BURST MODE IMAGE COMPRESSION AND DECOMPRESSION

• US 20120106852A1
• Filed: 10/28/2010
• Published: 05/03/2012
• Est. Priority Date: 10/28/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Khawand, Charbel, Mikolajczyk, Peter
• Granted Patent: US 8,655,085 B2
• Time in Patent Office: Days
• US Class Current: 382/218
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/619 the transform being operated outside the prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

Modified compression/decompression and metadata in burst mode images reduce the storage space consumed by burst mode images. Metadata is added to image files (e.g., EXIF files) to establish links between images in a burst mode image series. A series of linked burst mode images can include delta images representing a temporal difference between the image data (e.g., pixel data) for two burst images captured at different time instances. Difference information can be compressed. A root image for a linked burst mode series can be identified and used as a reference for other burst images. Metadata can be added to image files to link burst images prior to compression, after compression, or at an intermediate stage of compression of image data. Difference information for delta image files can be derived prior to compression, after compression, or at an intermediate stage of compression of image data.

Claims

1. A computer-implemented method comprising:

obtaining image data for plural images in a burst mode image series;

calculating a difference between image data for a first image of the plural images in the burst mode image series and image data for a second image of the plural images in the burst mode image series; and

storing delta image metadata and information representing the difference as an image file, wherein a set of one or more image metadata linker fields link the second image to the first image to facilitate reconstruction of the second image based on the information representing the difference and the image data for the first image.

2. The method of claim 1 further comprising:

reconstructing the first image using information representing the image data for the first image; and

reconstructing the second image based on the set of one or more image metadata linker fields, the information representing the difference, and the image data for the first image, wherein the set of one or more image metadata linker fields comprises;

a root image identifier field; and

an image index field comprising an index value representing an index in the burst mode image series for the second image relative to the first image.

3. The method of claim 1 wherein the image file with the delta image metadata is a delta image file, the method further comprising:

storing root image metadata and information representing the image data for the first image as a root image file separate from the delta image file.

4. The method of claim 3 wherein the root image file and the delta image file are EXIF files, wherein the information representing the difference is a compressed version of the difference, and wherein the information representing the image data for the first image is a compressed version of the image data for the first image.

5. The method of claim 3 wherein the root image metadata comprises a second set of one or more image metadata linker fields comprising:

a root image identifier field;

an image index field comprising an index value representing an index in the burst mode image series for the first image.

6. The method of claim 1 wherein the image file comprises embedded data, and wherein the embedded data facilitates reconstruction of the second image without referring to data in another image file.

7. The method of claim 1 wherein the difference between the image data for the first image and the image data for the second image comprises differences between plural quantized transform coefficients for the first image and plural quantized transform coefficients for the second image.

8. The method of claim 1 further comprising, before the storing the delta image metadata and the information representing the difference:

comparing a difference measure for the difference with a threshold; and

classifying the second image as a delta image based on the comparing.

9. The method of claim 8 further comprising:

calculating a new difference between the image data for the second image and image data for a third image of the plural images in the burst mode image series;

comparing a difference measure for the new difference with the threshold;

classifying the third image as a delta image based on the comparing the difference measure for the new difference with the threshold; and

storing information representing the new difference as a delta image file for the third image.

10. The method of claim 8 further comprising:

calculating a new difference between the image data for the second image and image data for a third image of the plural images in the burst mode image series;

comparing a difference measure for the new difference with the threshold;

classifying the third image as a full image based on the comparing the difference measure for the new difference with the threshold; and

storing information representing the image data for the third image as a full image file.

11. The method of claim 1 wherein the first image is earlier in time than the second image.

12. The method of claim 1 wherein the first image is later in time than the second image.

13. The method of claim 1 wherein the obtaining comprises capturing the image data for each of the plural images in the burst mode image series.

14. The method of claim 1 further comprising, after the obtaining, for each of the plural images in the burst mode image series:

performing a forward frequency transform on image data for the image to produce transform coefficients for the image; and

quantizing the transform coefficients for the image;

wherein the calculating the difference is performed after the quantizing between the quantized transform coefficients for the first and second images, respectively.

15. One or more computer-readable storage media having stored thereon a data structure comprising metadata for one or more images in a burst mode image series, the data structure comprising:

an image format identifier field comprising an identifier of a linked burst mode image format;

a root image identifier field comprising an identifier of a root image for the burst mode image series; and

an image index field comprising an index value representing an index of a given image in the burst mode image series.

16. The computer-readable storage media of claim 15 wherein the data structure further comprises a full image field comprising a bit that indicates whether the given image is a full image or a delta image.

17. The computer-readable storage media of claim 15 wherein the image index field indicates that the given image is the root image, and wherein the data structure further comprises one or more embedded data fields.

18. The computer-readable storage media of claim 15 wherein the image index field indicates that the given image is the root image, and wherein the data structure further comprises:

a start index field comprising a start index value representing a starting index for the burst mode image series; and

an end index field comprising an end index value representing an ending index for the burst mode image series.

19. The computer-readable storage media of claim 18 wherein the starting index for the burst mode image series corresponds to an image that is earlier in time relative to the root image, and wherein the ending index for the burst mode image series corresponds to an image that is later in time relative to the root image.

20. A computing device comprising one or more processors, an image capture device, a display, and one or more computer readable storage media having stored therein computer-executable instructions for performing a method comprising:

with the image capture device, capturing image data for each of plural images in a burst mode image series;

classifying a first image of the plural images in the burst mode image series as a root image;

calculating a difference between the first image and a second image of the plural images in the burst mode image series;

classifying the second image as a delta image based on the difference;

storing root image metadata and information representing the image data for the first image as a root image file, the root image metadata comprising a first set of one or more image metadata linker fields;

storing delta image metadata and information representing the difference, the delta image metadata comprising a second set of one or more image metadata linker fields that link the second image to the first image; and

displaying an indicator of the burst mode image series in a library view on the display, the indicator comprising a thumbnail version of the root image.