A computing system may access first alpha values associated with first pixels in a first pixel region of an image and determine a bit budget for encoding the first alpha values. The computing system may then select a first alpha-encoding mode for the first alpha values to reflect a determination that the first alpha values are all fully transparent or all fully opaque, and encode the first alpha values by storing the selected first alpha-encoding mode as part of a metadata without using the bit budget to encode the first alpha values individually. The computing system may then update a record of unallocated bits available for allocation based on the bit budget unused in the encoding of the first alpha values, and allocate, based on the record of unallocated bits, bits to encode a set of alpha values different from the first alpha values.

Image coding using alpha channel prediction may include generating a reconstructed image using alpha channel prediction and outputting the reconstructed image. Generating the reconstructed image using alpha channel prediction may include decoding reconstructed color channel values for a current pixel expressed with reference to first color space, obtaining color space converted color channel values for the current pixel by converting the reconstructed color channel values to a second color space, obtaining an alpha channel lower bound for an alpha channel value for the current pixel using the color space converted color channel values, generating a candidate predicted alpha value for the current pixel, obtaining an adjusted predicted alpha value for the current pixel using the candidate predicted alpha value and the alpha channel lower bound, generating a reconstructed pixel for the current pixel using the adjusted predicted alpha value, and including the reconstructed pixel in the reconstructed image.

A method of encoding a video data signal (15) is provided, together with a method for decoding. The encoding comprises providing color information (51) for pixels in an image, providing a depth map with depth information (52) for the pixels, providing transition information (56, 57, 60, 70, 71) being representative of a width (63, 73) of a transition region (61, 72) in the image, the transition region (61, 72) comprising a depth transition (62) and blended pixels in which colors of a foreground object and a background object are blended, and generating (24) the video data signal (15) comprising encoded data representing the color information (51), the depth map (52) and the transition information (56, 57, 60, 70, 71). The decoding comprises using the transition information (56, 57, 60, 70, 71) for determining the width (63, 73) of the transition regions (61, 72) and for determining alpha values (53) for pixels inside the transition regions (61, 72). The determined alpha values (53) are used for determining the color of a blended pixel at the transition of a foreground object and a background object.

A method of encoding a video data signal (15) is provided, together with a method for decoding. The encoding comprises providing color information (51) for pixels in an image, providing a depth map with depth information (52) for the pixels, providing transition information (56, 57, 60, 70, 71) being representative of a width (63, 73) of a transition region (61, 72) in the image, the transition region (61, 72) comprising a depth transition (62) and blended pixels in which colors of a foreground object and a background object are blended, and generating (24) the video data signal (15) comprising encoded data representing the color information (51), the depth map (52) and the transition information (56, 57, 60, 70, 71). The decoding comprises using the transition information (56, 57, 60, 70, 71) for determining the width (63, 73) of the transition regions (61, 72) and for determining alpha values (53) for pixels inside the transition regions (61, 72). The determined alpha values (53) are used for determining the color of a blended pixel at the transition of a foreground object and a background object.

The image decoding method includes determining a context for use in a current block to be processed, from among a plurality of contexts, wherein in the determining: the context is determined under a condition that control parameters of a left block and an upper block are used, when the signal type is a first type; and the context is determined under a third condition that the control parameter of the upper block is not used and a hierarchical depth of a data unit to which the control parameter of the current block belongs is used, when the signal type is a third type, and the third type is one or more of (i) “merge_flag”, (ii) “ref_idx_I0” or “ref_idx_I1”, (iii) “inter_pred_flag”, (iv) “mvd_I0” or “mvd_I1”, (v) “intra_chroma_pred_mode”, (vi) “cbf_luma”, and (vii) “cbf_cb” or “cbf_cr”.

The image decoding method includes determining a context for use in a current block to be processed, from among a plurality of contexts, wherein in the determining: the context is determined under a condition that control parameters of a left block and an upper block are used, when the signal type is a first type; and the context is determined under a third condition that the control parameter of the upper block is not used and a hierarchical depth of a data unit to which the control parameter of the current block belongs is used, when the signal type is a third type, and the third type is one or more of (i) “merge_flag”, (ii) “ref_idx_I0” or “ref_idx_I1”, (iii) “inter_pred_flag”, (iv) “mvd_I0” or “mvd_I1”, (v) “intra_chroma_pred_mode”, (vi) “cbf_luma”, and (vii) “cbf_cb” or “cbf_cr”.

To represent a 3D scene, the MPI format uses a set of fronto-parallel planes. Different from MPI, the current MIV standard accepts a 3D scene represented as sequence input pairs of texture and depth pictures as input. To enable transmission of an MPI cube via the MIV-V3C standard, in one embodiment, an MPI cube is divided into empty regions and local MPI partitions that contain 3D objects. Each partition in the MPI cube can be projected to one or more patches. For a patch, the geometry is generated as well as the texture attribute and alpha attributes, and the alpha attributes may be represented as a peak and a width of an impulse. In another embodiment, an MPI RGBA layer of the MPI is cut into sub-images. Each sub-image may correspond to a patch, and the RGB and alpha information of the sub-image are assigned to the patch.

A method, system and computer program product for segmenting generic foreground objects in images and videos. For segmenting generic foreground objects in videos, an appearance stream of an image in a video frame is processed using a first deep neural network. Furthermore, a motion stream of an optical flow image in the video frame is processed using a second deep neural network. The appearance and motion streams are then joined to combine complementary appearance and motion information to perform segmentation of generic objects in the video frame. Generic foreground objects are segmented in images by training a convolutional deep neural network to estimate a likelihood that a pixel in an image belongs to a foreground object. After receiving the image, the likelihood that the pixel in the image is part of the foreground object as opposed to background is then determined using the trained convolutional deep neural network.

In one embodiment, a computing system may access first alpha values associated with first pixels in a first pixel region of an image and determine a bit budget for encoding the first alpha values. The computing system may then select a first alpha-encoding mode for the first alpha values to reflect a determination that the first alpha values are all fully transparent or all fully opaque, and encode the first alpha values by storing the selected first alpha-encoding mode as part of a metadata without using the bit budget to encode the first alpha values individually. The computing system may then update a record of unallocated bits available for allocation based on the bit budget unused in the encoding of the first alpha values, and allocate, based on the record of unallocated bits, bits to encode a set of alpha values different from the first alpha values.

A probably update method used in context-based adaptive binary arithmetic coding (CABAC) is disclosed. The probably update method for binary arithmetic decoding obtains an autocorrelation value of each bin by using values of received bins, determines at least one scaling factor used to update a probability of a binary value based on the autocorrelation value, and updates a probability used in context-based adaptive binary arithmetic decoding by using the determined at least one scaling factor.