A simple makefile to process a number of input png files into ebook optimised pdf files in a dist directory.

Makefile

inputfiles = $(patsubst %.png,dist/%.pdf,$(wildcard *.png))

rebuild: clean build

build: prepare $(inputfiles) postbuild

dist/%.pdf:
	@convert $(patsubst dist/%.pdf,%.png,$@) tmp/$@
	@gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -sOutputFile=$@ tmp/$@
	@rm tmp/$@

prepare:
	mkdir -p dist
	mkdir -p tmp/dist

postbuild:
	rm -rf tmp

clean:
	rm -rf dist