Image bounds displaced from real position

[frojasg1]

Hello,

The previous request was because I wanted to use that ami3 function, because mine (based also on the one of ami3) with some books adds an offset to position of images.
But I have checked, linking from my library to ami3 and using ami3 getBoundingRect().
That function gives also the displaced location on images of some books.

You can check with that pdf example:
https://www.frojasg1.com/Test-1.pdf

It gives an offset to the position of the image at the bottom.

[frojasg1]

I have found the issue with my code (may be ami3 is not supposed to take those displacements into account, I do not know).

Any way, I place here the code to extract the image bounds placed on the page image at 72dpi, with all transformations done: (my code, only deals with Rectangle, instead of with SVGRect)

public class MyPDFRenderer extends PDFRenderer
{
	protected List<GlyphWrapper> _listOfGlyphs = new ArrayList<>();
	protected List<ImageWrapper> _listOfImages = new ArrayList<>();

	private AffineTransform flipAT;
	private AffineTransform rotateAT;
	private AffineTransform transAT;

	...

		// copied from DrawPrintTextLocations.java pdfbox example
		protected void createTransformations()
		{
			PDPage pdPage = getCurrentPage();
			PDRectangle cropBox = pdPage.getCropBox();

			flipAT = new AffineTransform();
			flipAT.translate(0, pdPage.getBBox().getHeight());
			flipAT.scale(1, -1);

			// pageIndex may be rotated
			rotateAT = new AffineTransform();
			int rotation = pdPage.getRotation();
			if (rotation != 0)
			{
				PDRectangle mediaBox = pdPage.getMediaBox();
				switch (rotation)
				{
					case 90:
						rotateAT.translate(mediaBox.getHeight(), 0);
						break;
					case 270:
						rotateAT.translate(0, mediaBox.getWidth());
						break;
					case 180:
						rotateAT.translate(mediaBox.getWidth(), mediaBox.getHeight());
						break;
					default:
						break;
				}
				rotateAT.rotate(Math.toRadians(rotation));
			}

			// cropbox
			transAT = AffineTransform.getTranslateInstance(-cropBox.getLowerLeftX(), cropBox.getLowerLeftY());
		}

		private Rectangle getBoundingRect() {

			Matrix ctm = getGraphicsState().getCurrentTransformationMatrix();
			AffineTransform at = ctm.createAffineTransform();
			Shape bbox = new Rectangle2D.Float(0, 0, 1, 1);
			bbox = at.createTransformedShape(bbox);

			bbox = flipAT.createTransformedShape(bbox);
			bbox = rotateAT.createTransformedShape(bbox);
			bbox = transAT.createTransformedShape(bbox);

			Rectangle result = bbox.getBounds();

			return( result );
		}

		protected ImageWrapper createImageWrapper( PDImage pdImage )
		{
			ImageWrapper result = null;
			RenderedImage image = ExecutionFunctions.instance().safeFunctionExecution( () -> pdImage.getImage() );
			if( image != null )
			{
				createTransformations();
				Rectangle rect = getBoundingRect();
				result = new ImageImpl( image, rect );
			}

			return( result );
		}


		@Override
		public void drawImage(PDImage pdImage) throws IOException {
			super.drawImage(pdImage);

			ImageWrapper image = createImageWrapper( pdImage );
			if( image != null )
				_listOfImages.add( image );
		}

	...
}

Sorry for so many messages.

[petermr]

I am afraid I don't understand the issue. I am unclear what is wrong , if anything. I suggest you create a failing test showing the expected and actual values.

