add format copy option

internal/pkg/converter/converter.go

@@ -15,6 +15,7 @@ import (
 	"reflect"
 	"regexp"
 	"runtime"
+	"slices"
 	"strings"
 	"time"
 
@@ -131,7 +132,7 @@ func (c *Converter) InitParse() {
 	c.AddStringParam(&c.Options.Image.View.Color.Foreground, "foreground-color", c.Options.Image.View.Color.Foreground, "Foreground color in hexadecimal format RGB. Black=000, White=FFF")
 	c.AddStringParam(&c.Options.Image.View.Color.Background, "background-color", c.Options.Image.View.Color.Background, "Background color in hexadecimal format RGB. Black=000, White=FFF, Light Gray=DDD, Dark Gray=777")
 	c.AddBoolParam(&c.Options.Image.Resize, "resize", c.Options.Image.Resize, "Reduce image size if exceed device size")
-	c.AddStringParam(&c.Options.Image.Format, "format", c.Options.Image.Format, "Format of output images: jpeg (lossy), png (lossless)")
+	c.AddStringParam(&c.Options.Image.Format, "format", c.Options.Image.Format, "Format of output images: jpeg (lossy), png (lossless), copy (no processing)")
 	c.AddFloatParam(&c.Options.Image.View.AspectRatio, "aspect-ratio", c.Options.Image.View.AspectRatio, "Aspect ratio (height/width) of the output\n -1 = same as device\n  0 = same as source\n1.6 = amazon advice for kindle")
 	c.AddBoolParam(&c.Options.Image.View.PortraitOnly, "portrait-only", c.Options.Image.View.PortraitOnly, "Portrait only: force orientation to portrait only.")
 	c.AddIntParam(&c.Options.TitlePage, "titlepage", c.Options.TitlePage, "Title page\n0 = never\n1 = always\n2 = only if epub is split")
@@ -379,8 +380,8 @@ func (c *Converter) Validate() error {
 	}
 
 	// Format
-	if !(c.Options.Image.Format == "jpeg" || c.Options.Image.Format == "png") {
+	if !slices.Contains([]string{"jpeg", "png", "copy"}, c.Options.Image.Format) {
-		return errors.New("format should be jpeg or png")
+		return errors.New("format should be jpeg, png or copy")
 	}
 
 	// Aspect Ratio

internal/pkg/epubimageprocessor/loader.go

@@ -53,7 +53,7 @@ func (e EPUBImageProcessor) isSupportedImage(path string) bool {
 	return false
 }
 
-// Load images from input
+// load images from input
 func (e EPUBImageProcessor) load() (totalImages int, output chan task, err error) {
 	fi, err := os.Stat(e.Input)
 	if err != nil {

internal/pkg/epubimageprocessor/passthrough.go

@@ -0,0 +1,8 @@
+package epubimageprocessor
+
+import "github.com/celogeek/go-comic-converter/v3/internal/pkg/epubimage"
+
+func (e EPUBImageProcessor) PassThrough() (images []epubimage.EPUBImage, err error) {
+	images = make([]epubimage.EPUBImage, 0)
+	return images, nil
+}

pkg/epub/epub.go

@@ -3,6 +3,7 @@ package epub
 
 import (
 	"archive/zip"
+	"errors"
 	"fmt"
 	"math"
 	"path/filepath"
@@ -202,12 +203,23 @@ func (e epub) writeTitleImage(wz epubzip.EPUBZip, img epubimage.EPUBImage, title
 
 // extract image and split it into part
 func (e epub) getParts() (parts []epubPart, imgStorage epubzip.StorageImageReader, err error) {
-	images, err := e.imageProcessor.Load()
+	images, err := func() ([]epubimage.EPUBImage, error) {
+		if e.EPUBOptions.Image.Format == "copy" {
+			return e.imageProcessor.PassThrough()
+		} else {
+			return e.imageProcessor.Load()
+		}
+	}()
 
 	if err != nil {
 		return
 	}
 
+	if len(images) == 0 {
+		err = errors.New("no image found")
+		return
+	}
+
 	// sort result by id and part
 	sort.Slice(images, func(i, j int) bool {
 		if images[i].Id == images[j].Id {