APPARATUS AND METHOD FOR PROCESSING IMAGES

• US 20090002530A1
• Filed: 06/16/2008
• Published: 01/01/2009
• Est. Priority Date: 06/27/2007
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Itoh, Yuji, Arai, Emi
• Application Number:
  US12/140,049
• Publication Number:
  US 20090002530A1
• Time in Patent Office: Days
• US Class Current: 348/294
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 23/843 Demosaicing, e.g. interpolating colour pixel values
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/585 with pixels having different sensitivities within the sensor, e.g. fast or slow pixels or pixels having different sizes

Abstract

The mixing of high-gain and low-gain outputs of a wide dynamic range image sensor uses relationship parameter estimation according to linear regression; and the mixed output is adaptively filtered for noise gap reduction.

Claims

1. A method for wide dynamic range (WDR) sensor output, comprising:

(a) providing plurality of collocated high-gain output and low-gain output pairs for pixels in an image captured by a WDR sensor;

(b) selecting a subplurality of said plurality where low-gain outputs in said subplurality are separated by multiples of an output interval and said high-gain outputs are less than a saturation value;

(c) computing by least squares a linear relationship between said high-gain outputs and said low-gain outputs for said subplurality; and

(d) mixing said high-gain outputs and said low-gain outputs of said plurality according to said linear relationship to form a WDR sensor output.

2. The method of claim 1, wherein said mixing includes a soft transition about pairs with said high-gain output within a threshold of saturation.

3. A method for wide dynamic range (WDR) sensor output, comprising:

(a) providing plurality of collocated high-gain output and low-gain output pairs for pixels in an image captured by a WDR sensor;

(b) providing a linear relationship between said high-gain outputs and said low-gain outputs;

(c) mixing said high-gain outputs and said low-gain outputs according to said linear relationship to form a WDR sensor output; and

(d) adaptively filtering said WDR sensor output, said adaptive filtering includes the steps of;

(i) indexing the pixels by comparison of the WDR sensor output for a pixel to the WDR sensor outputs for the same color pixels in a neighborhood;

(ii) for a target pixel, replacing the WDR sensor output for each pixel in a filter neighborhood of the target pixel with the WDR sensor output of the target pixel when the index of said each pixel differs from the index of the target pixel; and

(iii) linearly filtering at the target pixel; and

(iv) repeating (ii)-(iii) with the target pixel replaced by other pixels of the WDR sensor output image.