"Enhance Scanned Document" leaves a shadow, breaks charts and images

Question

Hi. I found the Enhance scanned document pretty amazing being able to recognize the text and then replace it with quite similar font family. Although I have a particular issue with it. While the image text is replaced with an actual OCR-ed characters, the image underneath remains at some degree. Even choosing the High background removal, it remains underneath, leaving an annoying shadow while also breaking actual images and charts I may have around.

This is the orginial. Actually looks not that bad, still I wanted to try enhancing it:

I tried with Descreen, Deskew and Compression turned off.

The result with Background removal off is below. There is a shadowy artifacts below the text. The chart becomes very low quality even compression is turned off.

Having background removal to High makes the text a little bit more readable, with less shadows still they are quite visible and the result is not the expected. This is at the cost of the chart becomming even more broken.

Any ideas how I can actually enhance the page replacing the original text with the OCR-ed one, leaving no shadows but keep the charts or any other images intact?

I'm attaching the page I have mentioned above.

gary_sc · Answer

Hi Ivan,

There is an adage in photography that you must first best possible image in the camera, then do what you can in the darkroom or Photoshop. In other words, I can make a good photo great in Photoshop but I cannot make a bad photo good in Photoshop.

The image you shared was a completed PDF, not the initial PDF so it's hard to fully see what you are working with. I very seldom use Enhance Background myself because of the issues you are facing. If your scan was OK to good to begin with, Enhance does wonders. But if there are regions in the page where things were not cleaned up enough before you brought it into Enhance Background, there will be issues/problems.

I recently was doing some experiments with this to test how close one could get before it gave poor results, here's one such example:

Note how it shows up in the text region, that's because Acrobat isn't sure what's text and what isn't text. Leaving that blotch is better than inadvertently removing some text as well. But I very very seldom use Enhance Background. Rather I try to fix any issues with the page at the time of scanning. Here's a blog I wrote for Adobe on this subject. [Note: you need to be signed into your Adobe Account to view the blog.]

https://community.adobe.com/t5/adobe-community-professionals/scanning-clean-searchable-pdfs/m-p/4785435?page=1#M89

Lastly, not knowing what scanner you are using, you MAY have problems doing what I'm suggesting in the blog. For many office or home office scanners made in the past several years, manufacturers are providing mindless software that one can simply "click a button" and it works!! Alas, if the problem is that easy, then Enhance Background would fix it as well. But if there are subtleties and issues, the human eye and better software will fix it better.

In the end, there's only so far you can go if the original is in poor condition.

Let me know if any of this doesn't make sense.

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