# US 7,609,764 B2 · Coding apparatus, coding method, program and information recording medium that can suppress unnatural degradation of image quality

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- Number: US 7,609,764 B2
- Document ID: US7609764B2
- Status: Granted
- Kind: B2
- Application number: 10/934,880
- Filed: 2004-09-03
- Published: 2005-05-26
- Granted: 2009-10-27
- Earliest claimed: 2003-09-05
- Assignees: Ricoh Company, Ltd.
- Inventors: Hiroyuki Sakuyama
- Web page: https://patentgrep.com/patent/US7609764B2

## CPC

- H04N 19/112: according to a given display mode, e.g. for interlaced or progressive display mode
- H04N 19/134: characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N 19/15: by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
- H04N 19/16: for a given display mode, e.g. for interlaced or progressive display mode
- H04N 19/63: using sub-band based transform, e.g. wavelets
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A coding apparatus includes a coding process unit that performs one of a field-based coding process and a frame-based coding process with respect to an interlaced image. A selection unit determines, based on a degree of quantization, which of the field-based coding process and the frame-based coding process is to be performed in the coding process unit.

## Claims

### Claim 1

A coding apparatus comprising:
a coding process unit to perform one of a field-based coding process and a frame-based coding process with respect to an interlaced image; and
a selection unit to determine which of the field-based coding process and the frame-based coding process is to be performed based on a magnitude relationship between a scaling factor designated by a user and a predetermined value;
wherein said frame-based coding process is to perform a 9×7 wavelet transform on each frame image, perform a quantization process using a quantization step number calculated based on the scaling factor designated by the user and a basic quantization step number with respect to each subband of each component, and perform an entropy coding on all bit planes of coefficients after quantization;
said field-based coding process is to perform the 9×7 wavelet transform on each field image, perform a quantization process using a quantization step number calculated based on the scaling factor designated by the user and a basic quantization step number with respect to each subband of each component, and perform an entropy coding on all bit planes of coefficients after quantization; and
wherein said selection unit is to compare a quantization step number at a high decomposition level with a threshold value so as to select the field-based coding process when the quantization step number exceeds the threshold value and select the frame-based coding process when the quantization step number does not exceed the threshold value.

### Claim 2 (depends on 1)

The coding apparatus as claimed in claim 1, wherein the basic quantization step number is acquired from a predetermined constant and a number determined by normalization for maximizing a peak signal to noise ratio (PSNR) under usage of a nonreversible component transform.