Image encoding based on alpha channel
AssigneeVarjo Technologies Oy
InventorsAri Antti Erik Peuhkurinen, Timo Suoranta
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Abstract
Disclosed is an encoder for encoding images, the encoder having a processor configured to obtain colour data of colour channels of a given image and alpha data of an alpha channel of the given image; identify at least one portion of the given image whose alpha values are zero or less than a predefined threshold value, wherein a zero alpha value indicates full transparency; divide a remaining portion of the given image into blocks, wherein the colour data and the alpha data of the remaining portion are divided into their own respective blocks; and encode the blocks into encoded data.
Claims19
An encoder for encoding images, the encoder comprising a processor configured to:
- obtain colour data of colour channels of a given image and alpha data of an alpha channel of the given image;
- identify at least one portion of the given image whose alpha values are zero or less than a predefined threshold value, wherein a zero alpha value indicates full transparency;
- divide a remaining portion of the given image into blocks, wherein the colour data and the alpha data of the remaining portion are divided into their own respective blocks;
- and
- encode the blocks into encoded data;
- wherein the given image is divided into the blocks in a hierarchical manner, based on at least one of:
- a dynamic range of at least one of:
- the colour values, the alpha values in the blocks,
- a manner in which at least one of:
- colour values, alpha values change in the blocks,
- wherein when dividing, the processor is configured to:
- initially divide the colour data and the alpha data into respective blocks at a same level of division depth;
- and
- further divide at least one block of the alpha data into smaller blocks, based on a dynamic range of alpha values in the at least one block of the alpha data.
A method of encoding images, the method comprising:
- obtaining colour data of colour channels of a given image and alpha data of an alpha channel of the given image;
- identifying at least one portion of the given image whose alpha values are zero or less than a predefined threshold value, wherein a zero alpha value indicates full transparency;
- dividing a remaining portion of the given image into blocks, wherein the colour data and the alpha data of the remaining portion are divided into their own respective blocks;
- and
- encoding the blocks into encoded data;
- wherein the given image is divided into the blocks in a hierarchical manner, based on at least one of:
- a dynamic range of at least one of:
- the colour values, the alpha values in the blocks,
- a manner in which at least one of:
- colour values, alpha values change in the blocks;
- wherein the step dividing comprises:
- initially dividing the colour data and the alpha data into respective blocks at a same level of division depth;
- and
- further dividing at least one block of the alpha data into smaller blocks, based on a dynamic range of alpha values in the at least one block of the alpha data.
Dependencies are inferred from the claim text.