Something changed between versions 6.9.0-9 and 6.9.3-4 of ImageMagick that causes the imagick borderImage function to act differently. In the older versions you could round the corners on an image and then add a border that followed the contour of the round corners. When creating the same border with the new version, the inside of the border (closest to the picture) is always squared off, ignoring the rounded corners. This leaves a small, transparent triangle shape at the four corners between the inside of the new border and the rounded edges of the image.
I realize there are other solutions to get the desired effect. I'm just wondering why it changed.
Thanks