# US 2014/0198126 A1 · Methods and apparatus for reduced low-tone half-tone pattern visibility

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0198126 A1
- Document ID: US20140198126A1
- Status: Published application
- Kind: A1
- Application number: 13/742,872
- Filed: 2013-01-16
- Published: 2014-07-17
- Earliest claimed: 2013-01-16
- Assignees: QUALCOMM MEMS Technologies, Inc.
- Applicants: Qualcomm Mems Technologies, Inc.
- Inventors: Manu Parmar; Jeho Lee
- Web page: https://patentgrep.com/patent/US20140198126A1

## CPC

- G09G 3/2044: {using dithering}
- H04N 1/40087: {Multi-toning, i.e. converting a continuous-tone signal for reproduction with more than two discrete brightnesses or optical densities, e.g. dots of grey and black inks on white paper}
- H04N 1/4052: {by error diffusion, i.e. transferring the binarising error to neighbouring dot decisions}
- 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)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

This disclosure provides methods, apparatus, and computer programs encoded on computer storage media for reduced low tone pattern visibility. In one aspect, the disclosed methods receive an input image including a plurality of pixels, quantize the plurality of pixels, set half-tone image pixels corresponding to the portion of the input pixels that are below a crush threshold to a crushed value, and diffuse the quantization error resulting from the quantizing to half-tone image pixels other than the portion. In some implementations, the half-tone image pixels are then output to an output device such as an electronic display.

## Claims

### Claim 1

A method of rendering at least a portion of a half-tone image on a display, the method comprising:
receiving an input image including a plurality of input pixels;
dithering at least a portion of the input pixels;
setting half-tone image pixels corresponding to the portion of the input pixels that are below a crush threshold to a crushed value; and
outputting the half-tone image pixels to an output device.

### Claim 2 (depends on 1)

The method of claim 1, further comprising setting half-tone image pixels corresponding to the portion of input pixels that are above the threshold based on the dithering.

### Claim 3 (depends on 1)

The method of claim 1, wherein dithering includes quantizing.

### Claim 4 (depends on 3)

The method of claim 3, wherein dithering further includes diffusing a quantization error.

### Claim 5 (depends on 4)

The method of claim 4, wherein the portion of input pixels below the crush threshold are quantized, and at least a portion of quantization error resulting from the quantizing is diffused to half-tone image pixels.

### Claim 6 (depends on 1)

The method of claim 1, wherein the output device is an electronic display.

### Claim 7 (depends on 1)

The method of claim 1, wherein the input image is received from an input device.

### Claim 8 (depends on 4)

The method of claim 4, further comprising clipping quantization error resulting from the quantizing before diffusing the quantization error.

### Claim 9 (depends on 1)

The method of claim 1, wherein the dithering utilizes Floyd Steinberg Error Diffusion.

### Claim 10 (depends on 1)

The method of claim 1, wherein the dithering adds noise to the input pixels.

### Claim 11 (depends on 1)

The method of claim 1, wherein the crush threshold is between four percent and six percent of a dynamic range of a plurality of input pixels.

### Claim 12 (depends on 1)

The method of claim 1, further comprising utilizing a second crush threshold for green pixels that is lower than the crush threshold, which is used for non-green pixels.

### Claim 13 (depends on 1)

An electronic display displaying an image comprised of a plurality of pixel values determined based on the method of claim 1.

### Claim 14

An apparatus for rendering at least a portion of a half-tone image on a display, comprising:
a processor;
a memory operably connected to the processor, the memory configured to store:
an image receiver module, configured to receive an input image including a plurality of input pixels,
a dithering module, configured to dither at least a portion of the input pixels,
a pixel crush module, configured to set half-tone image pixels corresponding to the portion of the input pixels that are below a crush threshold to a crushed value, and
an output module, configured to output the half-tone image pixels to an output device.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein the dithering module is further configured to set half-tone image pixels corresponding to the portion of input pixels that are above the threshold based on the dithering.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein the dithering module is further configured to quantize the portion of the input pixels.

### Claim 17 (depends on 16)

The apparatus of claim 16, wherein the dithering module is further configured to diffuse a quantization error resulting from the quantizing.

