Merge tag '0.2.3' into develop

Release 0.2.3

.gitignore

@@ -1,2 +1,2 @@
 /dist/
-goptimize
+goptimize*

CHANGELOG.md

@@ -1,5 +1,42 @@
 # Changelog
 
+## [0.2.3]
+
+- Switch to kovidgoyal/imaging to address CVE-2023-36308
+
+
+## [0.2.2]
+
+- Optionally preserve exif data for supported formats
+- Update Go modules
+
+
+## [0.2.1]
+
+- Update core modules
+
+
+## [0.2.0]
+
+- Add threaded option (`-t`) to use all CPU cores
+
+
+## [0.1.0]
+
+- Switch to go mods - go (>= 1.11 required)
+- Switch to axllent/semver for app updating
+
+
+## [0.0.3]
+
+- Detect & skip animated GIFs
+
+
+## [0.0.2]
+
+- Switch to [pflag](https://github.com/spf13/pflag) for better flag management
+
+
 ## [0.0.1]
 
 - Initial release

Makefile

@@ -5,8 +5,7 @@ LDFLAGS=-ldflags "-s -w -X main.version=${VERSION}"
 build = echo "\n\nBuilding $(1)-$(2)" && GOOS=$(1) GOARCH=$(2) go build ${LDFLAGS} -o dist/goptimize_${VERSION}_$(1)_$(2) \
 	&& bzip2 dist/goptimize_${VERSION}_$(1)_$(2)
 
-goptimize: *.go
-	go get github.com/disintegration/imaging
+goptimize: *.go go.*
 	go build ${LDFLAGS} -o goptimize
 	rm -rf /tmp/go-*
 
@@ -21,4 +20,4 @@ release:
 	$(call build,linux,arm)
 	$(call build,linux,arm64)
 	$(call build,darwin,amd64)
-	$(call build,darwin,386)
+	$(call build,darwin,arm64)

README.md

@@ -1,11 +1,12 @@
 # Goptimizer - downscales and optimizes images
 
-Goptimizer is a commandline utility written in Golang. It downscales and optimize existing images JPEG, PNG and Gif files.
+[![Go Report Card](https://goreportcard.com/badge/github.com/axllent/goptimize)](https://goreportcard.com/report/github.com/axllent/goptimize)
 
-Image downscaling is done within Goptimize (`-m <width>x<height>`, see [Usage](#usage-options)), however optimization is done using the following additional tools (if they are installed):
+Goptimizer is a commandline utility written in Golang. It downscales and optimizes JPEG, PNG, GIF, TIFF and BMP files.
 
-- jpegoptim
-- jpegtran (`libjpeg-turbo-progs`)
+Image downscaling/rotation is done within goptimize (`-m <width>x<height>`, see [Usage](#usage-options)), however optimization is done using the following additional tools (if they are installed):
+
+- jpegtran (`libjpeg-turbo-progs`) or jpegoptim
 - optipng
 - pngquant
 - gifsicle
@@ -13,14 +14,16 @@ Image downscaling is done within Goptimize (`-m <width>x<height>`, see [Usage](#
 
 ## Notes
 
-Both `jpegoptim` & `jpegtran` have almost identical optimization, so if both are installed then just `jpegtran` is used for JPG optimization. PNG optimization however will run through both `optipng` & `pngquant` (if installed) as this has definite advantages.
+Both `jpegoptim` & `jpegtran` have almost identical optimization, so if both are installed then just `jpegtran` is used for JPG optimization. PNG optimization however will run through both `optipng` & `pngquant` (if installed) as this can result in better optimization.
 
 It is highly recommended to install the necessary optimization tools, however they are not required to run goptimize.
 
-Goptimize will remove all exif data from JPEG files, auto-rotating those that relied on it.
+Goptimize will remove all exif data from JPEG files, auto-rotating those that depend on it for orientation.
 
 It will also preserve (by default) the file's original modification times (`-p=false` to disable).
 
+Animated GIF files are not supported and automatically get skipped.
+
 
 ## Usage options
 
@@ -28,23 +31,19 @@ It will also preserve (by default) the file's original modification times (`-p=f
 Usage: ./goptimize [options] <images>
 
 Options:
-  -gifsicle string
-        gifsicle binary (default "gifsicle")
-  -jpegoptim string
-        jpegoptim binary (default "jpegoptim")
-  -jpegtran string
-        jpegtran binary (default "jpegtran")
-  -m string
-        downscale to a maximum width & height in pixels (<width>x<height>)
-  -o string
-        output directory (default overwrites original)
-  -optipng string
-        optipng binary (default "optipng")
-  -p    preserve file modification times (default true)
-  -pngquant string
-        pngquant binary (default "pngquant")
-  -q int
-        quality - JPEG only (default 75)
+  -q, --quality int        quality, JPEG only (default 75)
+  -m, --max string         downscale to a maximum width & height in pixels (<width>x<height>)
+  -o, --out string         output directory (default overwrites original)
+  -p, --preserve           preserve file modification times (default true)
+  -t, --threaded           run multi-threaded (use all CPU cores)
+  -u, --update             update to latest release
+  -v, --version            show version number
+  -h, --help               show help
+      --jpegtran string    jpegtran binary (default "jpegtran")
+      --jpegoptim string   jpegoptim binary (default "jpegoptim")
+      --gifsicle string    gifsicle binary (default "gifsicle")
+      --pngquant string    pngquant binary (default "pngquant")
+      --optipng string     optipng binary (default "optipng")
 ```
 
 
@@ -54,3 +53,24 @@ Options:
 - `./goptimize -m 800x800 *` - optimize and downscale all image files to a maximum size of 800x800px
 - `./goptimize -m 1200x0 image.jpg` - optimize and downscale a JPG file to a maximum size of width of 1200px
 - `./goptimize -o out/ image.jpg` - optimize a JPG file and save it to `out/`
+
+
+## Install
+
+Download the appropriate binary from the [releases](https://github.com/axllent/goptimize/releases/latest), or if you have golang installed 
+
+
+### Build requirements
+
+Go >= 1.21 required.
+
+```
+go get github.com/axllent/goptimize
+```
+
+## TODO
+
+Some ideas for the future:
+
+- Dry run
+- Option to copy exif data (how?)

exifcopy.go

@@ -0,0 +1,171 @@
+// https://stackoverflow.com/a/76779756
+package main
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"os"
+)
+
+const (
+	soi       = 0xD8
+	eoi       = 0xD9
+	sos       = 0xDA
+	exif      = 0xE1
+	copyright = 0xEE
+	comment   = 0xFE
+)
+
+func isMetaTagType(tagType byte) bool {
+	// Adapt as needed
+	return tagType == exif || tagType == copyright || tagType == comment
+}
+
+func copySegments(dst *bufio.Writer, src *bufio.Reader, filterSegment func(tagType byte) bool) error {
+	var buf [2]byte
+	_, err := io.ReadFull(src, buf[:])
+	if err != nil {
+		return err
+	}
+	if buf != [2]byte{0xFF, soi} {
+		return errors.New("expected SOI")
+	}
+	for {
+		_, err := io.ReadFull(src, buf[:])
+		if err != nil {
+			return err
+		}
+		if buf[0] != 0xFF {
+			return errors.New("invalid tag type")
