(PECL imagick 2.0.0)
Rounds image corners
bool Imagick::roundCorners ( float $x_rounding, float $y_rounding [, float $stroke_width = 10 [, float $displace = 5 [, float $size_correction = -6 ]]] )
Rounds image corners. The first two parameters control the amount of rounding and the three last parameters can be used to fine-tune the rounding process. This method is available if Imagick has been compiled against ImageMagick