METHOD OF PROCESSING BRIGHTNESS OF AN IMAGE AND RELATED DEVICE

• US 20070223814A1
• Filed: 08/14/2006
• Published: 09/27/2007
• 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, Chang, Rei-Hong, Lu, Fang-Mei
• Granted Patent: US 7,738,727 B2
• Time in Patent Office: Days
• US Class Current: 382/169
• CPC Class Codes: G06T 2207/20182 Noise reduction or smoothing in the temporal domain; Spatio-temporal filtering
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• 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 brightness distribution of a plurality of pixels of the image according to brightness values of the pixels;

determining whether a difference between the brightness distribution of the pixels and a predetermined brightness distribution is within a predetermined range; and

if the difference between the brightness distribution of the pixels and the predetermined brightness distribution is within the predetermined range, adjusting brightness values of upcoming pixels according to a transformation rule corresponding to 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 distribution is within the predetermined range comprises:

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

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

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 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 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.

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.