Gray shading shows up when I print pdf documents

[perfectpdf]

Most pdf documents print cleanly, but some pdf documents print so badly. When I print some documents, gray shading or highlights show up in the background of the texts.

It's definitely invisible on screen, but this happens only when they are printed out.

I think this is because the documents are not texts-based but image-based. I guess images of texts were copied and pasted in the documents.

Is it a matter of the printer itself or the pdf viewer? Don't pdf viewer automatically sense the brightness and print only the texts on the page?

I am not a native speaker of English, so my explanation may sound confusing.

If anybody has a similar problem, please reply.

Thank you in advance!

[Abambo]

I do not know about your native language, but there is a translation feature working fine for most of the languages. But anyway, your request is quite understandable.

Without seeing the file, I can only speculate.

First you do not tell us which pdf viewer you use. If it is Acrobat (some version) your request is at the right place. Other viewers from other companies may react differently, however:

• Acrobat prints faithfully what is contained in the file.
• Some printers may enhance low levels of colour to get them printed. That is not a functionality of Acrobat.
• Scanned text may have some light gray background depending on the scanning procedure.
• As soon as text is present as an image, it is an image and is no more treated as text. Text like vector graphics are rendered at print time so the quality is optimal for the printer used. Graphics is printed as is, with all the defects present.

This should be true also for third party viewers.

[perfectpdf]

I'm using Adobe Acrobat Pro DC. As you mentioned, I think it is because the text in my pdf file is present as an image.

https://drive.google.com/open?id=1qcB3DV4jjzdD0AiBGZi4nNM6Jbb5sTzI

The first page is okay, but from third page, they're not printed cleanly like this.

I tried it again at a different printing shop, and this time was much better even though I could still see dim highlights.

Thank you for your kind reply.

[Abambo]

This part is a JPEG compressed image representing by chance text:

There is nothing that can be done here, except recreating the file with a higher quality scan or even better the text as text...

Any printer and print service provider will print this as is, with all the defects in the print.

[perfectpdf]

I see. I really appreciate your help.

Thank you.

[Abambo]

You're welcome.