add webp compression script

imagecompress.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+
+# Run before executing:
+# sudo apt install webp parallel
+
+# Script will compress all images in directory given in the first parameter.
+# JPEGs are lossy compressed, PNGs are losslessly compressed
+# $ ./imagecompress.sh  # current directory
+# $ ./imagecompress.sh opsec/  # specified directory
+# Already compressed WebP image will be kept, it only cares about image/png and image/jpeg mime.
+# Compression commands are run in parallel using all available cores but it can take some time at first.
+
+# WARNING:
+# cwebp by default removes all EXIF, XMP and ICC tags.
+# Images rotated only through Exif tag can have wrong orientation after compression.
+# However we shouldn't have too much Exif here anyways.
+
+DIR="${1:-$(pwd)}"
+
+calculate_size() {
+    du -sh --exclude='.git' "$1" | awk '{print $1}'
+}
+
+initial_size=$(calculate_size "$DIR")
+
+echo "Updating JPEGs"
+
+# Lossy compression for JPEGs
+find "$DIR" -print0 | parallel -0 '
+    [[ $(file --mime-type -b "{}") == "image/jpeg" ]] &&
+    cwebp "{}" -q 65 -m 6 -o "{}"
+'
+
+echo "Updating PNGs"
+
+# Lossless compression for PNGs
+find "$DIR" -print0 | parallel -0 '
+    [[ $(file --mime-type -b "{}") == "image/png" ]] &&
+    cwebp "{}" -q 100 -m 6 -lossless -o "{}"
+'
+
+final_size=$(calculate_size "$DIR")
+echo "Compressed $initial_size -> $final_size