Compressing images in documents

• US 7,978,922 B2
• Filed: 12/15/2005
• Issued: 07/12/2011
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hill, Ryan C., Jaremko, Mark, Moldovan, Bogdan R., Rambharack, Jeffrey R.
• Primary Examiner(s): Ge; Yuzhen
• Application Number:
  US11/303,153
• Publication Number:
  US 20070140559A1
• Time in Patent Office: 2,035 Days
• Field of Search: None
• US Class Current: 382/239
• 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:

utilizing a processor on a computing device, accessing an image within the document;

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

determining from the document whether an automatic compression feature is turned on;

classifying the image;

automatically determining a plurality of compression steps for the image to be applied at a first time;

automatically applying the plurality of compression steps to the image at the first time;

determining that the compressed image is manipulated after the plurality of compression steps are applied to the image at the first time by a user performing a resize operation such that the compressed image is resized;

setting a flag indicating that the compressed image has been modified; and

in response to saving the document checking the flag and performing an additional compression step of resampling the compressed image at a second time according to a new size of the resized compressed image when the flag indicates that the compressed image has been modified.

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 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 when the document is saved discarding a cropped region of the compressed image.

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 storage memory storing computer-executable instructions for automatically compressing images stored in a document, the computer-executable instructions causing a computer to execute a method comprising:

determining from the document whether an automatic compression feature is turned on;

accessing an image within the document;

classifying the image;

automatically determining a first set of compression steps for the image;

automatically applying the first set of compression steps to the image at a first time;

setting a flag indicating that the image has been modified; and

in response to saving the document and determining that the flag indicates that the compressed image has been modified automatically applying a second set of compression steps to the compressed image at a second time.

11. The computer-readable storage memory 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;

resampling the image; and

converting the image to a JPEG format.

12. The computer-readable storage memory of claim 11, further comprising determining when a document is saved and automatically discarding a cropped region of the compressed image.

13. The computer-readable storage memory 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 storage memory 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 storage memory of claim 10, wherein automatically determining the first set of compression steps and the second set of 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 unneeded 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:

a processor and a computer-readable storage medium;

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 performs operations relating to the application and that is configured to automatically compress the image when determined;

wherein the algorithm is configured to perform actions using the processor, comprising;

determining from the document whether an automatic compression feature is turned on;

accessing the image within the document;

classifying the image as one of;

a photograph and a non-photograph;

automatically determining a first set of compression steps for the image;

applying the first set of compression steps to the image at a first time before a save of the document;

setting a flag indicating that the image has been modified; and

in response to saving the document determining when the flag indicates that the compressed image has been modified and automatically applying a second set of compression steps to the compressed image at a second time.

17. The system of claim 16, wherein automatically compressing the image when determined comprises determining whether an image is inserted into the document.

18. The system of claim 17, wherein determining whether the image is inserted into the document 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 first set of compression steps for the image comprises determining:

whether the image may be palletized;

whether the image is a wrong format;

whether there are unneeded pixels; and

whether the image includes transparency information.