+		}
+		if buf[1] == eoi {
+			// Hacky way to check for EOF
+			_, err := src.Read(buf[:1])
+			if err != nil && err != io.EOF {
+				return err
+			}
+			// don't return an error as some cameras add the exif data at the end.
+			// if n > 0 {
+			// 	return errors.New("EOF expected after EOI")
+			// }
+			return nil
+		}
+		sos := buf[1] == 0xDA
+		filter := filterSegment(buf[1])
+		if filter {
+			_, err = dst.Write(buf[:])
+			if err != nil {
+				return err
+			}
+		}
+
+		_, err = io.ReadFull(src, buf[:])
+		if err != nil {
+			return err
+		}
+		if filter {
+			_, err = dst.Write(buf[:])
+			if err != nil {
+				return err
+			}
+		}
+
+		// Note: Includes the length, but not the tag, so subtract 2
+		tagLength := ((uint16(buf[0]) << 8) | uint16(buf[1])) - 2
+		if filter {
+			_, err = io.CopyN(dst, src, int64(tagLength))
+		} else {
+			_, err = src.Discard(int(tagLength))
+		}
+		if err != nil {
+			return err
+		}
+		if sos {
+			// Find next tag `FF xx` in the stream where `xx != 0` to skip ECS
+			// See https://stackoverflow.com/questions/2467137/parsing-jpeg-file-format-format-of-entropy-coded-segments-ecs
+			for {
+				bytes, err := src.Peek(2)
+				if err != nil {
+					return err
+				}
+				if bytes[0] == 0xFF {
+					data, rstMrk := bytes[1] == 0, bytes[1] >= 0xD0 && bytes[1] <= 0xD7
+					if !data && !rstMrk {
+						break
+					}
+				}
+				if filter {
+					err = dst.WriteByte(bytes[0])
+					if err != nil {
+						return err
+					}
+				}
+				_, err = src.Discard(1)
+				if err != nil {
+					return err
+				}
+			}
+		}
+	}
+}
+
+func copyMetadata(outImagePath, imagePath, metadataImagePath string) error {
+	outFile, err := os.Create(outImagePath)
+	if err != nil {
+		return err
+	}
+	defer outFile.Close()
+	writer := bufio.NewWriter(outFile)
+
+	imageFile, err := os.Open(imagePath)
+	if err != nil {
+		return err
+	}
+	defer imageFile.Close()
+	imageReader := bufio.NewReader(imageFile)
+
+	metaFile, err := os.Open(metadataImagePath)
+	if err != nil {
+		return err
+	}
+	defer metaFile.Close()
+	metaReader := bufio.NewReader(metaFile)
+
+	_, err = writer.Write([]byte{0xFF, soi})
+	if err != nil {
+		return err
+	}
+
+	// Copy metadata segments
+	// It seems that they need to come first!
+	err = copySegments(writer, metaReader, isMetaTagType)
+	if err != nil {
+		return err
+	}
+	// Copy all non-metadata segments
+	err = copySegments(writer, imageReader, func(tagType byte) bool {
+		return !isMetaTagType(tagType)
+	})
+	if err != nil {
+		return err
+	}
+
+	_, err = writer.Write([]byte{0xFF, eoi})
+	if err != nil {
+		return err
+	}
+
+	// Flush the writer, otherwise the last couple buffered writes (including the EOI) won't get written!
+	return writer.Flush()
+}
+
+func exifCopy(fromPath, toPath string) error {
+	copyPath := toPath + "~"
+	err := os.Rename(toPath, copyPath)
+	if err != nil {
+		return err
+	}
+	defer os.Remove(copyPath)
+	return copyMetadata(toPath, copyPath, fromPath)
+}

go.mod

@@ -0,0 +1,14 @@
+module github.com/axllent/goptimize
+
+go 1.21
+
+toolchain go1.22.2
+
+require (
+	github.com/axllent/ghru v1.2.1
+	github.com/kovidgoyal/imaging v1.6.3
+	github.com/spf13/pflag v1.0.5
