Perceptual luminance nonlinearity-based image data exchange across different display capabilities

Patent metadata

Field	Value
Publication number	US-11600244-B2
Application number	US-202217892473-A
Country	US
Kind code	B2
Filing date	Aug 22, 2022
Priority date	Dec 6, 2011
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

First claim

It is claimed:

1. A method comprising:
determining an absolute luminance value L for an image;
determining a normalized luminance value Y from an absolute luminance value L;
computing a normalized perceptual curve signal value V from a normalized luminance value Y based on a functional model of

V
=

(

c
1

+

c
2

⁢

Y
n

1
+

c
3

⁢

Y
n

)

m

;

and
representing the normalized perceptual curve signal value V as a digital code value D, wherein the digital code value D excludes reserved code values, and
parameters n, m, C 1 , C 2 , and C 3 are predetermined values.

2. The method of claim 1 , wherein

Y
=

L

10

,
TagBox[",", "NumberComma", Rule[SyntaxForm, "0"]]

000

.

3. The method of claim 1 , wherein:

n
=

2610
4096

×

1
4

≃
0.1593017578125

;

m
=

2523
4096

×
128

≃
78.84375

;

c
1

=

c
3

-

c
2

+
1

=

3424
4096

≃
0.8359375

;

c
2

=

2413
4096

×
32

≃
18.8515625

;
and

c
3

=

2392
4096

×
32

≃

18.6875
.

4. The method of claim 1 , wherein the digital code value D has a bit depth b of 10 bits.

5. The method of claim 1 , wherein the digital code value D has a bit depth b of 12 bits.

6. The method of claim 1 , wherein a relationship between the normalized perceptual curve signal value V and the digital code value D is provided by the function:

V
=

D
-

4
·

2

b
-
10

1015
·

2

b
-
10

wherein b is a bit depth corresponding to a number of bits used to represent the digital code value.

7. The method of claim 1 further comprising storing the digital code value D on a non-transitory storage media.

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Miller Jon Scott
• Daly Scott
• Nezamabadi Mahdi
• Atkins Robin

Classifications

• G09G5/10 Primary

  Intensity circuits · CPC title

• G09G5/005

  Adapting incoming signals to the display format of the display terminal · CPC title

• G09G2340/0428

  Gradation resolution change · CPC title

• H04N19/40

  using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream · CPC title

• G09G5/06

  using colour palettes, e.g. look-up tables · CPC title