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Is there a way to detect page rotation
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Stefan  
#1 Posted : Monday, April 4, 2016 9:23:07 AM(UTC)
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Stefan

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Joined: 4/4/2016(UTC)
Posts: 4
Germany
Location: Munic
Hey,
I am currently searching for an alternative for our current rasterizing SDK and found Pdfium. I was wondering, if there is an automated way to detect the rotation of a pdf file?
Lets say I have a document that is scanned upide down and sent to Pdfium as PDF file. Is it possible to detect the rotation of the content?

EDIT:
Is it possible to output a deskewed and correctly oriented version of the page, maybe in combination with your tesseract SDK? I know that tesseract has OSD, so can you tell the renderer to rotate the output pdf accordingly?

Edited by user Tuesday, April 5, 2016 4:55:45 AM(UTC)  | Reason: Not specified
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Guest  
#2 Posted : Tuesday, April 5, 2016 6:47:30 AM(UTC)
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Guest

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well ... you can try to recognize the image four times at different angles, and choose the one of them where the most good result. To evaluate the result you can use the TextConfidences property.

Edited by user Tuesday, April 5, 2016 6:55:59 AM(UTC)  | Reason: Not specified
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Paul Rayman  
#3 Posted : Tuesday, April 5, 2016 10:20:53 PM(UTC)
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Paul Rayman

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There is a another way to determine the page orientation.
The following code works perfect for me.
Please make sure that you have the osd.traindata data file in your output tessdata folder.

Code:

var api = OcrApi.Create();

api.Init();
api.PageSegmentationMode = Patagames.Ocr.Enums.PageSegMode.PSM_AUTO_OSD;
api.SetImage(bmp);
api.Recognize();

var iterator = api.AnalyseLayout();
var orientation = iterator.Orientations;
switch(iterator.Orientations)
{
	case Patagames.Ocr.Enums.Orientation.ORIENTATION_PAGE_DOWN:
		//the image is rotated to 180 
		break;
	case Patagames.Ocr.Enums.Orientation.ORIENTATION_PAGE_LEFT:
		//the image is rotated to 270 clockwise
		break;
	case Patagames.Ocr.Enums.Orientation.ORIENTATION_PAGE_RIGHT:
		//the image is rotated to 90 clockwise
		break;
	case Patagames.Ocr.Enums.Orientation.ORIENTATION_PAGE_UP:
		//the image is rotated to 0
		break;
}
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Is there a way to detect page rotation (F.A.Q.)
by Paul Rayman 10/14/2016 6:34:54 PM(UTC)
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