+	golang.org/x/image v0.15.0
+)
+
+require github.com/axllent/semver v0.0.1 // indirect

go.sum

@@ -0,0 +1,10 @@
+github.com/axllent/ghru v1.2.1 h1:PuJQQeILJJ42O9nvjTwObWQGZDyZ9/F71st9jNAqgoU=
+github.com/axllent/ghru v1.2.1/go.mod h1:YgznIILRJpnII5x8N080q/G8Milzk3sy9Sh4dV1eGQw=
+github.com/axllent/semver v0.0.1 h1:QqF+KSGxgj8QZzSXAvKFqjGWE5792ksOnQhludToK8E=
+github.com/axllent/semver v0.0.1/go.mod h1:2xSPzvG8n9mRfdtxSvWvfTfQGWfHsMsHO1iZnKATMSc=
+github.com/kovidgoyal/imaging v1.6.3 h1:iNPpv7ygiaB/NOztc6APMT7yr9UwBS+rOZwIbAdtyY8=
+github.com/kovidgoyal/imaging v1.6.3/go.mod h1:sHvcLOOVhJuto2IoNdPLEqnAUoL5ZfHEF0PpNH+882g=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+golang.org/x/image v0.15.0 h1:kOELfmgrmJlw4Cdb7g/QGuB3CvDrXbqEIww/pNtNBm8=
+golang.org/x/image v0.15.0/go.mod h1:HUYqC05R2ZcZ3ejNQsIHQDQiwWM4JBqmm6MKANTp4LE=

goptimize.go

@@ -2,17 +2,17 @@ package main
 
 import (
 	"fmt"
+	"image"
 	"image/gif"
 	"image/jpeg"
 	"image/png"
 	"io"
-	"io/ioutil"
 	"math"
 	"os"
 	"os/exec"
 	"path/filepath"
 
-	"github.com/disintegration/imaging"
+	"github.com/kovidgoyal/imaging"
 	"golang.org/x/image/bmp"
 	"golang.org/x/image/tiff"
 )
@@ -22,31 +22,47 @@ func Goptimize(file string) {
 	info, err := os.Stat(file)
 
 	if err != nil {
-		fmt.Printf("%s doesn't exist\n", file)
+		fmt.Printf("Error: %s doesn't exist\n", file)
 		return
 	}
 
 	if !info.Mode().IsRegular() {
-		// not a file
-		fmt.Printf("%s is not a file\n", file)
+		fmt.Printf("Error: %s is not a file\n", file)
 		return
 	}
 
-	// open original, rotate if neccesary
-	src, err := imaging.Open(file, imaging.AutoOrientation(true))
+	var src image.Image
 
-	if err != nil {
-		fmt.Printf("%v (%s)\n", err, file)
-		return
+	if !copyExif {
+		// rotate if necessary
+		src, err = imaging.Open(file, imaging.AutoOrientation(true))
+		if err != nil {
+			fmt.Printf("Error: %v (%s)\n", err, file)
+			return
+		}
+	} else {
+		src, err = imaging.Open(file)
+		if err != nil {
+			fmt.Printf("Error: %v (%s)\n", err, file)
+			return
+		}
 	}
 
 	format, err := imaging.FormatFromFilename(file)
 
 	if err != nil {
-		fmt.Printf("Cannot detect format: %v\n", err)
+		fmt.Printf("Error: cannot detect format: %v\n", err)
 		return
 	}
 
+	if format.String() == "GIF" {
+		// return if GIF is animated - unsupported
+		if err := IsGIFAnimated(file); err != nil {
+			fmt.Printf("Error: animated GIF not supported (%v)\n", file)
+			return
+		}
+	}
+
 	outFilename := filepath.Base(file)
 	outDir := filepath.Dir(file)
 	dstFile := filepath.Join(outDir, outFilename)
@@ -60,7 +76,7 @@ func Goptimize(file string) {
 	srcW := srcBounds.Dx()
 	srcH := srcBounds.Dy()
 
-	// Ensure scaling does not upscale image
+	// do not upscale image
 	imgMaxW := maxWidth
 	if imgMaxW == 0 || imgMaxW > srcW {
 		imgMaxW = srcW
@@ -76,27 +92,28 @@ func Goptimize(file string) {
 	resultW := dstBounds.Dx()
 	resultH := dstBounds.Dy()
 
-	tmpFile, err := ioutil.TempFile(os.TempDir(), "Goptimized-")
+	tmpFile, err := os.CreateTemp(os.TempDir(), "Goptimized-")
 
 	if err != nil {
-		fmt.Printf("Cannot create temporary file: %v\n", err)
+		fmt.Printf("Error: cannot create temporary file: %v\n", err)
 		return
