ImageMagick
#!/bin/sh
for FullFileName in *.png;
do
FileName=`echo "$FullFileName" | awk 'BEGIN {FS="."} {for (i=1;i<NF;i++) {printf($i); if (i < NF-1) {printf(".")}}} END {printf("\n")}'`;
convert "$FullFileName" \
-filter Gaussian \
+repage \
-resize 700x700 \
\( +clone -alpha extract -draw 'fill black polygon 0,0 0,15 15,0 fill white circle 15,15 15,0' \
\( +clone -flip \) -compose Multiply -composite \
\( +clone -flop \) -compose Multiply -composite \) \
-alpha off -compose CopyOpacity -composite\
-unsharp 0x1 \
"../$FileName.png";
done