Method for preparing compressed image data file, image data compression device, and photographic device

• US 20070098284A1
• Filed: 10/06/2006
• Published: 05/03/2007
• Est. Priority Date: 04/09/2004
• Status: Active Grant

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Atsumi, Eiji, Sasaki, Hiroshi
• Granted Patent: US 7,477,796 B2
• Time in Patent Office: Days
• US Class Current: 382/239
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A method for carrying out a step of extracting a portion of a predetermined size from the image data, and a step of preparing a predetermined number of compressed partial data compressed with different compression parameter values by repeating preparation of compressed partial data by compressing the partial data in predetermined format for the predetermined number of times with the compression parameter value used in the predetermined format changed for each compression, on the entire image data. The method also calculates the total of the data sizes of all of the compressed partial data compressed with the same compression parameter value for each of the compression parameter values and prepares the compressed image data file from compressed partial data compressed with a compression parameter value for which the total is not larger than a given threshold and which is the closest value to the threshold.

Claims

1. A method for preparing a compressed image data file by compressing image data, the method comprising:

extracting a portion of a predetermined size from the image data, and

preparing a predetermined number of compressed partial data compressed with different compression parameter values from the partial data by repeating preparation of compressed partial data by compressing the partial data in predetermined format for the predetermined number of times with the compression parameter value used in the predetermined format changed for each compression, on the entire image data, and

the method further comprising calculating the total of the data sizes of all of the compressed partial data compressed with the same compression parameter value for each of the compression parameter values and preparing the compressed image data file from compressed partial data compressed with a compression parameter value for which the total is not larger than a given threshold and which is the closest value to the threshold.

2. The method according to claim 1, wherein when the total is larger than the threshold for all of the compression parameter values, the compressed image data file is prepared from compressed partial data compressed with a compression parameter value for which the total is the smallest.

3. The method according to claim 1, wherein the predetermined format is a JPEG format.

4. The method according to claim 3, wherein the compression parameters are Q factors or Q tables defined in JPEG format.

5. An image data compression device which compresses image data to prepare a compressed image data file, the device comprising:

partial data acquiring means,

interleave compression means, and

data file preparing means,

wherein

the partial data acquiring means acquires a portion of a predetermined size from the image data,

the interleave compression means prepares a number of compressed partial data compressed with different compression parameter values from the partial data by repeating preparation of compressed partial data by compressing the partial data in predetermined format for a predetermined number of times with the compression parameter value used in the predetermined format changed for each compression and outputs the compressed partial data sequentially, and

the data file preparing means calculates the total of the data sizes of all of the compressed partial data compressed with the same compression parameter value for each of the compression parameter values and prepares the compressed image data file from compressed partial data compressed with a compression parameter value for which the total is not larger than a given threshold and which is the closest value to the threshold.

6. The device according to claim 5, wherein when the total is larger than the threshold for all of the compression parameter values, the compressed image data file is prepared from compressed partial data compressed with a compression parameter value for which the total is the smallest.

7. The device according to claim 5, wherein the predetermined format is a JPEG format.

8. The device according to claim 7, wherein the compression parameters are Q factors or Q tables defined in JPEG format.

10. The device according to claim 7, wherein when the total is larger than the threshold for all of the compression parameter values, the data size determining section determines that a compression parameter value for which the total is the smallest is an optimum compression parameter value.

9. An image data compression device which compresses image data to prepare a compressed image data file, the device comprising:

an image data compression section, and

a data file preparing section,

wherein

the data compression section comprises;

a partial data acquiring section,

an interleave compression section, and

a data output section,

the partial data acquiring section takes in a portion of a predetermined size from the image data and stores the partial data temporarily,

the interleave compression section compresses the partial data stored in the partial data acquiring section in predetermined format to prepare compressed partial data,

the data output section outputs the compressed partial data,

the interleave compression section comprises a number of compression parameter values used in the predetermined format and prepares a number of compressed partial data compressed with different compression parameter values from the partial data,

the data output section outputs the compressed partial data sequentially,

the data file preparing section comprises;

a data input section,

a data storing section,

a data size calculating section,

a data size determining section, and

a data shaping section,

the data input section inputs the output compressed partial data,

the data storing section stores the compressed partial data input from the data input section,

the data size calculating section calculates the total of the data sizes of all of compressed partial data prepared from the same image data and compressed with the same compression parameter value out of the compressed partial data input from the data input section for each of the different compression parameter values,

the data size determining section determines that a compression parameter value for which the total is not larger than a given threshold and which is the closest value to the threshold is an optimum compression parameter value, and

the data shaping section prepares the compressed image data file from compressed partial data compressed with the optimum compression parameter value.