 	}
 
 	defer os.Remove(tmpFile.Name())
 
-	if format.String() == "JPEG" {
+	switch imgType := format.String(); imgType {
+	case "JPEG":
 		err = jpeg.Encode(tmpFile, resized, &jpeg.Options{Quality: quality})
-	} else if format.String() == "PNG" {
+	case "PNG":
 		err = png.Encode(tmpFile, resized)
-	} else if format.String() == "GIF" {
+	case "GIF":
 		err = gif.Encode(tmpFile, resized, nil)
-	} else if format.String() == "TIFF" {
+	case "TIFF":
 		err = tiff.Encode(tmpFile, resized, nil)
-	} else if format.String() == "BMP" {
+	case "BMP":
 		err = bmp.Encode(tmpFile, resized)
-	} else {
-		fmt.Printf("Unsupported file type %s\n", file)
+	default:
+		fmt.Printf("Error: unsupported file type (%s)\n", file)
 		return
 	}
 
@@ -112,23 +129,30 @@ func Goptimize(file string) {
 	// so we can modify it with system processes
 	tmpFile.Close()
 
-	// Run through optimizers
+	// run through optimizers
 	if format.String() == "JPEG" {
 		// run one or the other, running both has no advantage
 		if jpegtran != "" {
-			RunOptimiser(tmpFilename, true, jpegtran, "-optimize", "-outfile")
+			RunOptimizer(tmpFilename, true, jpegtran, "-optimize", "-outfile")
 		} else if jpegoptim != "" {
-			RunOptimiser(tmpFilename, false, jpegoptim, "-f", "-s", "-o")
+			RunOptimizer(tmpFilename, false, jpegoptim, "-f", "-s", "-o")
+		}
+
+		if copyExif {
+			if err := exifCopy(file, tmpFilename); err != nil {
+				fmt.Printf("Error copying exif data: %v (%s)\n", err, file)
+				return
+			}
 		}
 	} else if format.String() == "PNG" {
 		if pngquant != "" {
-			RunOptimiser(tmpFilename, true, pngquant, "-f", "--output")
+			RunOptimizer(tmpFilename, true, pngquant, "-f", "--output")
 		}
 		if optipng != "" {
-			RunOptimiser(tmpFilename, true, optipng, "-out")
+			RunOptimizer(tmpFilename, true, optipng, "-out")
 		}
 	} else if format.String() == "GIF" && gifsicle != "" {
-		RunOptimiser(tmpFilename, true, gifsicle, "-o")
+		RunOptimizer(tmpFilename, true, gifsicle, "-o")
 	}
 
 	// re-open modified temporary file
@@ -166,7 +190,7 @@ func Goptimize(file string) {
 		defer out.Close()
 
 		if _, err := io.Copy(out, tmpFile); err != nil {
-			fmt.Printf("Error ovewriting original file: %v\n", err)
+			fmt.Printf("Error overwriting original file: %v\n", err)
 			return
 		}
 
@@ -179,7 +203,7 @@ func Goptimize(file string) {
 
 		fmt.Printf("Goptimized %s (%dx%d %s > %s %v%%)\n", dstFile, resultW, resultH, ByteCountSI(srcSize), ByteCountSI(dstSize), savedPercent)
 	} else {
-		// If the output directory is not the same,
+		// if the output directory is not the same,
 		// then write a copy of the original file
 		if outputDir != "" {
 			out, err := os.Create(dstFile)
@@ -215,11 +239,11 @@ func Goptimize(file string) {
 
 }
 
-// RunOptimiser will run the specified command on a copy of the temporary file,
+// RunOptimizer will run the specified command on a copy of the temporary file,
 // and overwrite it if the output is smaller than the original
-func RunOptimiser(src string, outFileArg bool, args ...string) {
+func RunOptimizer(src string, outFileArg bool, args ...string) {
 	// create a new temp file
-	tmpFile, err := ioutil.TempFile(os.TempDir(), "Goptimized-")
