METHOD AND APPARATUS FOR DOCUMENT CONVERSION

• US 20140108897A1
• Filed: 10/16/2012
• Published: 04/17/2014
• Est. Priority Date: 10/16/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: LinkedIn Corporation (Microsoft Corporation)
• Inventors: Boutelle, Jonathan, Gupta, Kapil Mohan, Brown, Michael Casey, Agrawal, Akash, Ahlers, Christopher S., Emmanuel, Jeba Singh, Grover, Ujjwal Singh
• Granted Patent: US 9,471,550 B2
• Time in Patent Office: Days
• US Class Current: 715/201
• CPC Class Codes: G06F 40/109 Font handling; Temporal or kinetic typography
• CPC Class Codes: G06F 40/154 Tree transformation for tree-structured or markup documents, e.g. XSLT, XSL-FO or stylesheets

Abstract

Method and apparatus for converting a document from a fixed-layout format (e.g., Microsoft Office, Adobe PDF) into a non-fixed layout format (e.g., HTML) portable to different platforms (e.g., desktop computers, tablet computer, smart phones) operating different operating systems (e.g., Microsoft Windows, Apple OS X) and different web browsers (e.g., Microsoft Internet Explorer, Apple Safari, Mozilla FireFox). In one stream, fonts are identified, extracted, and processed to enhance compatibility with the portable format. In another stream, textual content is extracted and processed to enhance compatibility and images are taken of non-textual content. These images are used as backgrounds in the output document, over which the textual content is rendered in the appropriate fonts, with sizing, spacing, positioning and/or other characteristics matching or closely approximating that of the original document. Error detection is applied by comparing images of the original document to corresponding images of the output document, to ensure high fidelity.

Claims

1. A method of converting an input document having a fixed-layout into a portable format, the method comprising, for each page of the input document:

extracting a font used on the page;

adjusting metrics of the converted font;

converting the extracted font into a format compatible with a web browser program;

extracting text from the page;

rendering content of the page, other than the font and the text, as one or more content images;

storing the converted font, the extracted text and the one or more content images;

combining the converted font, the extracted text and the one or more content images as a corresponding page of an output document formatted according to a markup language compatible with the web browser program;

comparing an image of the page of the input document to an image of the corresponding page of the output document to generate an error score; and

if the error score exceeds a threshold, replacing the corresponding page of the output document with an image of the page of the input document.

2. The method of claim 1, wherein the markup language is HTML (HyperText Markup Language).

3. The method of claim 1, wherein said extracting a font comprises:

identifying every font used in a first page of the input document; and

identifying every glyph used in every identified font.

4. The method of claim 1, wherein said extracting a font comprises:

extracting a mapping of document-specific character codes used in a first page of the input document to corresponding glyphs; and

replacing the document-specific character codes with Unicode-compatible character codes.

5. The method of claim 4, wherein the Unicode-compatible character codes are UTF-8 (Universal Character Set Transformation Format—

8-bit) code points.

6. The method of claim 1, wherein said extracting a font comprises:

converting a document-specific font file into a format compatible with UTF-8 (Universal Character Set Transformation Format—

8-bit).

7. The method of claim 1, wherein said converting the font comprises replacing the font with one of:

a TrueType font; and

an Embedded OpenType font.

8. The method of claim 7, wherein said converting the font comprises:

converting the font into a scalable vector graphics format prior to said replacing.

9. The method of claim 1, wherein said adjusting metrics of the converted font comprises:

calculating a bounding box for each glyph of each font used in a first page of the input document;

setting an ascent value equal to a sum of a position of a top of the bounding box plus an hhead ascent; and

setting a descent value equal to a sum of a position of a bottom of the bounding box plus an hhead descent.

10. The method of claim 9, wherein said adjusting metrics of the converted font further comprises changing the descent value to a negative number.

11. The method of claim 1, wherein said extracting text from the page comprises:

extracting character codes in the page used to represent text; and

replacing the extracted character codes with Unicode-compatible character codes.

12. The method of claim 1, wherein said extracting text from the page comprises:

extracting multiple blocks of text in the page; and

subdividing a first extracted block of text into multiple sub-blocks of text.

13. The method of claim 12, further comprising:

positioning the multiple sub-blocks of text in the corresponding page of the output document so as to be displayed by the web browser substantially identically to a display of the first extracted block of text in the page of the input document.

14. The method of claim 1, wherein:

said error score measures a percentage of pixels of the image of the corresponding page of the output document that differ from the image of the page of the input document; and

the threshold for the error score is approximately 0.01%.

15. The method of claim 1, wherein said replacing the corresponding page of the output document with an image of the page of the input document comprises:

embedding text of the page of the input document within the output document so as to be searchable by a viewer of the output document.

16. The method of claim 1, further comprising optimizing the output document by:

combining two or more font files assembled from the extracted fonts into a single font file.

17. The method of claim 1, further comprising optimizing the output document by:

replacing one or more background images in the input document with corresponding HTML objects.

18. A computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of converting an input document having a fixed-layout into a portable format, the method comprising, for each page of the input document:

extracting a font used on the page;

adjusting metrics of the converted font;

converting the extracted font into a format compatible with a web browser program;

extracting text from the page;

rendering content of the page, other than the font and the text, as one or more content images;

storing the converted font, the extracted text and the one or more content images;

combining the converted font, the extracted text and the one or more content images as a corresponding page of an output document formatted according to a markup language compatible with the web browser program;

visually comparing an image of the page of the input document to an image of the corresponding page of the output document to generate an error score; and

if the error score exceeds a threshold, replacing the corresponding page of the output document with an image of the page of the input document.

19. An apparatus for converting a fixed-layout input document into a non-fixed format output document, comprising:

a display device for displaying documents;

a processor;

font-processing logic for;

identifying a font used in the input document; and

adjusting the font for use in the output document;

content-processing logic for;

copying textual content of the input document; and

adjusting the textual content;

image logic for;

capturing images of full pages of a document; and

capturing images of non-textual content of pages of the input document; and

error detection logic for;

comparing a page of the output document to a corresponding page of the input document; and

discarding the page of the output document if it differs from the corresponding page of the input document by more than a threshold.