Patent ID: 8537891

Claim:
A method for compressing a digital image, comprising: receiving selected quality numbers from a user; mapping the selected quality numbers to sets of quantizers of wavelet sub-bands; and generating a luminance preview of the digital image for the selected quality numbers by: applying a discrete wavelet transform to a luminance channel of the digital image; quantizing discrete wavelet transform coefficients based on the selected quality numbers; storing the discrete wavelet transform coefficients; and generating rate-distortion information during entropy encoding the transformed digital image using the mapped quantizers, the mapped quantizers chosen to minimize loss of image quality; storing the rate-distortion information from the generating rate distortion information during the entropy encoding; creating a preview buffer for the luminance preview of the digital image using the stored discrete wavelet transform coefficients; performing rate-distortion optimization on the encoded luminance preview of the digital image in the preview buffer, the performing creating one or more bitplanes; discarding unneeded bitplanes created during the performing rate-distortion optimization; dequantizing the luminance preview of the digital image using the stored discrete wavelet transform coefficients; transforming the luminance preview of the digital image with an inverse wavelet transformation; and displaying the luminance preview of the digital image.