Screen Capture x1 Image Size Under Retina Macs

1. Open “Automator”
2. Select “Service” for “Choose a type for your document”
3. Change “Service receives no input in any application” on top right section of the Automator
4. Drag action “Run Shell Script” from the left pane into the workflow on the right pane
5. Make sure Shell setting is to “/bin/bash”
6. Add the following script to the script section (change the 2nd line setting for SS_PATH to your desktop absolute path) and save:

# the path where screenshots to save
SS_PATH="/Users/vincent/Desktop"
TMP_PATH="/tmp"

# a variable of unix timestamp for screenshot file name
NOW=$(date +%s)

# image format to create, default is png (other options include pdf, jpg, tiff and other formats)
SS_TYPE=png

# name of screenshot
SS_NAME=screenshot$NOW

# full path of screenshot file
SS_1X=$SS_PATH/$SS_NAME.$SS_TYPE
SS_2X=$TMP_PATH/$SS_NAME@2X.$SS_TYPE

# execute screen capture command and save to $SS_2X
screencapture -i -r -t $SS_TYPE $SS_2X

# check if screenshot is existing
if [ -f $SS_2X ]; then

    # get the 50% width of screenshot by sips
    WIDTH=$(($(sips -g pixelWidth $SS_2X | cut -s -d ':' -f 2 | cut -c 2-)/2))

    # scale down by sips
    sips --resampleWidth $WIDTH $SS_2X --out $SS_1X
    
    # copy small one to clipboard by applescript
    # if you hold control key when do capture, causes screen shot 2X to go to clipboard
    osascript -e 'set the clipboard to POSIX file "'$SS_1X'"'
fi

7. Open “System Preferences” > “Keyboard” > “Shortcuts”, find the service you just created and assign hotkey (e.g. Cmd+Shift+5).