Digital still camera system and method

• US 20020135683A1
• Filed: 12/20/2000
• Published: 09/26/2002
• Est. Priority Date: 12/20/1999
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Yamauchi, Satoru, Osamoto, Akira, Koshiba, Osamu, Tamama, Hideo
• Application Number:
  US09/742,258
• Publication Number:
  US 20020135683A1
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: G06T 1/60 Memory management
• CPC Class Codes: G06T 3/4015 Image demosaicing, e.g. colour filter arrays [CFA] or Bayer patterns
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: H04N 1/212 Motion video recording combined with still video recording television signal recording H04N5/76
• CPC Class Codes: H04N 1/4074 using histograms
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• 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 25/136 using complementary colours
• CPC Class Codes: H04N 5/77 between a recording apparatus and a television camera
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure
• CPC Class Codes: H04N 5/907 using static stores, e.g. storage tubes or semiconductor memories H04N5/91 takes precedence
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

A tone-scaling in a digital image with pixel intensities replaced by a linear combination of pixel intensities and cumulative intensity distribution values.

Claims

1. A method of tone-scaling an image, comprising the steps of:

(a) providing an M by N pixel image where M and N are positive integers and each pixel has an intensity in the range from 0 to K;

(b) determining a scaled cumulative distribution function T(X) for X in the range 0 to K and T(X) with values in the range 0 to K, wherein T(X) equals K multiplied by the number of the pixels in the image with intensity less than or equal to X and then divided by MN;

(c) selecting a parameter A in the range 0 to 1;

(d) adjusting the intensity of a pixel of the image of step (a) from Z to AT(Z)+(1−

A)Z.

2. The method of claim 1, wherein:

(a) the intensities of the image of step (a) of claim 1 are integer valued; and

(b) the adjusted intensity of step (d) is rounded off to the nearest integer value.

3. The method of claim 1, wherein:

(a) the intensity of a pixel of the image of step (a) of claim 1 is the luminance of the pixel.

4. The method of claim 3, wherein:

(a) the parameter A has a value about 0.3.

5. A tone-scaler, comprising:

(a) a scaled cumulative distribution function lookup table;

(b) a parameter input, with the parameter in the range 0 to 1, including endpoints;

(c) a converter coupled to said lookup table and parameter input, said converter replacing a pixel intensity Z with AT(Z)+(1−

A)Z where A is said parameter and T(Z) the lookup table value for Z.

6. The tone-scaler of claim 5, wherein:

(a) the lookup table is T(X) for an M by N pixel image where M and N are positive integers and each pixel has an intensity X in the range from 0 to K and T(X) has values in the range 0 to K, wherein T(X) equals K multiplied by the number of the pixels in the image with intensity less than or equal to X and then divided by MN.

7. A tone-scaler, comprising:

(a) a processor programmed to

(i) determine a scaled cumulative distribution function T(X) for an M by N pixel image where M and N are positive integers and each pixel has an intensity X in the range from 0 to K and T(X) has values in the range 0 to K, wherein T(X) equals K multiplied by the number of the pixels in the image with intensity less than or equal to X and then divided by MN; and

(ii) adjust the intensity of a pixel of the image of (i) from Z to AT(Z)+(1 −

A)Z wherein A is a parameter in the range 0 to 1.