+	tmpFile, err := os.CreateTemp(os.TempDir(), "Goptimized-")
 
 	if err != nil {
 		fmt.Printf("Cannot create temporary file: %v\n", err)
@@ -289,3 +313,21 @@ func ByteCountSI(b int64) string {
 	}
 	return fmt.Sprintf("%.1f%cB", float64(b)/float64(div), "kMGTPE"[exp])
 }
+
+// IsGIFAnimated will return an error if the GIF file has more than 1 frame
+func IsGIFAnimated(gifFile string) error {
+	file, _ := os.Open(gifFile)
+	defer file.Close()
+
+	g, err := gif.DecodeAll(file)
+	if err != nil {
+		return err
+	}
+
+	// Single frame = OK
+	if len(g.Image) == 1 {
+		return nil
+	}
+
+	return fmt.Errorf("Animated gif")
+}

main.go

@@ -1,14 +1,16 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 	"os"
 	"os/exec"
 	"regexp"
+	"runtime"
 	"strconv"
+	"sync"
 
-	"github.com/axllent/gitrel"
+	"github.com/axllent/ghru"
+	"github.com/spf13/pflag"
 )
 
 var (
@@ -22,15 +24,21 @@ var (
 	optipng          string
 	pngquant         string
 	gifsicle         string
+	copyExif         bool
+	threads          = 1
 	version          = "dev"
 )
 
 func main() {
+	// set up new flag instance
+	flag := pflag.NewFlagSet(os.Args[0], pflag.ExitOnError)
+
 	// set the default help
 	flag.Usage = func() {
 		fmt.Println("Goptimize - downscales and optimizes images")
 		fmt.Printf("\nUsage: %s [options] <images>\n", os.Args[0])
 		fmt.Println("\nOptions:")
+		flag.SortFlags = false
 		flag.PrintDefaults()
 		fmt.Println("\nExamples:")
 		fmt.Printf("  %s image.png\n", os.Args[0])
@@ -38,33 +46,38 @@ func main() {
 		fmt.Printf("  %s -o out/ -q 90 -m 1600x1600 *.jpg\n", os.Args[0])
 
 		fmt.Println("\nDetected optimizers:")
-		if err := displayDelectedOptimizer("jpegtran ", jpegtran); err != nil {
-			displayDelectedOptimizer("jpegoptim", jpegoptim)
+		if err := displayDetectedOptimizer("jpegtran ", jpegtran); err != nil {
+			displayDetectedOptimizer("jpegoptim", jpegoptim)
 		}
-		displayDelectedOptimizer("optipng  ", optipng)
-		displayDelectedOptimizer("pngquant ", pngquant)
-		displayDelectedOptimizer("gifsicle ", gifsicle)
+		displayDetectedOptimizer("optipng  ", optipng)
+		displayDetectedOptimizer("pngquant ", pngquant)
+		displayDetectedOptimizer("gifsicle ", gifsicle)
 	}
 
 	var maxSizes string
-	var update, showversion bool
+	var multiThreaded, update, showversion, showhelp bool
 
-	flag.IntVar(&quality, "q", 75, "quality - JPEG only")
-	flag.StringVar(&outputDir, "o", "", "output directory (default overwrites original)")
-	flag.BoolVar(&preserveModTimes, "p", true, "preserve file modification times")
-	flag.StringVar(&maxSizes, "m", "", "downscale to a maximum width & height in pixels (<width>x<height>)")
-	flag.BoolVar(&update, "u", false, "update to latest release")
-	flag.BoolVar(&showversion, "v", false, "show version number")
+	flag.IntVarP(&quality, "quality", "q", 75, "quality, JPEG only")
+	flag.StringVarP(&maxSizes, "max", "m", "", "downscale to a maximum width & height in pixels (<width>x<height>)")
+	flag.StringVarP(&outputDir, "out", "o", "", "output directory (default overwrites original)")
+	flag.BoolVarP(&preserveModTimes, "preserve", "p", true, "preserve file modification times")
