# US 9,521,419 B2 · Perceptual luminance nonlinearity-based image data exchange across different display capabilities

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- Number: US 9,521,419 B2
- Document ID: US9521419B2
- Status: Granted
- Kind: B2
- Application number: 14/925,596
- Filed: 2015-10-28
- Published: 2016-04-28
- Granted: 2016-12-13
- 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/US9521419B2

## 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}
- 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

A method comprising
receiving, by a data encoder, image data to be encoded;
accessing, via the data encoder, a reference data conversion function which determines a mapping between a set of reference digital code values and a set of reference levels based on contrast sensitivity of human vision;
based on the receiving and the accessing, encoding, via the data encoder, the received image data into reference encoded image data; and
outputting, via the data encoder, the reference encoded image data,
wherein:
color component values in the received image data are represented by the set of reference digital code values, the reference digital code values having a bit depth of 10 or 12 bits,
the mapping is based at least in part on a functional model of:
(
C
1
+
C
2
⁢
Y
n
1
+
c
3
⁢
Y
n
)
m
,
and
n, m, c1, c2, and c3 are predetermined values.

### Claim 2 (depends on 1)

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
.

### Claim 3 (depends on 1)

The method of claim 1, wherein the color component is at least one of R, G and B color components.

### Claim 4 (depends on 1)

The method of claim 1, wherein the color component is normalized luminance (Y).

### Claim 5 (depends on 1)

The method of claim 1, further comprising a step of mapping, via the data encoder, of a digital code value D in the image data to a normalized value V, wherein 0≦V≦1.

### Claim 6 (depends on 5)

The method of claim 5, wherein the digital code value D represents a sampled value of a component of the image data comprised in a serial digital interface (SDI) signal.

### Claim 7 (depends on 5)

The method of claim 5, wherein the bit depth is 10 bits and the mapping of the digital code value D to the normalized value V is provided by Table 4 of the specification.

### Claim 8 (depends on 1)

The method of claim 1, wherein the image data comprises digital code values D which represent sampled values of a component of the image data, the image data being encoded in one of a high-resolution high dynamic range (HDR) image format, a RGB color space associated with the Academy Color Encoding Specification (ACES) standard of the Academy of Motion Picture Arts and Sciences (AMPAS), a P3 color space standard of the Digital Cinema initiative, a Reference Input Medium Metric/Reference Output Medium Metric (RIMM/ROMM) standard, an sRGB color space, or a RGB color space associated with the BT.709 Recommendation standard of the International Telecommunications Union (ITU).

### Claim 9

A data encoder configured to encode received image data to reference encoded image data, the data encoder comprising:
a receiver unit receiving image data to be encoded;
a mapping unit mapping digital code values in a received image data to reference digital code values in the reference encoded image data based on contrast sensitivity of human vision;
an encoding unit encoding, based on the receiving and mapping, the image data into the reference encoded image data; and
a transmission unit transmitting the reference encoded image data;
wherein the mapping unit maps the digital code values based at least in part on a functional model of:
(
c
1
+
c
2
⁢
Y
n
1
+
c
3
⁢
Y
n
)
m
;
and
n, m, c1, c2, and c3 are predetermined values.

### Claim 10 (depends on 9)

The data encoder of claim 9, wherein:
n
=
⁢
2610
4096
⁢
⁢
x
⁢
⁢
1
4
≃
0.1593017578125
⁢
;
m
=
⁢
2523
4096
⁢
⁢
x
⁢
⁢
128
≃
78.84375
⁢
;
c
1
=
⁢
c
3
-
c
2
+
1
=
3424
4096
≃
0.8359375
⁢
;
c
2
=
⁢
2413
4096
⁢
⁢
x
⁢
⁢
32
≃
18.8515625
⁢
;
and
c
3
=
⁢
2392
4096
⁢
⁢
x
⁢
⁢
32
≃
18.6875
.

### Claim 11 (depends on 9)

The data encoder of claim 9, wherein the reference digital code values have a bit depth of 10 or 12 bits and represent color component values in the received image data.

### Claim 12 (depends on 11)

The data encoder of claim 11, wherein the color component is at least one of R, G and B color components.

### Claim 13 (depends on 11)

The data encoder of claim 11, wherein the color component is normalized luminance (Y).

### Claim 14 (depends on 11)

The data encoder of claim 11, wherein the mapping unit is further configured to map a digital code value D in the image data to a normalized value V, wherein 0≦V≦1.

### Claim 15 (depends on 14)

The data encoder of claim 14, wherein the digital code value D represents a sampled value of a component of the image data comprised in a serial digital interface (SDI) signal.

### Claim 16 (depends on 14)

The data encoder of claim 14, wherein the bit depth is 10 bits and the mapping unit maps the digital code D to the normalized value V according to a mapping scheme that is provided by Table 4 of the specification.

### Claim 17 (depends on 14)

The data encoder of claim 14, wherein the mapping unit is further configured to exclude at least a lowest three and a highest three reference digital code values from the mapping.

### Claim 18 (depends on 17)

The data encoder of claim 17, wherein a relationship between the normalized 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.