Makefiles for automating image processing
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This document discusses using makefiles to automate image processing tasks like scaling large sets of images. It presents a problem of needing to repeatedly scale images when target resolutions change. The proposed solution is to use NetPBM image tools and GNU make, which is well-suited for automating transformations from input to output files according to rules. An example makefile is provided that uses find, patsubst and shell commands to scale images in a source directory to a target resolution and save them in a scaled directory.
Makefiles for automating image processing
- 1. Makefiles for Automating Image Processing Shweta Sadawarte CEO Nelkinda Software Craft Pvt Ltd
- 2. Problem Scale a large set (200+) of images to a target resolution. Target resolution might change due to website redesign -> scaling has to be repeated Image set might change - new images might be added later.
- 3. Solution Automatable image processing using NetPBM Automation using GNU make
- 4. Why to use make? Having a set of input files that shall be transformed to a set of output files according to certain rules is the nature of make. The make program uses timestamp to decide which of the files need to be updated.
- 5. SRC_FILES:=$(shell find source/ -name "*.jpg") SCALED_FILES:=$(patsubst source/%.jpg, scaled/%.jpg, $(SRC_FILES)) .PHONY: all all: scale .PRECIOUS: %/ %/: mkdir -p $@ .PHONY: clean clean: $(RM) -r scaled .PHONY: scale scale: $(SCALED_FILES) scaled/%.jpg: source/%.jpg | scaled/ < $< jpegtopnm | pnmscale -xysize 1280 962.4 | pnmtojpeg --quality 85 --progressive > $@