IMAGES = $(wildcard jpgs/*)
COL = $(patsubst jpgs/%,collection/%,$(IMAGES))

.PHONY: help
help:
	$(info try 'show' or 'output')
.PHONY: show
show:
	$(info IMAGES is $(IMAGES))
	$(info Col is $(COL))

.PHONY: output
output: $(COL)

collection/%.jpg: jpgs/%.jpg
	mkdir -p $(@D)
	cp $< $@