A macOS script that applies mosaic effects to faces of individuals in photos ( https://doratex.hatenablog.jp/entry/20240327/1711546952 )

mosaicFaces.sh

#!/bin/bash
SCRIPTNAME=$(basename "$0")

function realpath () {
    f=$@
    if [ -d "$f" ]; then
      base=""
      dir="$f"
    else
      base="/$(basename "$f")"
      dir=$(dirname "$f")
    fi
    dir=$(cd "$dir" && /bin/pwd)
    echo "$dir$base"
}

function mosaicFaces () {
    /usr/bin/osascript <<EOF
use framework "Vision"
global CA
set CA to current application

on createNewBitmap(theWidth, theHeight)
    set theSize to {theWidth, theHeight}
    set newImage to CA's NSImage's alloc()'s initWithSize:theSize
    set newBitmap to CA's NSBitmapImageRep's alloc()'s initWithBitmapDataPlanes:(missing value) pixelsWide:theWidth pixelsHigh:theHeight bitsPerSample:8 samplesPerPixel:4 hasAlpha:true isPlanar:false colorSpaceName:(CA's NSDeviceRGBColorSpace) bytesPerRow:0 bitsPerPixel:0
    newBitmap's setSize:theSize
    return newBitmap
end createNewBitmap


on mosaicImage(theNsImage, theScale)
    set filter to CA's CIFilter's filterWithName:"CIPixellate"
    set rep to CA's NSBitmapImageRep's imageRepWithData:(theNsImage's TIFFRepresentation())
    set theCiImage to CA's CIImage's alloc()'s initWithBitmapImageRep:rep
    set theSize to theNsImage's |size|()
    
    filter's setValue:theCiImage forKey:"inputImage"
    filter's setValue:(theSize's width()) * theScale / 1000 forKey:"inputScale"
    
    set outputImage to filter's outputImage()
    set ciImageRep to CA's NSCIImageRep's imageRepWithCIImage:outputImage
    set newNsImage to CA's NSImage's alloc()'s initWithSize:theSize
    newNsImage's addRepresentation:ciImageRep
    
    return newNsImage
end mosaicImage

on mosaicFaces(thePath, theScale)
    set image to CA's NSImage's alloc()'s initWithContentsOfFile:thePath
    
    set rep to CA's NSBitmapImageRep's imageRepWithData:(image's TIFFRepresentation())
    set entireWidth to rep's pixelsWide
    set entireHeight to rep's pixelsHigh
    
    set newImage to CA's NSImage's alloc()'s initWithSize:{entireWidth, entireHeight}
    set newBitmap to my createNewBitmap(entireWidth, entireHeight)
    
    CA's NSGraphicsContext's saveGraphicsState()
    set currentContext to CA's NSGraphicsContext's graphicsContextWithBitmapImageRep:newBitmap
    CA's NSGraphicsContext's setCurrentContext:currentContext
    
    image's drawInRect:{{0, 0}, {entireWidth, entireHeight}} fromRect:(CA's NSZeroRect) operation:(CA's NSCompositingOperationSourceOver) fraction:1.0
    
    set mosaickedImage to my mosaicImage(image, theScale)
    set mosaickedEntireWidth to mosaickedImage's |size|()'s width
    set mosaickedEntireHeight to mosaickedImage's |size|()'s height
    
    set faceDetectionRequest to CA's VNDetectFaceRectanglesRequest's alloc()'s init()
    set requestHandler to (CA's VNImageRequestHandler's alloc's initWithData:(image's TIFFRepresentation) options:(missing value))
    (requestHandler's performRequests:[faceDetectionRequest] |error|:(missing value))
    set results to faceDetectionRequest's results()
    
    repeat with requestResult in results
        set faceBox to CA's NSRectFromCGRect(requestResult's boundingBox)
        set x to item 1 of item 1 of faceBox
        set y to item 2 of item 1 of faceBox
        set width to item 1 of item 2 of faceBox
        set height to item 2 of item 2 of faceBox

        set x1 to x * entireWidth
        set y1 to y * entireHeight
        set width1 to width * entireWidth
        set height1 to height * entireHeight
        set faceRect1 to {{x1, y1}, {width1, height1}}

        set x2 to x * mosaickedEntireWidth
        set y2 to y * mosaickedEntireHeight
        set width2 to width * mosaickedEntireWidth
        set height2 to height * mosaickedEntireHeight
        set faceRect2 to {{x2, y2}, {width2, height2}}

