User Guide

458 ActionScript classes

A matrix convolution is based on an n x m matrix, which describes how a given pixel value in

the input image is combined with its neighboring pixel values to produce a resulting pixel

value. Each result pixel is determined by applying the matrix to the corresponding source pixel

and its neighboring pixels.

For a 3 x 3 matrix convolution, the following formula is used for each independent color

channel:

dst (x, y) = ((src (x-1, y-1) * a0 + src(x, y-1) * a1....

src(x, y+1) * a7 + src (x+1,y+1) * a8) / divisor) + bias

When run by a processor that offers SSE (Streaming SIMD Extensions), certain filter

specifications perform faster.

■ The filter must be a 3 x 3 filter.

■ All the filter terms must be integers between -127 and +127.

■ The sum of all the filter terms must not have an absolute value greater than 127.

■ If any filter term is negative, the divisor must be between 2.00001 and 256.

■ If all filter terms are positive, the divisor must be between 1.1 and 256.

■ The bias must be an integer.

A filter is not applied if the resulting image would exceed 2880 pixels in width or height. For

example, if you zoom in on a large movie clip with a filter applied, the filter is turned off if the

resulting image reaches the 2880-pixel limit.

Availability: ActionScript 1.0; Flash Player 8