Use gulp, and jekyll? me too. I made a handy an automated process for social post images.

social.sh

#!/bin/bash

cd src/assets/images/social/uncompressed  #change directory to exicute script in uncompressed folder
mkdir .tmp     #making temp derectory

cp * .tmp/
mogrify -format jpg -filter Triangle -define filter:support=2 -thumbnail 1200x630! -quality 100 -unsharp 0.25x0.08+8.3+0.045 -dither None -define jpeg:fancy-upsampling=off -interlace none -colorspace sRGB -path .tmp/ .tmp/*.*
mv .tmp/*.jpg .tmp/../../og/; rm -R .tmp/*;

cp * .tmp/
mogrify -format jpg -filter Triangle -define filter:support=2 -thumbnail 1024x512! -quality 100 -unsharp 0.25x0.08+8.3+0.045 -dither None -define jpeg:fancy-upsampling=off -interlace none -colorspace sRGB -path .tmp/ .tmp/*.*
mv .tmp/*.jpg .tmp/../../twitter/; rm -R .tmp/*;

rm -R .tmp #removes temp directory