#!/bin/bash
# ResizeImageToMatrix384.sh
# Invoke this script in the same directory as the source image files.
# Converts image area to 384 squared pixels or the specified argument.
# Run this by typing: ./ScriptFileName.sh [matrix]
# Or omit matrix size to use default size 384.

# Set target image matrix size X*Y:
squareMatrix=${1:-384}
echo "Matrix size: $squareMatrix"

# Loop through files in the current folder
for file in *.png *.gif *.jpg *.webp; do
   test -e "$file" || continue
   echo 'Processing '"$file"
   # Determine input image dimensions using ImageMagick's identify command
   read inputWidth inputHeight < <(identify -format "%[fx:w] %[fx:h]" "$file")
   # Calculate the scaling factor for the width and height to achieve total pixels
   scaleFactor=$(bc <<< "scale=6; sqrt($squareMatrix*$squareMatrix/$inputWidth/$inputHeight)")
   echo "Scale factor: $scaleFactor" 
   # Calculate the output dimensions and round to the nearest integer.
   outputWidth=$(bc <<< "scale=6; round=($inputWidth*$scaleFactor); scale=0; round/1")
   outputHeight=$(bc <<< "scale=6; round=0.5 + ($inputHeight*$scaleFactor); scale=0; round/1")
   # Resize the input image using ImageMagick's convert command
   convert "$file" -resize "${outputWidth}x${outputHeight}" "${file%.*}-${squareMatrix}.${file##*.}"
   echo
done

echo -en '\a'
read -rs -n1 -t60 -p'Ctrl+C to exit or any key to pause!' || { echo; exit;}
echo -en '\r\aPress Ctrl+C to exit permanent hold!'
sleep infinity