        (mosaickedImage's drawInRect:faceRect1 fromRect:faceRect2 operation:(CA's NSCompositingOperationSourceOver) fraction:1.0)
    end repeat
    
    newImage's addRepresentation:newBitmap
    CA's NSGraphicsContext's restoreGraphicsState()
    
    return newImage
end mosaicFaces

on saveImageAsJPEGFile(image, thePath, compressionFactor, dpi)
    set bitmapRep to CA's NSBitmapImageRep's alloc()'s initWithData:(image's TIFFRepresentation())
    
    set pixelWidth to bitmapRep's pixelsWide
    set pixelHeight to bitmapRep's pixelsHigh
    set pointWidth to bitmapRep's |size|()'s width
    set currentDPI to 72.0 * pixelWidth / pointWidth
    set factor to (dpi / currentDPI)
    bitmapRep's setPixelsWide:(factor * pixelWidth)
    bitmapRep's setPixelsHigh:(factor * pixelHeight)
    
    set jpegProperties to CA's NSMutableDictionary's dictionary()
    jpegProperties's setObject:(compressionFactor) forKey:(CA's NSImageCompressionFactor)
    set jpegData to bitmapRep's representationUsingType:(CA's NSJPEGFileType) |properties|:(jpegProperties)
    set success to jpegData's writeToFile:(thePath) atomically:(true)
    
    return success
end saveImageAsJPEGFile

set thePath to "$1"
set newImage to my mosaicFaces(thePath, $3)
saveImageAsJPEGFile(newImage, "$2", $4, $5)

EOF
}

function usage() {
    echo "Usage: $SCRIPTNAME [--emoji <EMOJI>] [--compression <VALUE>] [--dpi <VALUE>] <INPUT_IMAGE_PATH> <OUTPUT_JPEG_PATH>"
    echo
    echo "Options:"
    echo "  -h, --help      Show help"
    echo "  --scale <VALUE> Set mosaic tile scale (default: 30)"
    echo "  --compression <VALUE>   Set compression factor [from 0.0 (maximum compression) to 1.0 (no compression)] of output image (default: 0.8)"
    echo "  --dpi <VALUE>   Set DPI value of output image (default: 72)"
    echo
}

# parse arguments
declare -a args=("$@")
declare -a params=()

SCALE=30
COMPRESSION=0.8
DPI=72

I=0
while [ $I -lt ${#args[@]} ]; do
    OPT="${args[$I]}"
    case $OPT in
        -h | --help )
            usage
            exit 0
            ;;
        --scale )
            if [[ -z "${args[$(($I+1))]}" ]]; then
                echo "$SCRIPTNAME: option requires an argument -- $OPT" 1>&2
                exit 1
            fi
            SCALE="${args[$(($I+1))]}"
            I=$(($I+1))
            ;;
        --compression )
            if [[ -z "${args[$(($I+1))]}" ]]; then
                echo "$SCRIPTNAME: option requires an argument -- $OPT" 1>&2
                exit 1
            fi
            COMPRESSION="${args[$(($I+1))]}"
            I=$(($I+1))
            ;;
        --dpi )
            if [[ -z "${args[$(($I+1))]}" ]]; then
                echo "$SCRIPTNAME: option requires an argument -- $OPT" 1>&2
                exit 1
            fi
            DPI="${args[$(($I+1))]}"
            I=$(($I+1))
            ;;
        -- | -)
            I=$(($I+1))
            while [ $I -lt ${#args[@]} ]; do
                params+=("${args[$I]}")
                I=$(($I+1))
            done
            break
            ;;
        -*)
            echo "$SCRIPTNAME: illegal option -- '$(echo $OPT | sed 's/^-*//')'" 1>&2
            exit 1
            ;;
        *)
            if [[ ! -z "$OPT" ]] && [[ ! "$OPT" =~ ^-+ ]]; then
                params+=( "$OPT" )
            fi
            ;;
    esac
    I=$(($I+1))
done

# handle invalid arguments
if [ ${#params[@]} -ne 2 ]; then
    echo "$SCRIPTNAME: Specify input and output file names." 1>&2
    echo "Try '$SCRIPTNAME --help' for more information." 1>&2
    exit 1
fi

SUCCESS=$(mosaicFaces "$(realpath ${params[0]})" "$(realpath ${params[1]})" $SCALE $COMPRESSION $DPI)
if [ $SUCCESS = "true" ]; then
    exit 0
else
    exit 1
fi