Changing BG color on PDF e-readers

[ittiandro]

My e-book reader is EZ-PDF Reader and the books I read with it are PDF Scanned. This is the best reader I could find after several trials, but unfortunately, unlike EPUB e-readers where I can change the background color or texture, the background of the PDF page is a bluish hue which I cannot change. Not even with the latest version 2.5.3.1. which claims to do it!
Is there any application, which allows me to select background colors for PDF format , no matter what e-reader I use? Alternatively, is there any PDF Reader which allows this? Would hate to move away from EzPdf Reader, though, because it was the best I could find among a ton I tried! My Android tablet is a D2-912 pad.

Thanks

Ittiandro

[jackie_w]

I think the problem may be with the scanned image PDFs. If the images taken of each page have a bluish background then that's what you'll see. A 'proper' text-based PDF can be displayed in EZ-PDF night-mode with no problems that I can see. I don't know of a PDF reading app which can change images on-the-fly, but that doesn't mean no app exists, of course

[markom]

Originally Posted by ittiandro

My e-book reader is EZ-PDF Reader and the books I read with it are PDF Scanned. This is the best reader I could find after several trials, but unfortunately, unlike EPUB e-readers where I can change the background color or texture, the background of the PDF page is a bluish hue which I cannot change. Not even with the latest version 2.5.3.1. which claims to do it!
Is there any application, which allows me to select background colors for PDF format , no matter what e-reader I use? Alternatively, is there any PDF Reader which allows this? Would hate to move away from EzPdf Reader, though, because it was the best I could find among a ton I tried! My Android tablet is a D2-912 pad.

Thanks

Ittiandro

You can change background color or text color in some pdf readers but for textual pdfs only, not scanned pdfs.

There are free pdf readers there that allow sepia effects for scanned pdfs on iOS so probably for Android too.

iPad for example has problem with CMYK profiled pdf (those for paper print) because it doesn't convert CMYK to RGB accurately.

So, for CMYK profiled pdf to be accurately rendered on iPad we should change pdf color profile from CMYK to Adobe RGB or sRGB, using Adobe Acrobat or some other tool.

So, I guess you should find some tool that can calibrate pdf colors beforehand or you can simply export scanned pdf to images and then use Photoshop or some other image editor to calibrate colors, converting those images back to pdf afterwards, or there may be some color calibration app for your tablet screen(rooted or unrooted).

You can also try night mode, white letters on black background.

If you don't need color for the majority of the pages there, you can turn pdf to grayscale beforehand using k2pdfopt app, at the same time increasing the contrast, darkening the letters with gamma correction and brightening a possibly grayish background using whitethreshold command.