# US 12,761,603 B2 · Method and apparatus for compressing hologram

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

- Number: US 12,761,603 B2
- Document ID: US12761603B2
- Status: Granted
- Kind: B2
- Application number: 18/638,918
- Filed: 2024-04-18
- Published: 2024-10-24
- Granted: 2026-10-13
- Earliest claimed: 2023-04-18
- Assignees: Electronics and Telecommunications Research Institute
- Applicants: Electronics and Telecommunications Research Institute
- Inventors: Min Sik Park; Joong Ki Park
- Web page: https://patentgrep.com/patent/US12761603B2

## CPC

- G03H 1/16: using Fourier transform ({G03H1/10}, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19)
- G03H 1/0808: {Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific}
- H04N 19/61: in combination with predictive coding
- H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards
- G03H 2225/32: Phase only
- G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00})
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A method and apparatus for compressing hologram is disclosed. The apparatus includes memory to store one or more instructions, and one or more processors to execute the one or more instructions in the memory, wherein the one or more processors perform generating phase wavefront blocks using a frame of a phase-only hologram, generating a first prediction wavefront block using one of the phase wavefront blocks, generating a differential wavefront block using a phase wavefront block and the first prediction wavefront block, transforming and quantizing the differential wavefront block, generating a restored differential wavefront block by inversely quantizing and inversely transforming the differential wavefront block transformed and quantized, generating a restored phase wavefront block using the restored differential wavefront block, generating a restored phase wavefront using restored phase wavefront blocks generated using the restored differential wavefront blocks, and restoring the phase-only hologram using the restored phase wavefront.

## Claims

### Claim 1

An apparatus for compressing a hologram, the apparatus comprising:
a memory configured to store one or more instructions; and
one or more processors configured to execute the one or more instructions stored in the memory,
wherein the one or more processors, by executing the one or more instructions, perform steps comprising:
generating a plurality of phase wavefront blocks by using a certain frame of a phase-only hologram;
generating a Zernike coefficient block from a phase wavefront block among the plurality of phase wavefront blocks;
generating a first prediction wavefront block by using the phase wavefront block and the Zernike coefficient block;
generating a differential wavefront block by using the phase wavefront block and the first prediction wavefront block;
transforming and quantizing the differential wavefront block;
generating a restored differential wavefront block by inversely quantizing and inversely transforming the differential wavefront block which is transformed and quantized;
generating a restored phase wavefront block by using the restored differential wavefront block;
generating a restored phase wavefront by using a plurality of restored phase wavefront blocks which are generated by using the restored differential wavefront blocks; and
restoring the phase-only hologram by using the restored phase wavefront.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the one or more processors further perform a step of:
generating a motion vector and a second prediction wavefront block by predicting a motion of a phase wavefront block from a plurality of restored phase wavefronts which are generated by using the restored differential wavefront block.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the generating the differential wavefront block includes:
generating the differential wavefront block by using the difference between the phase wavefront block and one selected from between the first prediction wavefront block and the second prediction wavefront block.

### Claim 4 (depends on 2)

The apparatus of claim 2, wherein the generating a restored phase wavefront block includes:
generating the restored phase wavefront block by combining the restored differential wavefront block with one selected from between the first prediction wavefront block and the second prediction wavefront block.

### Claim 5 (depends on 2)

The apparatus of claim 2, wherein the one or more processors further perform a step of:
losslessly compressing the differential wavefront block which is transformed and quantized, the Zernike coefficient block, and the motion vector.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the transforming and quantizing the differential wavefront block includes:
transforming the differential wavefront block by using the discrete cosine transform (DCT).

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the generating the plurality of phase wavefront blocks includes:
generating the plurality of phase wavefront blocks from the phase-only hologram by using a phase unwrapping technique.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein the generating the restored phase wavefront includes:
generating the restored phase wavefront by combining the plurality of restored phase wavefront blocks and removing fringes therebetween.

### Claim 9 (depends on 1)

The apparatus of claim 1, wherein the restoring the phase-only hologram includes:
restoring the phase-only hologram by using a phase wrapping technique in which the phase period is 2.

### Claim 10

A method for compressing and restoring a hologram, the method comprising:
generating a plurality of phase wavefront blocks by using a certain frame of a phase-only hologram;
generating a Zernike coefficient block from a phase wavefront block among the plurality of phase wavefront blocks;
generating a first prediction wavefront block by using the phase wavefront block and the Zernike coefficient block;
generating a differential wavefront block by using the phase wavefront block and the first prediction wavefront block;
transforming and quantizing the differential wavefront block;
generating a restored differential wavefront block by inversely quantizing and inversely transforming the differential wavefront block which is transformed and quantized;
generating a restored phase wavefront block by using the restored differential wavefront block;
generating a restored phase wavefront by combining a plurality of restored phase wavefront blocks which are generated by using the restored differential wavefront blocks; and
restoring the phase-only hologram from the restored phase wavefront.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
generating a motion vector and a second prediction wavefront block by predicting a motion of a phase wavefront block from a plurality of restored phase wavefronts which are generated by using the restored differential wavefront block.

### Claim 12 (depends on 11)

The method of claim 11, wherein the generating the differential wavefront block includes:
generating the differential wavefront block by using the difference between the phase wavefront block and one selected from between the first prediction wavefront block and the second prediction wavefront block.

### Claim 13 (depends on 11)

The method of claim 11, wherein the generating the restored phase wavefront block includes:
generating the restored phase wavefront block by combining the restored differential wavefront block with one selected from between the first prediction wavefront block and the second prediction wavefront block.

### Claim 14 (depends on 11)

The method of claim 11, further comprising:
losslessly compressing the differential wavefront block which is transformed and quantized, the Zernike coefficient block, and the motion vector.

### Claim 15 (depends on 10)

The method of claim 10, wherein the transforming and quantizing the differential wavefront block includes:
transforming the differential wavefront block by using the discrete cosine transform (DCT).

### Claim 16 (depends on 10)

The method of claim 10, wherein the generating the restored phase wavefront includes:
generating the restored phase wavefront by combining the plurality of restored phase wavefront blocks and removing fringes therebetween.

### Claim 17 (depends on 10)

The method of claim 10, wherein the generating the plurality of phase wavefront blocks includes:
transforming the phase-only program into the plurality of phase wavefront blocks by using a phase wrapping technique.

### Claim 18 (depends on 10)

The method of claim 10, wherein the restoring the phase-only hologram includes:
restoring the phase-only hologram by using a phase wrapping technique in which the phase period is 2π.