### Claim 18 (depends on 17)

The apparatus of claim 17, wherein the dithering module is further configured to diffuse at least a portion of the quantization error resulting from quantizing the portion of input pixels below the crush threshold to half-tone image pixels.

### Claim 19 (depends on 17)

The apparatus of claim 17, further comprising an error clipping module, configured to clip quantization error resulting from the quantizing before diffusing the quantization error.

### Claim 20 (depends on 14)

The apparatus of claim 14 wherein the dithering module is further configured to implement Floyd Steinberg Error Diffusion for at least a portion of the input pixels.

### Claim 21 (depends on 14)

The apparatus of claim 14, wherein the dithering module is further configured to add noise to a portion of the input pixels.

### Claim 22 (depends on 14)

The apparatus of claim 14, wherein the crush threshold is between four percent and six percent of a dynamic range of a plurality of input pixels.

### Claim 23 (depends on 14)

The apparatus of claim 14, wherein the pixel crush module is further configured to utilize a second crush threshold for green pixels that is lower than the crush threshold, wherein the crush threshold is used for non-green pixels.

### Claim 24

An apparatus for rendering at least a portion of a half-tone image on a display, comprising:
means for receiving an input image including a plurality of input pixels;
means for dithering at least a portion of the input pixels;
means for setting half-tone image pixels corresponding to the portion of the input pixels that are below a crush threshold to a crushed value; and
means for outputting the half-tone image pixels to an output device.

### Claim 25 (depends on 24)

The apparatus of claim 24, further comprising means for setting half-tone image pixels corresponding to the portion of input pixels that are above the threshold based on the dithering.

### Claim 26 (depends on 24)

The apparatus of claim 24, wherein the means for dithering is configured to quantize the portion of the input pixels.

### Claim 27 (depends on 26)

The apparatus of claim 26, wherein the means for dithering is further configured to diffuse a quantization error.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein the means for dithering is further configured to diffuse at least a portion of the quantization error resulting from quantizing the portion of input pixels below the crush threshold to half-tone image pixels.

### Claim 29 (depends on 27)

The apparatus of claim 27, further comprising means for clipping quantization error resulting from the quantizing before diffusing the quantization error.

### Claim 30 (depends on 24)

The apparatus of claim 24, wherein the means for dithering is further configured to utilize Floyd Steinberg Error Diffusion.

### Claim 31 (depends on 24)

The apparatus of claim 24, wherein the means for dithering is further configured to add noise to the input pixel.

### Claim 32 (depends on 24)

The apparatus of claim 24, wherein the crush threshold is between four percent and six percent of a dynamic range of a plurality of input pixels.

### Claim 33 (depends on 24)

The apparatus of claim 24, further comprising means for utilizing a second crush threshold for green pixels that is lower than the crush threshold, and wherein the crush threshold is used for non-green pixels.

### Claim 34

A non-transitory, computer readable medium comprising instructions that when executed causes one or more processors to perform a method of rendering at least a portion of a half-tone image on a display, the method comprising:
receiving an input image including a plurality of input pixels;
dithering at least a portion of the input pixels;
setting half-tone image pixels corresponding to the portion of the input pixels that are below a crush threshold to a crushed value; and
outputting the half-tone image pixels to an output device.

### Claim 35 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein the method further comprises setting half-tone image pixels corresponding to the portion of input pixels that are above the threshold based on the dithering.

### Claim 36 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein dithering includes quantizing the portion of the input pixels.

### Claim 37 (depends on 36)

The non-transitory, computer readable medium of claim 36, wherein dithering further includes diffusing a quantization error resulting from quantizing the input pixels.

### Claim 38 (depends on 37)

The non-transitory, computer readable medium of claim 37, wherein at least a portion of the quantization error resulting from quantizing the portion of input pixels below the crush threshold is diffused to half-tone image pixels.

### Claim 39 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein the dithering utilizes Floyd Steinberg Error Diffusion.

### Claim 40 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein the dithering adds noise to the input pixel.

### Claim 41 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein the crush threshold is between four percent and six percent of a dynamic range of a plurality of input pixels.

### Claim 42 (depends on 34)

The non-transitory, computer readable medium of claim 34, wherein the method further includes utilizing a second crush threshold for green pixels that is lower than the crush threshold, wherein the crush threshold is used for non-green pixels.