jpgImages := $(wildcard images.d/*.jpg)
jpgImagesSeefahrt := $(wildcard images.d/seefahrt.d/*.jpg)
pngImages := $(wildcard images.d/*.png)
pngImagesSeefahrt := $(wildcard images.d/seefahrt.d/*.png)

processedJpgImages := $(patsubst images.d/%.jpg, build/images.d/%.jpg, $(jpgImages))
processedJpgImagesSeefahrt := $(patsubst images.d/seefahrt.d/%.jpg, build/images.d/seefahrt.d/%.jpg, $(jpgImagesSeefahrt))
processedPngImages := $(patsubst images.d/%.png, build/images.d/%.png, $(pngImages))
processedPngImagesSeefahrt := $(patsubst images.d/seefahrt.d/%.png, build/images.d/seefahrt.d/%.png, $(pngImagesSeefahrt))

.PHONY: all
all: $(processedJpgImages) $(processedJpgImagesSeefahrt) $(processedPngImages) $(processedPngImagesSeefahrt)

build/%.jpg: %.jpg
	convert $^ -resize x1024 $@

build/%.png: %.png
	convert $^ -resize x1024 $@

.PHONY: echo
echo:
	echo From: $(jpgImagesSeefahrt)
	echo To: $(processedJpgImagesSeefahrt)