# US 12,217,724 B2 · Perceptual luminance nonlinearity-based image data exchange across different display capabilities

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- Number: US 12,217,724 B2
- Document ID: US12217724B2
- Status: Granted
- Kind: B2
- Application number: 18/542,921
- Filed: 2023-12-18
- Published: 2024-05-02
- Granted: 2025-02-04
- Earliest claimed: 2011-12-06
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Jon Scott Miller; Scott Daly; Mahdi Nezamabadi; Robin Atkins
- Web page: https://patentgrep.com/patent/US12217724B2

## CPC

- G09G 5/10: Intensity circuits
- G06F 3/14: Digital output to display device {; Cooperation and interconnection of the display device with other functional units}
- G09G 5/005: {Adapting incoming signals to the display format of the display terminal}
- G09G 5/06: using colour palettes, e.g. look-up tables
- H04N 19/40: using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
- G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
- G09G 2320/0285: using tables for spatial correction of display data
- G09G 2320/04: Maintaining the quality of display appearance
- G09G 2340/0428: Gradation resolution change
- G09G 2340/0435: Change or adaptation of the frame rate of the video stream
- G09G 2340/06: Colour space transformation
- G09G 2340/14: Solving problems related to the presentation of information to be displayed
- G09G 2370/04: Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
- G09G 2370/08: Details of image data interface between the display device controller and the data line driver circuit
- G09G 2380/08: Biomedical applications
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## 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.

## Claims

### Claim 1

An apparatus for encoding image data, the apparatus comprising:
an input to receiving image data with luminance values representing absolute luminance values L to be encoded; and
a processor, wherein the processor:
encodes the image data into reference encoded image data; and
outputs the reference encoded image data,
wherein the encoding comprises mapping absolute luminance values into digital code values, the luminance values of the received image data being represented by the digital code values in the reference encoded image data;
wherein the mapping is based at least in part on an inverse of a functional model of:
Y
=
(
max
[
(
V
1
/
m
-
c
1
)
,
0
]
c
2
-
c
3
⁢
V
1
/
m
)
1
/
n
,
wherein:
Y is a normalized value of a corresponding one of the absolute luminance values L, wherein 0≤Y≤1,
V is a normalized value of a corresponding one of the digital code values D that are output as reference encoded image data, wherein 0≤V≤1, and
n, m, c1, c2, and c3 are predetermined values, with:
n
=
2610
4
⁢
0
⁢
9
⁢
6
×
1
4
≃
0.1593017578125
;
m
=
2
⁢
5
⁢
2
⁢
3
4
⁢
0
⁢
9
⁢
6
×
128
≃
78.84375
;
c
1
=
c
3
-
c
2
+
1
=
3
⁢
4
⁢
2
⁢
4
4
⁢
0
⁢
9
⁢
6
≃
0.8359375
;
c
2
=
2
⁢
4
⁢
1
⁢
3
4
⁢
0
⁢
9
⁢
6
×
32
≃
18.8515655
;
and
⁢
c
3
=
2
⁢
3
⁢
9
⁢
2
4
⁢
0
⁢
9
⁢
6
×
32
-
18.6875
.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the digital code values D are 8, 10, or 12 bits code values.

### Claim 3

An apparatus for decoding a bitstream, the apparatus comprising:
an input for receiving encoded image data; and
a processor, wherein the processor:
decodes the image data, characterized in that the decoding comprises mapping digital code values in the encoded image data to normalized luminance values based at least in part on a functional model of:
Y
=
(
max
[
(
V
1
/
m
-
c
1
)
,
0
]
c
2
-
c
3
⁢
V
1
/
m
)
1
/
n
,
wherein:
Y is a normalized luminance value, wherein 0≤Y≤1,
V is a normalized value of a corresponding one of the digital code values D of the encoded image data, wherein 0≤V≤1, and
n, m, c1, c2, and c3 are predetermined values, with:
n
=
2610
4
⁢
0
⁢
9
⁢
6
×
1
4
≃
0.1593017578125
;
m
=
2
⁢
5
⁢
2
⁢
3
4
⁢
0
⁢
9
⁢
6
×
128
≃
78.84375
;
c
1
=
c
3
-
c
2
+
1
=
3
⁢
4
⁢
2
⁢
4
4
⁢
0
⁢
9
⁢
6
≃
0.8359375
;
c
2
=
2
⁢
4
⁢
1
⁢
3
4
⁢
0
⁢
9
⁢
6
×
32
≃
18.8515655
;
and
⁢
c
3
=
2
⁢
3
⁢
9
⁢
2
4
⁢
0
⁢
9
⁢
6
×
32
-
18.6875
.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein the digital code values D are 8, 10, or 12 bits code values.