	US 7,548,656 B2
	Method and apparatus for processing image signals by applying a multi-resolution conversion processing for reducing the image size and applying a dyadic wavelet transform
Takeshi Nakajima, Hino (Japan); Tsukasa Ito, Musashino (Japan); Tsuyoshi Hattori, Hidaka (Japan); Shoichi Nomura, Hachioji (Japan); and Chizuko Ikeda, Tokyo (Japan)
Assigned to Konica Minolta Holdings, Inc., Tokyo (Japan)
Filed on Jan. 08, 2004, as Appl. No. 10/754,003.
Claims priority of application No. 2003-008217 (JP), filed on Jan. 16, 2003.
Prior Publication US 2004/0234166 A1, Nov. 25, 2004
Int. Cl. G06K 9/36 (2006.01); G06K 9/46 (2006.01)

U.S. Cl. 382—240

32 Claims

1. A method for processing image signals, comprising:

reading an image recorded on a recording medium so as to generate image signals representing said image;

applying, to said image signals, using a processing unit, a multi-resolution conversion processing of at least level 1, which is capable of reducing an image size of said image signals, so as to generate first-converted image signals from said image signals; and

applying a Dyadic Wavelet transform of at least level 1 to lowest frequency band component signals included in said first-converted image signals, so as to generate second-converted image signals from said first-converted image signals;

wherein no down-sampling is performed in said Dyadic Wavelet transform, and wavelet function ψ_i,j(x) to be employed in said Dyadic Wavelet transform is defined by an equation shown below:

where “i” and “j” denote natural numbers;

wherein an image size of said first-converted image signals is smaller than the image size of said image signals, while an image size of said second-converted image signals is identical to the image size of said first-converted image signals;

wherein the method further comprises determining a changeover level from said multi-resolution conversion processing to said Dyadic Wavelet transform, based on a resolution of said read image signals; and

wherein said multi-resolution conversion processing is applied to said image signals according to said determined changeover level, and said Dyadic Wavelet transform is applied to said low frequency band component signals according to said determined changeover level.