Determining optimal image compression methods for reducing file size

• US 7,130,471 B2
• Filed: 08/22/2005
• Issued: 10/31/2006
• Est. Priority Date: 05/24/2001
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bowler, John, Bossut, Philippe
• Primary Examiner(s): Do, Anh Hong
• Application Number:
  US11/210,228
• Publication Number:
  US 20050280841A1
• Time in Patent Office: 435 Days
• Field of Search: 382/232, 382/239, 382/240, 382/298, 382/299, 382/237, 382/244, 382/166, 369/124.06, 250/208.1, 348/97, 358/3.07, 358/3.27, 358/474, 358/1.15, 707/104.1
• US Class Current: 382/232
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00

Abstract

The present invention operates as an expert system to automatically determine an optimal method for reducing the size of an electronic file containing at least one embedded image by determining optimal methods for compressing each image. Further, in one embodiment, linked images are also compressed. User control of relevant parameters such as image compression options, retention or removal of unnecessary data associated with embedded or linked images, and downsampling images to better match the output resolution of specific output devices is provided in further embodiments. Further, to prevent cumulative degradation of images through repeated lossy compression, images that have already been compressed or optimized are preferably flagged so that they are not compressed more than once.

Claims

1. A method for automatically determining an optimal method for reducing the size of an electronic file having at least one image, comprising using a computing device to perform the following steps:

automatically determining characteristics of each image;

determining resolution characteristics of an output destination of the electronic file;

automatically setting a resolution of each image based on the output destination of the electronic file; and

automatically determining an optimal compression method for each image based on the image characteristics.

2. The method of claim 1 further comprising steps for applying the optimal compression method to each image for reducing the size of the electronic file.

3. The method of claim 2 further comprising steps for applying the optimal compression method to each image as each image is embedded in the electronic file.

4. The method of claim 2 further comprising steps for applying the optimal compression method to each image as the electronic file is saved.

5. The method of claim 2 further comprising steps for applying the optimal compression method to each image in response to a request to optimize the images made via a user interface.

6. The method of claim 1 further comprising steps for automatically discarding OLE data associated with each image.

7. The method of claim 1 further comprising steps for automatically discarding cropped portions of each image in the electronic file.

8. The method of claim 1 further comprising steps for automatically discarding color information for each image in the electronic file where the output device is a grayscale output device.

9. A system for automatically reducing the size of an electronic file having at least one associated image, comprising using a computing device for:

determining characteristics of each associated image;

discarding unnecessary data associated with each associated image;

determining an optimal compression method for each associated image based on the characteristics of each associated image; and

applying the optimal compression method to each associated image.

10. The system of claim 9 further comprising determining an intended output device for the electronic file and automatically downsampling each associated image to match a resolution of the intended output device.

11. The system of claim 9 wherein the unnecessary data is any of:

OLE data coupled to each associated image;

non-displayed cropped portions of each associated image;

color information for each associated image; and

any data not necessary for rendering the image.

12. The computer-implemented process of claim 9 wherein a color bit depth of any associated image is automatically reduced when it is determined that a lower image bit depth will result in a visually identical image.

13. A computer-implemented process for automatically reducing the size of an electronic file having at least one embedded image, comprising steps for:

determining characteristics of each embedded image;

determining an output destination of the electronic file;

automatically setting a resolution of each image based on the output destination of the electronic file;

discarding unnecessary data associated with each embedded image;

determining an optimal compression method for each associated image based on the characteristics of each embedded image; and

applying the optimal compression method to each embedded image for reducing the size of the electronic file.

14. The computer-implemented process of claim 13 wherein the electronic file has at least one linked image, and further comprising steps for treating each linked image in the same manner as each embedded image.

15. The computer-implemented process of claim 13 wherein the unnecessary data includes any of:

OLE data coupled to each embedded image, and wherein the OLE data is associated with at least one predefined application program;

non-displayed cropped portions of each embedded image;

color information for each embedded image; and

any other data not necessary for rendering the image.

16. The computer-implemented process of claim 13 further comprising steps for automatically resampling any embedded image that has been reduced in size relative to an original size for that image.

17. The computer-implemented process of claim 13 further comprising steps for instantiating a user interface for interacting with the computer-implemented process.

18. The computer-implemented process of claim 13 wherein the optimal compression method includes any of lossless and lossy compression methods, and further comprising steps for automatically applying the lossless compression method to each embedded image for which the optimal compression method is the lossless compression method.

19. The computer-implemented process of claim 18 further comprising steps for automatically applying the lossy compression method to each associated image for which the optimal compression method is the lossy compression method.

20. The computer-implemented process of claim 18 further comprising steps for automatically applying the lossy compression method to each image for which the optimal compression method is the lossy compression method when a calculated amount of loss is below a predetermined loss threshold.