Apparatus and method for encoding a picture regarding a region of interest
View Patent ↗An apparatus for encoding a sample array which signals a spatially sampled representation of a picture, wherein the apparatus is configured for: spectrally decomposing the sample array to obtain a decomposed representation, the decomposed representation comprising a plurality of coefficients, each of which is attributed to one of a plurality of spectral components of the decomposed representation and to one of a plurality of spatial components of the sample array; obtaining, from the plurality of coefficients, a subset of coefficients which are, according to the spatial components to which the coefficients are attributed, located outside of a predetermined region spatially defined within the sample array; attenuating the coefficients of the subset of coefficients, wherein an extent of an attenuation of a coefficient of the subset of coefficients depends on the spatial component to which the coefficient is attributed.
1 . Apparatus for encoding a sample array which signals a spatially sampled representation of a picture, wherein the apparatus is configured for
spectrally decomposing the sample array to obtain a decomposed representation, the decomposed representation comprising a plurality of coefficients, each of which is attributed to one of a plurality of spectral components of the decomposed representation and to one of a plurality of spatial components of the sample array,
obtaining, from the plurality of coefficients, a subset of coefficients which are, according to the spatial components to which the coefficients are attributed, located outside of a predetermined region spatially defined within the sample array,
attenuating the coefficients of the subset of coefficients, wherein an extent of an attenuation of a coefficient of the subset of coefficients depends on the spatial component to which the coefficient is attributed, wherein the apparatus is configured for, in attenuating the coefficients, leaving coefficients attributed to a zero-frequency component unaffected.
2 . Apparatus according to claim 1 , configured for obtaining the subset of coefficients so that the coefficients of the subset of coefficients are attributed to a predetermined spectral component of the plurality of spectral components.
3 . Apparatus according to claim 1 , wherein the predetermined spectral component represents a frequency that is higher than a frequency represented by a further spectral component of the plurality of spectral components.
4 . Apparatus according to claim 1 , wherein the extent of the attenuation of the coefficient depends on a distance between the spatial component, to which the coefficient is attributed, and the predetermined portion.
5 . Apparatus according to claim 1 , wherein, in attenuating the coefficients of the subset of coefficients, an attenuation of a first coefficient of the subset, which is attributed to a spatial component having a larger distance to the predetermined portion than a spatial component associated to a second coefficient of the subset, is larger than an attenuation of the second coefficient.
6 . Apparatus according to claim 1 , configured for, in attenuating the coefficients, setting a coefficient attributed to a spatial component, the distance of which to the predetermined region exceeds a predetermined threshold, to a predetermined value.
7 . Apparatus according to claim 1 , configured for attenuating the coefficients of the subset by multiplying each of the coefficients of the subset with a factor which depends on the distance between the spatial component, to which the coefficient is attributed, and the predetermined portion.
8 . Apparatus according to claim 1 , further configured for quantizing the plurality of coefficients to obtain quantized coefficients, and
entropy encoding the quantized coefficients.
9 . Apparatus according to claim 8 , configured for spatially varying a quantization parameter.
10 . Apparatus according to claim 1 , configured for spectrally decomposing the sample array using a discrete wavelet transformation, DWT to obtain the decomposed representation.
11 . Apparatus according to claim 1 , configured for spectrally decomposing the sample array by subjecting the sample array to a discrete sine transformation, DST, or a discrete cosine transformation, DCT, in units of portions into which the sample array is subdivided to obtain the decomposed representation.
12 . Apparatus according to claim 1 , configured for filtering samples of the sample array, which samples are located outside of the predetermined region, using a blurring filter prior to spectrally decomposing the sample array.
13 . Apparatus according to claim 12 , wherein a blurring intensity of the blurring filter varies in dependence on a spatial distance between samples to be filtered and the predetermined portion.
14 . Apparatus according to claim 12 , wherein the blurring filter is a Gaussian filter, wherein a spatial width of the Gaussian filter depends on a spatial distance between samples to be filtered and the predetermined portion.
15 . Apparatus according to claim 1 , configured for obtaining an indication of the predetermined region.
16 . Apparatus according to claim 1 , wherein the predetermined region is determined by a user device by eye-tracking.
17 . Apparatus according to claim 1 , configured for encoding the sample array into a data stream to be decoded by a virtual reality device.
18 . Method for encoding a sample array which signals a spatially sampled representation of a picture, wherein the method comprises
spectrally decomposing the sample array to obtain a decomposed representation, the decomposed representation comprising a plurality of coefficients, each of which is attributed to one of a plurality of spectral components of the decomposed representation and to one of a plurality of spatial components of the sample array,
obtaining, from the plurality of coefficients, a subset of coefficients which are, according to the spatial components to which the coefficients are attributed, located outside of a predetermined region spatially defined within the sample array,
attenuating the coefficients of the subset of coefficients, wherein an extent of an attenuation of a coefficient of the subset of coefficients depends on the spatial component to which the coefficient is attributed, wherein, in attenuating the coefficients, coefficients attributed to a zero-frequency component unaffected are left unaffected.
19 . Method according to claim 18 , further comprising:
filtering samples of the sample array, which samples are located outside of the predetermined region, using a blurring filter prior to spectrally decomposing the sample array.
20 . Method according to claim 19 , wherein a blurring intensity of the blurring filter depends on a distance between samples to be filtered and the predetermined portion.
21 . A non-transitory computer readable storage medium having stored a computer program for causing a computer to perform the method according to claim 19 .
22 . Apparatus for encoding a sample array which signals a spatially sampled representation of a picture, wherein the apparatus is configured for
spectrally decomposing the sample array to obtain a decomposed representation, the decomposed representation comprising a plurality of coefficients, each of which is attributed to one of a plurality of spectral components of the decomposed representation and to one of a plurality of spatial components of the sample array,
obtaining, from the plurality of coefficients, a subset of coefficients which are, according to the spatial components to which the coefficients are attributed, located outside of a predetermined region spatially defined within the sample array,
attenuating the coefficients of the subset of coefficients, wherein an extent of an attenuation of a coefficient of the subset of coefficients depends on the spatial component to which the coefficient is attributed,
wherein the apparatus is configured for attenuating the coefficients of the subset by multiplying each of the coefficients of the subset with a factor which depends on the distance between the spatial component, to which the coefficient is attributed, and the predetermined portion.
23 . Method for encoding a sample array which signals a spatially sampled representation of a picture, wherein the method comprises
spectrally decomposing the sample array to obtain a decomposed representation, the decomposed representation comprising a plurality of coefficients, each of which is attributed to one of a plurality of spectral components of the decomposed representation and to one of a plurality of spatial components of the sample array,
obtaining, from the plurality of coefficients, a subset of coefficients which are, according to the spatial components to which the coefficients are attributed, located outside of a predetermined region spatially defined within the sample array,
attenuating the coefficients of the subset of coefficients, wherein an extent of an attenuation of a coefficient of the subset of coefficients depends on the spatial component to which the coefficient is attributed, wherein the method comprises attenuating the coefficients of the subset by multiplying each of the coefficients of the subset with a factor which depends on the distance between the spatial component, to which the coefficient is attributed, and the predetermined portion.
24 . A non-transitory computer readable storage medium having stored a computer program for causing a computer to perform the method according to claim 23 .