OCR uploaded PDF's when they only contain the image of a receipt and not text

For the app to OCR uploaded image pdf's instead of using the camera.

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If you upload a PDF that only contains an image of a receipt - if will not be scanned. This is the case with output of many mobile scanner apps. If the PDF has "normal" text, then it is scanned. This needs to be detected somehow in the app, and the page sent to image OCR instead of a PDF reader.