![]() This method however is not really handy.Adobe Acrobat Q1. Higher resolution for the image will improve the quality. One way would be to print the document into an image and let text recognition software recognize it. Your document is an example of such protection. For example letters can be drawn in several overlapping shapes in such way that visually they would still look the same, while text recognition software would fail to recognize text. Some documents can be protected from being converted to text by fooling the Adobe Reader. It works same as if you scanned a paper of printed text and used software like ABBYY FineReader to convert it back to text, but due to infinitely high quality of vector drawings results are typically much better than for scanned documents. However, some PDF readers come with software that allows to analyze the shape and recover the text by using text recognition. In other words instead of reading a letter and drawing it on the screen Adobe Reader as any other PDF reading application would simply draw the vector graphics encoded in the file. PDF documents do not actually contain any letters, but they contain shapes of letters. Services like Evernote might do it on the fly (it does OCR on images I doubt it will do OCR on a PDF). Whatever causes this: if passing through Google Docs or Gmail doesn't work, then maybe the easiest (but far from easy) workaround is indeed to save as TIFF and then do OCR. Maybe Preview has no issues when the exact font happens to be present on the computer itself? Or maybe it's just guessing an encoding, which happens to work for some but not all of the documents? This does not explain why Mac's Preview (and apparently Infix as well) can handle some of the examples when Adobe Reader fails, even with "Encoding: Custom". As far as I can tell it would be very difficult to recover the encoding info. This is a typical example of a PDF that is syntactically fully compliant with the PDF spec but where important information about the meaning of the text in it has been thrown away during the process of making the PDF. The fonts actualy are all embedded, but in a way that all encoding information has been removed. The Phonedisc test fails too, with "Encoding: Custom".Ĭonfusing, and not consistent, but on some Adobe forum I found the following explanation for yet another example that shows "Encoding: Custom" (emphasis mine):Īfter looking inside the PDF it turns out that no usable encoding information is present (neither in the PDF nor in the embedded font data) to derive the meaning of the characters/glyphs that are displayed on the pages in the document. However, both the Leadtek and the Swann examples give problems in Preview on a Mac as well, and in Gmail, and both show "Encoding: Identity-H". Another document shows things like "Encoding: Ansi" or "Roman", and has no issues in neither Preview nor Adobe Reader on a Mac: Its document properties shows "Encoding: Custom" for the fonts. Also, sending it to a Gmail account and then choosing "View" and then "Plain HTML" reveals the text. Note that this would be easier than OCRing a noisy scanned document because the exact shape of the glyph is available (at infinite resolution since it's a "vector" image).įor the TV Manual example: same issue in Adobe Reader 8.1.2 on a Mac, but no problems using Mac's Preview to copy or search text. I guess the ultimate solution in these cases would be to OCR each glyph in a font to figure out what character it really is. Open Office maps some characters into the same Unicode, resulting in apparant letter dropping and doubling. ![]() PDF Type 3 fonts often do not, and TeX DVI has characters that do not have Unicode equivalents. Open-source would be even better.Įdit: The docs for the Multivalent Extract Text tool have a good summary of why things can go wrong, including: (quoted document last modified Jan 2006) I am using Adobe Reader (latest version) for Windows - perhaps an alternative viewer might help? I'm looking for a free solution for Windows. Easterfest 2004 flyer (also from the archive).BAN-TACS Small Business Booklet (archived version).Phonedisc license agreement (from the now-defunct DTMS). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |