Compressing images in documents

• US 20070140559A1
• Filed: 12/15/2005
• Published: 06/21/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Jaremko, Mark, Hill, Ryan, Moldovan, Bogdan, Rambharack, Jeffrey
• Granted Patent: US 7,978,922 B2
• Time in Patent Office: Days
• US Class Current: 382/171
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

Images that are contained within documents are compressed to reduce the file size of the document. The compression may occur such that compression steps occur to the image automatically. The compression steps performed are determined based on the information available about the images in a document. The information is used to determine whether or not the image should be compressed as well as what compression method is used.

Claims

1. A computer-implemented method for compressing images stored in a document, comprising:

accessing an image within the document;

wherein the document includes other data in addition to the image;

classifying the image;

automatically determining the compression steps for the image;

applying the compression steps to the image; and

saving the document with the compressed image.

2. The computer-implemented method of claim 1, wherein classifying the image comprises classifying the image as at least one of:

a photograph and a non-photograph.

3. The computer-implemented method of claim 1, further comprising determining when an image is inserted into the document and when the image is inserted automatically performing at least one of the following operations:

stripping unnecessary data from the image;

resampling the image; and

converting the image to another format.

4. The computer-implemented method of claim 3, further comprising determining when an image is saved and when the image is saved performing at least one of the following operations:

discarding a cropped region of the image; and

resampling the image based on a placed size.

5. The computer-implemented method of claim 2, wherein classifying the image comprises building a histogram of the image.

6. The computer-implemented method of claim 2, wherein automatically determining the compression steps for the image comprises determining at least one of:

whether the image may be palletized;

whether the image is a wrong format;

whether there are unneeded pixels;

whether the image includes transparency information;

whether the image has been cropped; and

whether the image has been resized.

7. The computer-implemented method of claim 6, wherein determining whether the image has been cropped comprises determining cropped regions and discarding the cropped regions.

8. The computer-implemented method of claim 6, wherein determining whether the image has been resized comprises resampling the image.

9. The computer-implemented method of claim 6, wherein determining whether the image has unneeded pixels comprises determining a desired resolution and resampling the image based on the desired resolution.

10. A computer-readable medium having computer-executable instructions for automatically compressing images stored in a document, comprising:

accessing an image within the document;

classifying the image;

automatically determining the compression steps for the image;

automatically applying the compression steps to the image; and

saving the document with the compressed image such that a file size of the document is reduced.

11. The computer-readable medium of claim 10, further comprising determining when an image is inserted into the document and when the image is inserted automatically performing removing unnecessary data from the image when determined;

resampling the image when determined; and

converting the image to a JPEG format when determined.

12. The computer-readable medium of claim 11, further comprising determining when an image is saved and automatically compressing the image in response to the save.

13. The computer-readable medium of claim 10, wherein classifying the image comprises building a histogram of the image and using the histogram to determine whether the image is a photograph.

14. The computer-readable medium of claim 13, wherein determining whether the image is a photograph comprises performing at least one of the following tests based on the histogram:

determining a fraction of pixels in top bins of the histogram;

determining a number of histogram spikes; and

determining a number of loaded bins.

15. The computer-readable medium of claim 10, wherein automatically determining the compression steps for the image comprises performing at least two of:

determining whether the image may be palletized;

determining whether the image is a wrong format;

determining whether there are unneeded pixels and when there are unneed pixels resampling the image;

determining whether the image includes transparency information;

determining whether the image has been cropped and when the image has been cropped removing cropped regions; and

determining whether the image has been resized and when the image has bee resized resampling the image.

16. A system for compressing images stored in a document, comprising:

an input device that is configured to receive input;

a document that includes an image;

an application configured to edit the document and that is configured to receive the input from the input device; and

a compression algorithm that is coupled to the application and that is configured to automatically compress the image when determined;

wherein the algorithm is configured to perform actions, comprising;

accessing the image within the document;

classifying the image as one of;

a photograph and a non-photograph;

automatically determining the compression steps for the image;

applying the compression steps to the image; and

saving the document with the compressed image.

17. The system of claim 16, further comprising determining when an image is inserted into the document and when the document is saved.

18. The system of claim 17, wherein determining when the image is inserted into the document and when the document is saved comprises automatically performing at least one of the following operations:

stripping unnecessary data from the image;

resampling the image;

converting the image to another format;

discarding a cropped region of the image; and

resampling the image based on a placed size.

19. The system of claim 18, wherein classifying the image comprises building a histogram of the image and analyzing the histogram to determine pixel disbursement.

20. The system of claim 18, wherein automatically determining the compression steps for the image comprises determining at least one of:

whether the image may be palletized;

whether the image is a wrong format;

whether there are unneeded pixels;

whether the image includes transparency information;

whether the image has been cropped; and

whether the image has been resized.