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US 10,432,937 B2Granted
Adaptive precision and quantification of a wavelet transformed matrix
AssigneeJean-Claude Colin
InventorsThan Marc-Eric Gervais, Bruno Loubet, Nicolas Bessou, Yves Guimiot, Mickael Petitfils, Sebastien Roques
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Abstract
A method for reducing the entropy of an original matrix, includes a step using a wavelet transformation of the original matrix into a transformed matrix, a quantization coefficient corresponding to each wavelet level, the wavelet transformation being calculated in fixed decimal point using a first number of digits at least equal to 1, for example 3 digits, after the decimal point. Such a method is particularly advantageous for image compression.
Claims26
A method for compressing a digital image, comprising:
- a step for reducing an entropy of a component of said image, represented in a form of an original matrix (X), wherein:
- said original matrix is transformed into a transformed matrix (T) using a wavelet transformation;
- a respective quantisation coefficient corresponds to each detail matrix for each of plural detail matrices;
- said wavelet transformation is calculated in fixed decimal point using a first number (D) of digits, wherein D≥1, after the decimal point, for each wavelet level for which at least one of the quantisation coefficients corresponding to each of the detail matrices is strictly greater than 1, and
- at the end of the processing of a wavelet level in fixed-decimal point numbers, values of an approximation matrix are transformed into integer numbers when each of the quantisation coefficients of each of the detail matrices of a subsequent wavelet level is equal to 1, and are kept in fixed-decimal point numbers in the contrary case.
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