11. The device according to claim 9, wherein the interleave compression section gives markers indicating the compression parameter values used for compression to the compressed partial data.

12. The device according to claim 9, wherein the predetermined format is a JPEG format.

13. The device according to claim 12, wherein the compression parameters are Q factors or Q tables defined in JPEG format.

14. The device according to claim 12, wherein an RST marker defined in JPEG format is used as the marker.

15. The device according to claim 14, wherein the data shaping section removes the RST markers from the compressed partial data and gives new RST markers to the compressed partial data in accordance with JPEG standard.

16. A photographic device comprising:

a camera module, and

a host module,

wherein

the camera module comprises;

a sensor section,

an image data preparing section,

a camera-module-side data storing section,

a partial data acquiring section,

an interleave compression section, and

a data transmitting section,

the sensor section converts incoming light into an electrical signal,

the image data preparing section prepares image data from the electrical signal,

the camera-module-side data storing section stores a part or all of the image data temporarily,

the partial data acquiring section takes in a portion of a predetermined size from the image data stored in the camera-module-side data storing section and stores the partial data temporarily,

the interleave compression section compresses the partial data stored in the partial data acquiring section in predetermined format to prepare compressed partial data,

the data transmitting section transmits the compressed partial data to the host module,

the interleave compression section comprises a number of compression parameter values used in the predetermined format and prepares a number of compressed partial data compressed with different compression parameter values from the partial data,

the data transmitting section transmits the compressed partial data sequentially,

the host module comprises;

a data receiving section,

a host-side data storing section,

a data size calculating section,

a data size determining section,

a data shaping section, and

a file storage unit,

the data receiving section receives the data transmitted from the camera module,

the host-side data storing section stores the compressed partial data received by the data receiving section,

the data size calculating section calculates the total of the data sizes of all of compressed partial data prepared from the same image data and compressed with the same compression parameter value out of the compressed partial data received by the data receiving section for each of the different compression parameter values,

the data size determining section determines that a compression parameter value for which the total is not larger than a given threshold and which is the closest value to the threshold is an optimum compression parameter value,

the data shaping section prepares a compressed image data file including information of the entirely compressed image data from compressed partial data compressed with the optimum compression parameter value, and

the file storage unit stores the compressed image data file.

17. The device according to claim 16, wherein when the total is larger than the threshold for all of the compression parameter values, the data size determining section determines that a compression parameter value for which the total is the smallest is an optimum compression parameter value.

18. The device according to claim 16, wherein the host module has a telephone function.

19. The device according to claim 18, wherein the host module has a telephone function using CDMA.

20. The device according to claim 16, wherein the image data preparing section in the camera module prepares preview image data for preview from the electrical signal before preparing the image data, and the data transmitting section in the camera module transmits the preview image data to the host module before transmitting the compressed partial data, and

the host module comprises a display device and receives the preview image data and displays it on the display device.

21. The device according to claim 16, wherein the data compression section in the camera module prepares partial data for preview image whose resolution is lower than the partial data from the partial data, and the data transmitting section in the camera module transmits the partial data for preview image prepared from the partial data and the compressed partial data sequentially, and

the host module comprises a display device and stores the partial data for preview image in the host-side data storing section, prepares image data for preview of the image data from the partial data for preview image which is stored in the host-side data storing section by the data shaping section and displays the image data for preview on the display device.

22. The device according to claim 16, wherein the interleave compression section gives markers indicating the compression parameter values used for compression to the compressed partial data.

23. The device according to claim 16, wherein the predetermined format is a JPEG format.

24. The device according to claim 23, wherein the compression parameters are Q factors or Q tables defined in JPEG format.

25. The device according to claim 23, wherein an RST marker defined in JPEG format is used as the marker.

26. The device according to claim 25, wherein the data shaping section removes the RST markers from the compressed partial data and gives new RST markers to the compressed partial data in accordance with JPEG standard.