https://stackoverflow.com/questions/5472711/dpi-of-image-extracted-from-pdf-with-pdfbox
If it doesn't work, please share your PDF
Tilman
Am 11.04.2018 um 16:17 schrieb Peter Pinnau:
I want to determine if the first page of a document contains a
PDImageXObject which fills the whole page.
I found that piece of code with PDFStreamEngine:
https://www.tutorialkart.com/pdfbox/how-to-get-location-and-size-of-images-in-pdf/
My implementation works so far and finds the PDImageXObject:
if( xobject instanceof PDImageXObject)
{
PDImageXObject image = (PDImageXObject) xobject;
Matrix ctmNew =
getGraphicsState().getCurrentTransformationMatrix();
System.out.println(image.getWidth() + " * " + image.getHeight());
imageDim = new PDRectangle();
imageDim.setLowerLeftX(ctmNew.getTranslateX());
imageDim.setLowerLeftY(ctmNew.getTranslateY());
imageDim.setUpperRightX(ctmNew.getScalingFactorX());
imageDim.setUpperRightY(ctmNew.getScalingFactorY());
}
I want to compare the imageDim with the CropBox of the page. The
CropBox for my A4 test doc is 595.2 x 841.92 as expected.
Since it is a 300dpi scan the pixel size of the image is 2480 * 3508.
My problem is that ctmNew.getScalingFactorX() and
ctmNew.getScalingFactorY() both returns 1.0
How can I find out the display size of the image in user space units
or at least the resolution which the image is rendered within the PDF?
The final goal is a routine which guesses if it is a scanned document
(which my contain text data from OCR) or a pure digital PDF (not
scanned).
Thanks
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