Magnitude image compression
View Patent ↗Embodiments of the invention view image intensity data as a spectrum of underlying wave forms. The spectrum of these waves can be approximated using spectral estimation techniques where the spectrum parameters constitute the compressed image. The image's underlying wave forms can be recovered using an inverse Fourier transform. The original image can also be symmetrically extended prior to the transform to preserve real valued transformed data and model parameters. The modeling method is typically based on a linear predictive methodology to obtain the spectrum parameters. Other transforms include a 2-D Fourier transform that transforms the image into a holographic representation similar to synthetic aperture radar (SAR) phase history. This 2-D waveform holographic format can be decorrelated into 1-D planar waves by applying a 1D Fourier transform. This process enables 1-D linear predictive modeling to obtain the spectral parameters. For compression applications the model parameters are preferably quantized.
1. A computer implemented method of image processing, the method comprising:
transforming, by the computer, pixel intensity data of an image into a wave data description of the image by applying a two-dimensional Fourier transform to the pixel intensity data;
selecting, by the computer, a subset of the wave data description;
decorrelating, by the computer, the subset of the wave data description by applying a one-dimensional Fourier transform thereto;
modeling, by the computer, the decorrelated subset of the wave data description to obtain autoregressive (AR) model parameters thereof, wherein the AR model parameters constitute a compressed representation of the image;
computing, by the computer or a different computer, a synthesized spectrum representation directly from the AR model parameters without the intervening step of computing a Fourier transform of the AR model parameters, wherein the synthesized spectrum representation corresponds to a set of pixel intensity data of the image; and
reconstituting the image by computing a Fourier transform of the synthesized spectrum representation.
2. A non-transitory computer-readable medium for image processing comprising:
a transform module that transforms pixel intensity data of an image into a wave data description of the image by applying a two-dimensional Fourier transform to the pixel intensity data;
a modeling module that:
selects a subset of the wave data description;
decorrelates the subset of the wave data description by applying a one-dimensional Fourier transform thereto; and
models the decorrelated subset of the wave data description to obtain autoregressive (AR) model parameters thereof, wherein the AR model parameters constitute a compressed representation of the image;
a synthesis module that synthesizes a spectrum representation directly from the AR model parameters without the intervening step of computing a Fourier transform of the AR model parameters, wherein the synthesized spectrum representation corresponds to a set of pixel intensity data of the image; and
a reconstituting module that reconstitutes the image by computing a Fourier transform of the synthesized spectrum representation.