I have a document that was created from a scanned document, after using the Acrobat XI pro's text recognition tool, with parameters language: Spanish; PDF output: clear scan; downsample to 600 dpi.
It worked rather well, with only small problems, which can be easily overlooked. Except that I use foxit PDF reader to actually read PDF (I have a slow PC), and there is an "a" glyph that in Adobe looks normal, but in foxit it looks filled, without the empty space at its center (the problem exists only in italics lowercase "a")
(example of problem). There are lots of lower case italics a's, almost in every other page. I use this book to study for a central course for my degree, it's the best we have at our school's library in Spanish, so I read it almost every day, and it's quite annoying (example 2).
There are examples of that italics lowercase "a" that show up fine in foxit the a's in "plantación" are normal.
Sample pages, the first page has normal a's, the second has filled a's
Could I copy the normal looking a glyph and replace the one that causes the problem? if so, what software would I need?
Thanks for reading this.
Yes it is possible to change the ClearScanType (Fd1428390-Identity-H) to conventional font here changed to 11pt Times Roman Italic. Also messed with colour, size and bold to demonstrate effects, but you just need to use one combination.
This change is allowed in the Free version of Tracker PDF-XChange Editor but beware if not done cautiously text edits could trigger demo watermarks.
Select the edit text only from buttons then select text, with properties pane active (on the right) and make changes, if you see the demo banner appear then Ctrl-Z and try a different approach.
Related
I have this PDF ebook with selectable text - the handwriting - but there is no such font embedded and the letters are all different, so it's not actually a font. How is this possible?
I've worked with CorelDraw and Adobe Acrobat, but I can't understand how this works.
The left side of the picture shows the document properties, the right side shows a page of the PDF file and I selected the last 3 rows. I can copy and paste that to a text file, no problem. How was this achieved?
There are a few possibilities but the most likely is the text is being converted to outlines/paths or vectors. Some software such as Adobe InDesign and other print design apps allow you to 'flatten' a font based text into vector or paths, meaning the original font isn't required to be embedded or installed on the system. The original text data is however still present and able to be copied into a text field or word processor.
this is the first I'm working with PDFs on this level. So please be patient with
my noob question. I understand the logical and physical structure of an PDF file
on a basic level.
I have an PDF that contains a dummy ID that needs to be replaced. To check, if there
is way to do this, I used qpdf to expand the PDF using
qpdf --qdf --object-streams=disable orig.pdf expanded.pdf
Using a hex editor I located the dummy ID in expanded.pdf and changed the value by
simply swapping two digits
<001800180017> Tj => <001700170018> Tj
and saved it. Opening expanded.pdf in Acrobat didn't show the modification. The original
ID 443 is still rendered, but searching for "443" doesn't find it. When searching for
"334", the modified content, I get the rendered original ID 443 highlighted.
The PDF consist of text and vector graphic. When I insert additional digits (which obviously
invalidates the offsets in the xref), I get an error message regarding a missing font and
all digits are shown as dots but the vector graphic is still in place. This seems to indicate
that the ID is not part of the graphic.
What did I miss?
EDIT 1:
After mkl's comment, I did a deeper analysis of my PDF and found, that beside the obvious graphic content, all text was rendered by a series of m/l/c commands follwoed by a BT/ET section. Color for stroke and non-stroke was 0,0,0 for both in the BT/ET section.
Is this because of the used embedded non-standard font?
Are PDFs with embedded fonts usually done this way? A graphics part for the visual representation and a transparent (hidden) text part just to get searching and highlighting capabilities?
Looking back I wonder what I did to get the dots when I first modified the
content. I seems impossible and I can't reproduce it either.
Thanks
Tom
First off, the following is merely guesswork as you could not share the pdf in question. Educated guesswork but guesswork nonetheless.
You report that you changed the value by simply swapping two digits in the text drawing instruction argument and now can successfully search for the value with swapped digits but that Acrobat didn't show the modification.
Furthermore you observed that all text was rendered by a series of m/l/c commands followed by a BT/ET section.
The main situation in which one observes text being rendered as arbitrary vector graphics (a series of m/l/c commands), is in pdfs in which the producer didn't want text extraction to be possible and replaced text drawing instructions by arbitrary vector graphics instructions.
This apparently is not the case in your pdf as the text drawing instructions are not replaced but merely supplemented by the vector graphics ones.
Supposing that this construct is used for a reason and not by accident, I can only assume that the pdf producer was not willing or allowed to embed the font in question but wanted the specific font appearance to be displayed without having to count on the font being installed on the computer the pdf is viewed on.
Thus, the text appearance is drawn using arbitrary vector graphics instructions and the following text drawing instructions actually draw nothing but merely make the text searchable and extractable. This way there is no need to embed the apparent font face as font program. (Text drawing instructions can be made to draw nothing either by using a font with all blank glyphs or by using the text rendering mode "invisible".)
If this assumption turns out to be correct, your task to replace the dummy id requires not merely editing the arguments of the text drawing instructions but also replacing the arbitrary vector graphics instructions showing the dummy id appearance by other instructions showing the actual id.
If you happen to have the font in question and are willing and able to embed it, you can actually replace the arbitrary vector graphics instructions by text drawing instructions using the font. Otherwise be prepared to also draw the actual id as arbitrary vector graphics.
// EDIT 26.03.2018 - Who wants to continue my work can have a look on my source-files https://github.com/n0l0cale/ocr-sampledata
I'm actually looking for some details about PDF Files. It's most important for me that the files will be usable for a very long time and if possible the OCR should be automatically applied for new files (which seems to be not really possible with Adobe Acrobat...).
