to the brightness values of the pixels comprises calculating a number of pixels whose brightness value is within a predetermined brightness interval.

3. The method of claim 2 wherein determining whether the difference between the brightness distribution of the pixels and the predetermined brightness distributions is within the predetermined range comprises:

determining whether the difference between the brightness distribution of the pixels and the one of the predetermined brightness distributions is within a predetermined range according to an equation

$D\ge <br><br>\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br><br><br>A-B<br><br>;<br><br><br><br>\mathrm{wherein}$

D is the predetermined range;

A is number of brightness values within an interval i of the brightness distribution of the pixels;

B is value of the one of the predetermined brightness distribution corresponding to the interval i; and

n is number of the intervals of the brightness distribution.

4. The method of claim 1 wherein adjusting the brightness values of the upcoming pixels according to the transformation rule comprises using a transformation function to transform the brightness values of the upcoming pixels.

5. The method of claim 1 wherein adjusting the brightness values of the upcoming pixels according to the transformation rule comprises adjusting the brightness values of the upcoming pixels according to a look-up table.

6. The method of claim 1 wherein generating the brightness distribution of the pixels comprises collecting data on brightness values of a plurality of pixels of an image.

7. The method of claim 1 wherein generating the brightness distribution of the pixels comprises collecting data on brightness values of pixels of a plurality of images.

8. An image processor for adjusting a brightness of images, the image processor comprising:

a brightness comparator for comparing a brightness distribution of a plurality of pixels with each of a plurality of predetermined brightness distributions; and

a brightness gain unit for adjusting gains of brightness values of pixels of an upcoming image according to a transformation rule corresponding to one of the predetermined brightness distributions with which the brightness distribution of the pixels compares;

wherein the brightness distribution of the plurality of pixels comprises a number of pixels whose brightness value is within each of a plurality of predetermined brightness intervals.

9. The image processor of claim 8 further comprising a brightness accumulation memory unit for accumulating brightness values of the pixels.

10. The image processor of claim 9 further comprising a timing accumulation memory unit for controlling the brightness accumulation memory unit to accumulate the brightness values of the pixels.

11. The image processor of claim 8 further comprising a static random access memory (SRAM) for storing the predetermined brightness distributions.

12. The image processor of claim 8 further comprising a static random access memory (SRAM) for storing the transformation rule.