# US 5,708,729 A · Method and system for the reduction of memory capacity required for digital representation of an image

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- Number: US 5,708,729 A
- Document ID: US5708729A
- Status: Granted
- Kind: A
- Application number: 08/420,462
- Filed: 1995-04-12
- Granted: 1998-01-13
- Earliest claimed: 1995-04-12
- Assignees: Eastman Kodak Company
- Inventors: James E. Adams; Kevin E. Spaulding; Kenneth A. Parulski
- Web page: https://patentgrep.com/patent/US5708729A

## CPC

- G06T 9/00: Image coding (bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00)
- G06T 9/001: {Model-based coding, e.g. wire frame}
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A method for compressing a first bit digital input representative of first pixel data into a second bit digital output representative of second pixel data, the method comprises the steps of defining a logarithmic function for converting the first bit digital input into the second bit digital output; replacing a portion of the logarithmic function with a polynomial function; and compressing the first bit digital input into the second bit digital output by utilizing the logarithmic and polynomial function.

## Claims

### Claim 1

A method for compressing a first predetermined bit digital input representative of an image into a second predetermined bit digital output representative of the image, the method comprising the steps of:
(a) defining a logarithmic function for converting the first predetermined bit digital input into the second predetermined bit digital output;
(b) replacing a portion of the logarithmic function with a polynomial function for forming a resulting function which is continuous in value and slope; and
(c) compressing the first predetermined bit digital input into the second predetermined bit digital output, via a processor, by utilizing the logarithmic and polynomial function which compressing reduces the required storage capacity for storing the image, wherein the logarithmic and polynomial functions are substantially equal to: ##EQU19##

### Claim 2 (depends on 1)

The method as in claim 1, wherein step (b) includes:
(b1) calculating which portion of the logarithmic function includes a slope with a predetermined quantity; and
(b2) replacing the portion of the logarithmic function with a slope substantially at the predetermined quantity with the polynomial function which is continuous with the remaining portion of the logarithmic function.

### Claim 3 (depends on 2)

The method as in claim 2, wherein step (b1) includes calculating which portion of the logarithmic function includes a slope of a value of substantially one.

### Claim 4 (depends on 2)

The method as in claim 2, wherein step (b) includes calculating a polynomial which contains no discontinuity between it and the logarithmic function.

### Claim 5 (depends on 1)

The method as in claim 1 further comprising the step of: limiting the number of first bit digital input compressed into the second bit digital output substantially equal to: ##EQU20##

### Claim 6 (depends on 1)

The method as in claim 1 further comprising the step of converting the second predetermined bit digital output into the first bit digital input substantially equal to: ##EQU21##

### Claim 7 (depends on 1)

The method as in claim 1, wherein the logarithmic and polynomial functions are alternatively substantially equal to: ##EQU22##

### Claim 8 (depends on 1)

The method as in claim 1, wherein the logarithmic and polynomial functions are alternatively substantially equal to: ##EQU23##