For that I've been looking for different solutions how to OCR my PDF Files. I found three candidates which seems to be doing what they should do... (more or less). But all three variants have their pro&cons... But there seem to be different approaches how to store data in PDF Files.... for all three Variants... Let me explain:
a File OCRed with Adobe Acrobat:
https://github.com/n0l0cale/ocr-sampledata/blob/master/A4%20sample_ACROBAT.pdf
results in a file that Acrobat is able to open in one step (no preloading of any background layer) and after a preflight-script I'm able to see the text which is stored hidden:
a File OCRed with Abby Finereader:
https://github.com/n0l0cale/ocr-sampledata/blob/master/A4%20sample_ABBY.pdf
does not seem suitable for the default adobe preflight-script as it does not display any additional layers:
But far as I was able to reproduce these Files seems to have a Background-Text-Layer, which contains the OCRed Text, which is the underlying layer for the Image that is shown to the user at the end. Unfortunately this seems to be loaded separately and this is confusing while opening the file with Adobe Acrobat...
a File OCRed with Tesseract 4 (Alpha):
https://github.com/n0l0cale/ocr-sampledata/blob/master/A4%20sample_TESSERACT_oem2.pdf
is also doing some weird magic with the hidden text part:
But in all three cases I'm able to search for words in the files and see the text using "Remove hidden information" and selecting "hidden text":
I'm seriously confused.... Does anyone know how these programs are storing their hidden text information really?
S.
P.S.: For those wondering what this ominous preflight script is: https://theblog.adobe.com/hidden-gems-in-acrobat-dc-how-to-optimize-hidden-ocr-text/
Does anyone know how these programs are storing their hidden text information really?
You correctly have found out that the approach of Abby Finereader is different from that of Adobe Acrobat and of Tesseract:
Abby creates a page content stream in which first the text is drawn normally on the page and eventually covered by the scanned image.
Acrobat and Tesseract create content streams in which first the image is drawn and then the text is drawn invisibly (using text rendering mode 3 which draws nothing).
The difference between the latter two results is the choice of font used:
Acrobat uses regular standard 14 fonts for which a PDF viewer has a font program to render them as normal glyphs.
Tesseract uses a font GlyphLessFont it embeds a font program for into the result file. When rendered the glyphs in this font do not show as our normal Latin glyphs but merely as empty space.
Considering the visual effect you observed for the Abby result, the approach used by Acrobat or Tesseract might be preferable.
Whether one prefers fonts with visually recognizable glyphs (as used by Acrobat) or without (as used by Tesseract), is mostly a mere matter of taste. They are used only in the invisible rendering mode anyways.
I'm working on a project that involves the Fannie Mae/Freddie Mac Uniform Appraisal Dataset. The specification requires that the embedded appraisal PDF file be first-generation.
I understand conceptually what a first-generation PDF file is (printing of a document directly to PDF, rather than a scanned copy or printed and scanned copy). However, I've done some research and haven't found anything that specifies the properties of a first-generation PDF that could be verified programmatically.
I found a product that allows one to check if a PDF contains text, images, or both: Apose.Pdf.Kit for .NET, but I'm looking for a way to program this myself, for budgetary and other reasons. Also, I'm not sure that determining that the file contains text will be sufficient to verify that it's first-generation.
Given that this is an industry requirement of a very large industry, I feel like someone must have already tackled this issue, but I'm having a hard time finding anything.
Thanks in advance for any help.
There is no way to know for certain if a PDF is "first generation". Technically, a scanned PDF is just a PDF that contains images and perhaps OCR'ed text on top of that. A "first generation" PDF could easily have the same characteristics, so you have to use some heuristics.
For example, a PDF that contains only images and invisible text (from OCR) is likely to be scanned, a PDF that has visible text or vector graphics is probably "first generation" (OCR for scanned PDFs works by overlaying invisible text on top of the original image, so that text selection works, but the original document's fidelity is preserved).
Open pdf, ctrl "f" type in Appraisal. If you have a hit for the word, you have a first generation apprsl. Rather, the dataset exist.
Well basically I'm finishing school in mid December so I'm just brushing up my resume and I'm wondering if there's a way to use custom fonts (in this case Calibri and Cambria) in a PDF file and make them render correctly on all computers.
Thanks in advance!
EDIT: I'm using MS Word 2007, but am open to suggestions
PDFs don't store text and fonts like other documents, they actually convert the font to vectors, that way no matter what font you use, the document displays exactly as expected. This is why searching for text inside the PDF is such a problem for 3rd party PDF Readers and why even Adobe themselves use to distribute 2 versions of Acrobat (one with text search, one without).
Another thing to keep in mind is, PDF isn't pixel exact, it's ratio exact. PDF readers generally do not use a 100% zoom level, instead most people read them at "fit to screen" or "fit to page". I point this out because I'm guessing the reason you are trying to use those new Vista/Office 2007 fonts is because of their LCD subpixel support (improves readability on LCD screens). This feature will not translate into the PDF, since the letter becomes a vector, subpixel information is lost, and even if it wasn't, becomes useless because the vector will be sized to something other than you intended at view time.
The PDF format is capable of embedding fonts, if the font has been marked embeddable by its creator. You'll have to check the software that's creating your PDF to see if it has the capability and how to enable it.
theoretically speaking, on technical side, embedding/not embedding ability, regarding the fonts, is settled with a special flag in font file (ttf or opentype or type1)
you can view this special embedding flag with any font editor program (I recommend
FontCreator (by High-logic)
http://www.high-logic.com/font-editor/fontcreator.html
with a free trial fully operative and without limitations
you can also change embedding/not embedding flag, but legally speaking, for the 99% of fonts commercially distributed, this breaks the license of font