Alpha regions

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• storing the combined alpha image data structures in a third alpha image data structure;
• and
• rendering the third alpha image data structure onto a drawing surface;
• wherein combining two alpha image data structures flrther comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an OR combination operation on the alpha values of the respective pixels, wherein the OR operation selects the alpha value having the largest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• storing the combined alpha image data structures in a third alpha image data structure;
• and
• rendering the third alpha image data structure onto a drawing surface;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an AND combination operation on the alpha values of the respective pixels, wherein the AND operation selects the alpha value having the smallest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• storing the combined alpha image data structures in a third alpha image data structure;
• and
• rendering the third alpha image data structure onto a drawing surface;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an XOR combination operation on the alpha values of the respective pixels, wherein the XOR operation subtracts the alpha value having the smallest value from the alpha value having the largest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• storing the combined alpha image data structures in a third alpha image data structure;
• and
• rendering the third alpha image data structure onto a drawing surface;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing a SUBTRACT combination operation on the alpha values of the respective pixels, wherein the SUBTRACT operation subtracts the alpha value having the smallest value from the alpha value of the first alpha image data structure.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• storing the combined alpha image data structures in a third alpha image data structure;
• and
• rendering the third alpha image data structure onto a drawing surface;
• wherein combining two alpha image data structures further comprises compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing a SUBTRACT_FROM combination operation on the alpha values of the respective pixels, wherein the SUBTRACT_FROM operation subtracts the alpha value having the smallest value from the alpha value of the second alpha image data structure.

A method comprising:

• creating a first alpha image data structure from an image data source, wherein the image data source indicates at least one pixel having a default opacity value, and the first alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of an image, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of pixels of the semi-transparent span;
• and
• combining the first alpha image data structure with a second alpha image data structure, wherein pixels having the default opacity value are represented in the first alpha image data structure without storing an alpha value therefor, and pixels having the default opacity value are represented in the second alpha image data structure without storing an alpha value therefor.

A method of combining a first alpha image data structure having a plurality of semi-transparent alpha values with a second alpha image data structure having a plurality of semi-transparent alpha values, the method comprising:

• combining the first alpha image data structure with a second alpha image data structure;
• wherein the first alpha image data structure represents an image data source indicating at least one pixel having non-semi-transparent opacity;
• wherein the second alpha image data structure represents an image data source indicating at least one pixel having non-semi-transparent opacity;
• and
• wherein one or more pixels having non-semi-transparent opacity are represented in the first alpha image data structure without storing an alpha value therefor, and one or more pixels having non-semi-transparency opacity are represented in the second alpha image data structure without storing an alpha value therefor.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein creating an alpha image data structure from an image data source further comprises:
• recording the number of adjacent spans having an identical pattern of alpha values that comprise the arbitrary 2-dimensional shape in the alpha image data structure;
• classifying each span or portion of a span as semi-transparent or opaque, and storing the starting location and extent of each span or portion of a span in the alpha image data structure, wherein the extent is stored as a positive number if the span or portion of a span is opaque, and is stored as a negative number if the span or portion of a span is semi-transparent;
• recording the alpha values associated with the semi-transparent spans or portions of spans, in the alpha image data structure, wherein only the first occurrence of an identical pattern of alpha values occurring within the arbitrary 2-dimensional shape is recorded;
• recording the location of the semi-transparent or opaque spans and portions of spans in a first offset of the alpha image data structure;
• recording the location of the alpha data for the adjacent span having an identical pattern of alpha values in a second offset of the alpha image data structure.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an OR combination operation on the alpha values of the respective pixels, wherein the OR operation selects the alpha value having the largest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an AND combination operation on the alpha values of the respective pixels, wherein the AND operation selects the alpha value having the smallest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing an XOR combination operation on the alpha values of the respective pixels, wherein the XOR operation subtracts the alpha value having the smallest value from the alpha value having the largest value.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein combining two alpha image data structures further comprises:
• compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing a SUBTRACT combination operation on the alpha values of the respective pixels, wherein the SUBTRACT operation subtracts the alpha value having the smallest value from the alpha value of the first alpha image data structure.

A method for storing and processing arbitrary 2-dimensional shapes in a graphics system, comprising:

• creating an alpha image data structure from an image data source, wherein the alpha image data structure comprises the following elements:
• data representing the starting location and extent of a span of pixels of a scanned image of a shape, wherein the span of pixels is semi-transparent;
• and
• data representing the alpha values quantifying the opacity of each pixel of the semi-transparent span;
• combining the alpha image data structure with a second alpha image data structure, wherein the second alpha image data structure represents a second image data source;
• and
• storing the combined alpha image data structures in a third alpha image data structure;
• wherein combining two alpha image data structures further comprises compositing the alpha values of the pixel defined by the first alpha image data structure with the corresponding pixel from the second alpha image data structure and performing a SUBTRACT_FROM combination operation on the alpha values of the respective pixels, wherein the SUBTRACT_FROM operation subtracts the alpha value having the smallest value from the alpha value of the second alpha image data structure.