[BUG]pdf to png font render error

[YuiFn]

Description

Font rendering error when rendering pdf with imageDevice

   target := "taiwen.pdf"
	now := time.Now()
	reader, f, err := model.NewPdfReaderFromFile(target, nil)
	if err != nil {
		log.Fatalf("Could not create reader: %v\n", err)
	}
	defer f.Close()
	numPages, err := reader.GetNumPages()
	if err != nil {
		log.Fatalf("Could not retrieve number of pages: %v\n", err)
	}
	basename := strings.TrimSuffix(filepath.Base(target), filepath.Ext(target))
	device := render.NewImageDevice()
	device.OutputWidth = 800
	for i := 1; i <= numPages; i++ {
		page, err := reader.GetPage(i)
		if err != nil {
			log.Fatalf("Could not retrieve page: %v\n", err)
		}
		outFilename := fmt.Sprintf("%s_%d.png", basename, i)
		if err = device.RenderToPath(page, outFilename); err != nil {
			log.Fatalf("Image rendering error: %v\n", err)
		}
	}

Expected Behavior

all rendering ok

Actual Behavior

use pdf_image_render， see output

Attachments

Include a
AL951611050249.pdf

taiwen.pdf

self-contained reproducible code snippet and PDF file that demonstrates the issue.

[github-actions]

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[zacharysyoung]

I'm seeing this too, but even worse in some cases.

I converted the following PDF to PNGs using the pdf_image_render.go example, and UniPDF v3.34.0:

go run pdf_image_render.go images ~/Downloads/Awesome_Form/ERAP_2_Template.pdf
go: downloading github.com/unidoc/unipdf/v3 v3.34.0
go: downloading github.com/unidoc/pkcs7 v0.1.1-0.20220329190817-dd59b9eba14c
go: downloading golang.org/x/crypto v0.0.0-20220315160706-3147a52a75dd
go: downloading golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e

Here's the PDF:
ERAP_2_Template.pdf

Here's the image for page 1 where some fonts were missed (I'd say... ?):

Here's the image for page 14 with no issues:

[0x-1]

same. seems to be a problem with the render. my blind guess would be fonts.

[sampila]

Hi @YuiFn, @zacharysyoung and @0x-1

We release new UniPDF version to improve font rendering https://github.com/unidoc/unipdf/releases/tag/v3.52.0,

You can try and would be good if you can confirm if the issue is resolved by latest version of UniPDF.

Thanks

[zacharysyoung]

@sampila, yes, 3.52.0 fixed it for me, thank you.

Cheers!

[YuiFn]

@sampila thank you. this work