…

On Thu, May 7, 2020 at 2:57 PM frojasg1 ***@***.***> wrote: I have found the issue with my code (may be ami3 is not supposed to take those displacements into account, I do not know). Any way, I place here the code to extract the image bounds placed on the page image at 72dpi, with all transformations done: (my code, only deals with Rectangle, instead of with SVGRect) public class MyPDFRenderer extends PDFRenderer { protected List<GlyphWrapper> _listOfGlyphs = new ArrayList<>(); protected List<ImageWrapper> _listOfImages = new ArrayList<>(); private AffineTransform flipAT; private AffineTransform rotateAT; private AffineTransform transAT; ... // copied from DrawPrintTextLocations.java pdfbox example protected void createTransformations() { PDPage pdPage = getCurrentPage(); PDRectangle cropBox = pdPage.getCropBox(); flipAT = new AffineTransform(); flipAT.translate(0, pdPage.getBBox().getHeight()); flipAT.scale(1, -1); // pageIndex may be rotated rotateAT = new AffineTransform(); int rotation = pdPage.getRotation(); if (rotation != 0) { PDRectangle mediaBox = pdPage.getMediaBox(); switch (rotation) { case 90: rotateAT.translate(mediaBox.getHeight(), 0); break; case 270: rotateAT.translate(0, mediaBox.getWidth()); break; case 180: rotateAT.translate(mediaBox.getWidth(), mediaBox.getHeight()); break; default: break; } rotateAT.rotate(Math.toRadians(rotation)); } // cropbox transAT = AffineTransform.getTranslateInstance(-cropBox.getLowerLeftX(), cropBox.getLowerLeftY()); } private Rectangle getBoundingRect() { Matrix ctm = getGraphicsState().getCurrentTransformationMatrix(); AffineTransform at = ctm.createAffineTransform(); Shape bbox = new Rectangle2D.Float(0, 0, 1, 1); bbox = at.createTransformedShape(bbox); bbox = flipAT.createTransformedShape(bbox); bbox = rotateAT.createTransformedShape(bbox); bbox = transAT.createTransformedShape(bbox); Rectangle result = bbox.getBounds(); return( result ); } protected ImageWrapper createImageWrapper( PDImage pdImage ) { ImageWrapper result = null; RenderedImage image = ExecutionFunctions.instance().safeFunctionExecution( () -> pdImage.getImage() ); if( image != null ) { createTransformations(); Rectangle rect = getBoundingRect(); result = new ImageImpl( image, rect ); } return( result ); } @OverRide public void drawImage(PDImage pdImage) throws IOException { super.drawImage(pdImage); ImageWrapper image = createImageWrapper( pdImage ); if( image != null ) _listOfImages.add( image ); } ... } Sorry for so many messages. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#39 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFTCS5P4X5HOONIBDMUXCTRQK44XANCNFSM4M3KBFGA> .

-- Peter Murray-Rust Founder ContentMine.org and Reader Emeritus in Molecular Informatics Dept. Of Chemistry, University of Cambridge, CB2 1EW, UK

[frojasg1]

Well, I am not an expert on your ami3 tool.
What I can do, is to show you the difference between the image positions extracted before and after the correction, with a suitable PDF for the test.
In the application before the correction, image positions were extracted in the same way as ami3 does.
In the application after the correction Image positions are extracted with the function I pasted in my previous comment.

You can download the two versions of the application here:

• before correction: https://www.frojasg1.com:8443/downloads_web/downloadServletv3?file=pdfInspector.v1.0_20200505&language=English
• after correction: https://www.frojasg1.com:8443/downloads_web/downloadServletv3?file=pdfInspector.v1.0&language=English

You can find the pdf for testing here:
https://www.frojasg1.com/Test-1.pdf

Start the two versions of the application, open the pdf for testing and place mouse cursor over the image on the bottom.
A blue frame with the boundaries of the image will be shown.
Notice the difference between the frame showed with the two versions.

I think it must have to do with:

	PDPage pdPage = getCurrentPage();
	PDRectangle cropBox = pdPage.getCropBox();
	transAT = AffineTransform.getTranslateInstance(-cropBox.getLowerLeftX(), cropBox.getLowerLeftY());
	bbox = transAT.createTransformedShape(bbox);

Which may be is not taken into account with the previous way (copied from ami3) to calculate those bounds.

But as I said in a previous comment, I do not know if ami3 is supposed to have into account those details, or if its output is accurate enough for the purpose it is intended to.