hoe krijg ik pdf documenten helder der bvb wi witter en tekst zwarter?

@Theo Adema that's a camera issue what you posted. I would actually use Adobe Scan from the App or Play Store for your mobile device. I would only use the Adobe Scan as the only PDF scanner for a mobile device. It will scan (takes a photo) and can save the receipt as a PDF and clearer and whiter. 

I do this all the time when I need to submit receipts. I would tape the receipts on a wall. Turn the office light on and use Adobe Scan and it works like a charm!