main.go

package main

import (
	"flag"
	"fmt"
	"image/png"
	"log"
	"os"
	"path/filepath"

	"github.com/unidoc/unipdf/v3/extractor"
	"github.com/unidoc/unipdf/v3/model"
)

func main() {
	home, _ := os.UserHomeDir()
	inputPath := flag.String("input", "./input.pdf", "PDF file path")
	outputPath := flag.String("output", filepath.Join(home, "Downloads"), "Output zip file path")
	flag.Parse()
	err := extractPDFImage(*inputPath, *outputPath)
	if err != nil {
		log.Fatalf("Error: %v\n", err)
	}
}

func extractPDFImage(inputPath, outputPath string) error {
	pdfReader, f, err := model.NewPdfReaderFromFile(inputPath, nil)
	if err != nil {
		return err
	}
	defer f.Close()
	numPages, err := pdfReader.GetNumPages()
	if err != nil {
		return err
	}
	log.Printf("Loading %d pages\n", numPages)
	inputPathHash := fmt.Sprintf("%x", inputPath)
	for i := 0; i < numPages; i++ {
		err2 := extractPageImage(pdfReader, i, inputPathHash, outputPath)
		if err2 != nil {
			return err2
		}
	}
	return nil
}

func extractPageImage(pdfReader *model.PdfReader, i int, inputPathHash string, outputPath string) error {
	page, err := pdfReader.GetPage(i + 1)
	if err != nil {
		return err
	}
	pageReader, err := extractor.New(page)
	if err != nil {
		return err
	}
	images, err := pageReader.ExtractPageImages(&extractor.ImageExtractOptions{
		IncludeInlineStencilMasks: false,
	})
	if err != nil {
		return err
	}
	log.Printf("Page %d: %d images\n", i+1, len(images.Images))
	for idx, img := range images.Images {
		imgName := fmt.Sprintf("%s_%d_%d.png", inputPathHash, i+1, idx+1)
		err2 := savePNG(imgName, outputPath, img)
		if err2 != nil {
			return err2
		}
	}
	return nil
}

func savePNG(imgName, outputPath string, img extractor.ImageMark) error {
	imgPath := filepath.Join(outputPath, imgName)
	log.Printf("Saving image to %s\n", imgPath)
	imgFile, err := os.Create(imgPath)
	if err != nil {
		return err
	}
	defer imgFile.Close()
	image, err := img.Image.ToGoImage()
	if err != nil {
		return err
	}
	err = png.Encode(imgFile, image)
	if err != nil {
		return err
	}
	return nil
}