Can't invert a pdf color into white text on black

[Renq41883338]

Hi,

I'm trying to invert the text color on the file downloaded from here into white text on a black background color. Here are the things I tried:

1) Edit > Preferences > Accessibility > Document Color Options > select check box Replace Document Colors > select Use Windows Color Scheme

When I tried to invert windows color scheme, the pdf file all turned black (Text + background).

2) Edit > Preferences > Accessibility > Document Color Options > select check box Replace Document Colors > select Use High-Contrast Colors > select High-Contrast Color Combination : White Text on Black.

When I did this, the text stays black yet the background changed from white to black. So the pdf file becomes, again, fully dark.

The pdf text has been scanned, OCR and it is searchable. I can select the text.

Where did I went wrong?

[Bernd Alheit]

What OCR options did you use?

[Renq41883338]

I haven't edited anything. It's been put to OCR from the download source. Seems to me that it has been scanned and done OCR to it, since I cannot use text reflow option properly in this document either, as it becomes disproportional, irregular when using it..And I noticed some text were missing when using reflow when you zoom in too much. And that never happened to me on normal searchable pdf files.

*Sorry I don't actually know what has been done to the file. Whether it has been OCR or not, scanned or not, I don't really know. I was just guessing. But I can't edit my op post now. Yet according to the uploader in his file description in the link above, the file has indeed been OCR and scanned. But I don't know which option he used.