Image Optimization

Last updated: 2020-05-03

`mozjpeg`

Installation

Via MacPorts

sudo port install mozjpeg

To fix missing dependencies after installing mozjpeg, copy scripts to local bin:

# Find where mozjpeg is installed
port contents mozjpeg

# example:
Port mozjpeg contains:
  /opt/local/bin/cjpeg
  /opt/local/bin/djpeg
  ...

# cd to that location and copy scripts

cd /opt/local/bin

cp cjpeg /usr/local/bin/mozcjpeg
cp djpeg /usr/local/bin/mozdjpeg

reference

Optipng

A quick example: cd into the directory with image(s) to be optimized and:

find . -name "*.png" -exec optipng -o7 {} \;

Jpegopti

An exmaple with a dry-run option enabled:

find . -name "*.jpg" -exec jpegoptim -m60 -o -p -n --strip-all {} \;

Run the same command for real:

find . -name "*.jpg" -exec jpegoptim -m60 -o -p --strip-all {} \;

PngQuant

pngquant.org

# Run the script
$ ./pngquant list_file_names

# Removed custom suffix
$ ./pngquant --ext .png list_file_names

# Force overwrite of source files
$ ./pngquant --force list_file_names

# Combine both options
$ ./pngquant --ext .png --force list_file_names

`sips` Image Conversion Tool

Batch Convert PNG to JPG

mkdir jpegs; sips -s format jpeg *.* --out jpegs

Batch Convert JPG to PNG

mkdir pngs; sips -s format png *.* --out pngs

Explanation

mkdir creates a new folder
sips -s format sets the format you want to change the files to
--out sets the directory you want to save the converted files to

Batch Resize Images

sips -Z 640 *.jpg

Check Image Dimensions

sips -g pixelHeight -g pixelWidth *

Single File Conversion

To convert a single image with sips, use the following command string syntax:

sips -s format [image type] [file name] --out [ouptut file]

Example:

sips -s format png test.jpg --out test.png

Batch Image Conversion

for i in [filename]; do sips -s format [image type] $i --out [destination]/$i.[extension];done