+	flag.BoolVarP(&copyExif, "exif", "e", false, "copy exif data")
+	flag.BoolVarP(&update, "update", "u", false, "update to latest release")
+	flag.BoolVarP(&multiThreaded, "threaded", "t", false, "run multi-threaded (use all CPU cores)")
+	flag.BoolVarP(&showversion, "version", "v", false, "show version number")
+	flag.BoolVarP(&showhelp, "help", "h", false, "show help")
 
 	// third-party optimizers
-	flag.StringVar(&gifsicle, "gifsicle", "gifsicle", "gifsicle binary")
-	flag.StringVar(&jpegoptim, "jpegoptim", "jpegoptim", "jpegoptim binary")
 	flag.StringVar(&jpegtran, "jpegtran", "jpegtran", "jpegtran binary")
-	flag.StringVar(&optipng, "optipng", "optipng", "optipng binary")
+	flag.StringVar(&jpegoptim, "jpegoptim", "jpegoptim", "jpegoptim binary")
+	flag.StringVar(&gifsicle, "gifsicle", "gifsicle", "gifsicle binary")
 	flag.StringVar(&pngquant, "pngquant", "pngquant", "pngquant binary")
+	flag.StringVar(&optipng, "optipng", "optipng", "optipng binary")
 
-	// parse flags
-	flag.Parse()
+	flag.SortFlags = false
+
+	// parse args excluding os.Args[0]
+	flag.Parse(os.Args[1:])
 
 	// detect optimizer paths
 	gifsicle, _ = exec.LookPath(gifsicle)
@@ -73,22 +86,27 @@ func main() {
 	optipng, _ = exec.LookPath(optipng)
 	pngquant, _ = exec.LookPath(pngquant)
 
+	if showhelp {
+		flag.Usage()
+		os.Exit(1)
+	}
+
 	if showversion {
 		fmt.Println(fmt.Sprintf("Version: %s", version))
-		latest, _, _, err := gitrel.Latest("axllent/goptimize", "goptimize")
-		if err == nil && latest != version {
+		latest, _, _, err := ghru.Latest("axllent/goptimize", "goptimize")
+		if err == nil && ghru.GreaterThan(latest, version) {
 			fmt.Printf("Update available: %s\nRun `%s -u` to update.\n", latest, os.Args[0])
 		}
 		return
 	}
 
 	if update {
-		rel, err := gitrel.Update("axllent/goptimize", "goptimize", version)
+		rel, err := ghru.Update("axllent/goptimize", "goptimize", version)
 		if err != nil {
 			fmt.Println(err)
 			os.Exit(1)
 		}
-		fmt.Printf("Updated %s to version %s", os.Args[0], rel)
+		fmt.Printf("Updated %s to version %s\n", os.Args[0], rel)
 		return
 	}
 
@@ -125,13 +143,38 @@ func main() {
 		}
 	}
 
-	for _, img := range args {
-		Goptimize(img)
+	if multiThreaded {
+		threads = runtime.NumCPU()
 	}
+
+	processChan := make(chan string)
+
+	wg := &sync.WaitGroup{} // Signal to main goroutine that worker goroutines are working/done working
+	wg.Add(threads)
+
+	for i := 0; i < threads; i++ {
+		go func() {
+			for nextFile := range processChan {
+				Goptimize(nextFile)
+			}
+			// Channel was closed, so we finished this goroutine.
+			wg.Done() // Let main goroutine know we are done.
+		}()
+	}
+
+	for _, img := range args {
+		processChan <- img
+	}
+
+	// Close the channel.  This tells the worker goroutines that they can be done.
+	close(processChan)
+
+	// Wait for all worker goroutines to finish processing the IPs
+	wg.Wait()
 }
 
-// displayDelectedOptimizer prints whether the optimizer was found
-func displayDelectedOptimizer(name, bin string) error {
+// displayDetectedOptimizer prints whether the optimizer was found
+func displayDetectedOptimizer(name, bin string) error {
 	exe, err := exec.LookPath(bin)
 	if err != nil {
 		return err