PHOTOS_ORIG = $(wildcard *.orig.jpg)
PHOTOS_MIN = $(patsubst %.orig.jpg,%.min.jpg,$(PHOTOS_ORIG))

MIN_WIDTH = 800
CONVERT_OPTIONS = -quality 75 -strip -interlace Plane

all: $(PHOTOS_MIN)

%.min.jpg: %.orig.jpg
	convert "$<" -size '$(MIN_WIDTH)x' $(CONVERT_OPTIONS) "$@"

clean:
	rm -f *.min.jpg