+
MARGIN_X=30
MARGIN_Y=206
SIZE_X=426
SEQ=3
-all: images/matita.xcf
+all:
+
+images: images/matita.xcf
for Y in `seq 0 $(SEQ)`; do \
convert images/matita.png -crop \
$(SIZE_X)x$(SIZE_Y)+$(MARGIN_X)+`expr $(MARGIN_Y) + $$Y '*' '(' $(SIZE_Y) + 1 ')'` tmp.png; \