invert-box-x-y

Arguments: stream left top right bottom

Inverts the pixels on stream that lie in a rectangular area from an upper-left corner at (left, top) to a lower-right corner at (right, bottom). stream should be a graphical-stream. The other arguments should be integers. To use a box object rather than individual coordinates, see invert-box.

A pixel is inverted by reversing each bit in its value. If the stream is using true color, then inverting red produces cyan, for example, by turning off all of the red bits and turning on all of the green and blue bits. If the stream is using a palette instead, then the inverted color would be whatever color is found in the palette at the index that is produced by reversing the bits of the pixel's current palette index.

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Created 2015.5.21.