Gray blocks behind text from scanner

[F. McLion]

Hi

How do I get rid of these gray blocks on some locations behind the text or in white space?

- Acrobat Pro DC 2021

- Scanner Canon MG6250 (using Acrobat scan interface and not Canon's)

I have background remove active, otherwise the entire page is gray.

Thanks, McL

[gary_sc]

Hi F. McLion,

This is actually a problem at the scan. It all boils down to "what is white" and "what is the image and not the image" during the scan. When we look at a paper for scanning we immediately focus on the text and ignore any off-white of the page. This is more pronounced when we look at pages (such as newspaper) where the paper is grayer AND there is text bleeding through the other side. There are ways to eliminate that using Photoshop-like tools during the scan process but many new office scanners have eliminated all of those features to make it seem that one button does it all! 

Well, you're observing what happens when one button doesn't do it all. 

I'm providing to you a link to a blog I wrote some time back that goes into detail on how to resolve these issues, but since I wrote this, most manufacturers' scanners are not provided the software to properly deal with the issue. Nonetheless, the issue is that your software is doing OK in removing the background UNTIL it encounters gray area near text that it is not sure what's "text" and what's "background," and leave the background there because of that confusion. 

I suppose one option you do have is to see if you can scan a lighter image. That should make the gray background less gray but at the expense of possibly making any light text disappear. 

Good luck!

Meanwhile, here's the blog:

http://photosbycoyne.com/Gary's_Help/Scanning/clean-scanning.html

[F. McLion]

Thanks Gary. I'll read through your blog.

While in Windows 10 I used to call the Canon driver from Acrobat scan interface and then could use the tools to properly set levels to scan without the background. For a B/W document, that worked a treat.

However, I was too dumb and updated to Windows 11 and now Acrobat is not offering me the "use printer driver" option anymore. For removing Windows 11, I waited too long and the option is gone now - btw that's not the only reason one wants to ditch Windows 11.

The Acrobat option to remove background basically does what it should. However, no matter which level is choosen, it fails to properly remove even on easy and plain B/W document with perfect printing contrast on white paper.

Cheers, Franz

[gary_sc]

Hi Franz,

As a Mac user, I've never even seen a computer with W-11, so please forgive my question here: can you scan using your scanner's software independent from Acrobat? I'd think you should be able to since it has to be on your computer somewhere (otherwise, Acrobat could not access it).

What I suggest is that you scan independently from Acrobat. Save your files as TIF images, and save them into a folder on your desktop (for easy access). Then, when done, open the files from within Acrobat for the OCR process and saving as a PDF. For me, saving a full page of text as a TIF image comes out to about 8 MB, but do not be concerned about that. Once you OCR and save the document, it will be between 80-160 kb depending on the amount of text, size, etc. If the font is small, scan at 600 ppi to obtain better accuracy. The original files may be larger but again, will be much smaller after PDF-ing with OCR. 

Let me know how it goes.

[F. McLion]

I'll try that.

I tried to scan directly to pdf within the Canon driver, since it offers this option. However, the pdf that comes out extremely large and not really usable.

Thanks

[F. McLion]

It's a pity, even the latest version of Acrobat is still not able to create a decent scan of a document with removed paper background.

Hey Acrobat developers, talk to your fellow associates that develop Adobe Scan for the mobile. This app can perfectly create a pdf with removed background!

[gary_sc]

Since Acrobat cannot scan one pixel and relies upon TWAIN to access the scanning software that came with your scanner. I suggest you contact your scanner's manufacturer and work this out with them.

BTW, If you want to do this at any time, in your scanner's software, look for Levels. It will be a Histogram where the left side is the black pixels, the right side is the white pixels, and in the middle is, well, the middle-level (gray level) pixels. Slide the arrow underneath the Histogram on the right side to the left until the background disappears. Then you'll have what you want.

For more details on this, check this out:

https://community.adobe.com/t5/adobe-community-professionals/scanning-clean-searchable-pdfs/m-p/4785...