Hi,
The dpi information embedded in the image is 300 for EzFQJ9v.png but on
US08000000-20110816-D00001.png it is 72.
I extracted the image of the head only from both the pngs and get two
different pixel size:
the head in EzFQJ9v.png is 1722x1593, the head in
US08000000-20110816-D00001.png is 1331x1231.
I would say that Google has a resized image and changed the dpi info to 72.
The image info for the pdf page is:
position in PDF = -1.2, 0.0 in user space units
raw image size = 2560, 3300 in pixels
displayed size = 614.4, 792.0 in user space units
displayed size = 8.533334, 11.0 in inches
displayed size = 216.74667, 279.4 in millimeters
dpi = 300 dpi (X), 300 dpi (Y)
/Toël
On 11 mar 2016, at 09:14, Vince Harron <[email protected]> wrote:
Here is the original patent from the US Patent and Trademark Office:
http://pimg-fpiw.uspto.gov/fdd/00/000/080/0.pdf
I'm extracting images as follows:
List<PDPage> list = document.getDocumentCatalog().getAllPages();
String fileName = srcPdfFile.getName().replace(".pdf", "_cover");
int imageNumber = 0;
for (PDPage page : list) {
PDResources pdResources = page.getResources();
Map pageImages = pdResources.getImages();
if (pageImages != null) {
Iterator imageIter = pageImages.keySet().iterator();
while (imageIter.hasNext()) {
String key = (String) imageIter.next();
PDXObjectImage pdxObjectImage = (PDXObjectImage)
pageImages.get(key);
pdxObjectImage.write2file(srcPdfFile.getAbsolutePath().replace(".pdf",
String.format("-D%05d.png", imageNumber)));
imageNumber++;
}
}
}
The image I extract from page 2 looks like this:
http://i.imgur.com/EzFQJ9v.png
2560x3300 (300dpi)
Here is the same image from Google Patents
https://patentimages.storage.googleapis.com/US8000000B2/US08000000-20110816-D00001.png
it's only 1446 × 2037 (~224dpi)
The Google image is cropped a bit compared to the PDF page. When I trim
the my PDF page image down to match the same area as the Google image,
the
my extracted image is still much higher resolution than the Google
extracted image (1934 × 2550)
Assumption 1) Google is using the same data source as me (PDF)
Assumption 2) Google wouldn't downscale technical diagrams in patents
because they might lose important detail
If my assumptions are correct, I must be extracting the image
incorrectly,
upsampling the ~224dpi image to 300dpi. Is that what's happening?
Thanks,
Vince
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