Image encoding apparatus, image decoding apparatus, image processing apparatus, and control method thereof dealing with high dynamic range image

Patent metadata

Field	Value
Publication number	US-9324164-B2
Application number	US-201414317707-A
Country	US
Kind code	B2
Filing date	Jun 27, 2014
Priority date	Jul 11, 2013
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

This invention makes it possible to detect only a relatively large mismatch while allowing a mismatch to some extent between an LDR image and HDR information, which are stored in a single file, caused by editing of the LDR image. An apparatus of this invention generates, from an input HDR image, an LDR image and difference information representing a difference between the LDR image and the HDR image. The generated LDR image is encoded. Information formed from data representing a local feature of the LDR image is calculated as LDR meta-data. The apparatus generates a file by storing the encoded data in a main encoded data storage region and storing the difference information and the LDR meta-data in a marker defined as a non-reference region for an LDR image decoding apparatus in the file structure.

First claim

What is claimed is:

1. An image encoding apparatus for encoding a High Dynamic Range image, comprising:
an input unit configured to input the High Dynamic Range image of an encoding target;
a generating unit configured to generate, from the input High Dynamic Range image, a Low Dynamic Range image and difference information representing a difference between the Low Dynamic Range image and the High Dynamic Range image;
an encoding unit configured to encode the Low Dynamic Range image generated by the generating unit;
a calculating unit configured to calculate, as Low Dynamic Range meta-data, information formed from data representing a feature of the Low Dynamic Range image; and
a file generating unit configured to generate a High Dynamic Range encoded file by storing encoded data of the Low Dynamic Range image generated by the encoding unit in a main encoded data storage region of a file structure for the Low Dynamic Range image and storing the difference information and the Low Dynamic Range meta-data in a marker defined as a non-reference region for a Low Dynamic Range image decoding apparatus in the file structure;
a memory storing a program; and
a processor configured to function as at least one of the units by executing the program stored in the memory,
wherein the calculating unit includes a reducing unit configured to generate one representative pixel from n×m pixels in the Low Dynamic Range image, thereby generating a Low Dynamic Range reduced image from the representative pixel, wherein n and m are each equal to or greater than 1,
wherein the encoding unit encodes the Low Dynamic Range reduced image as well, and
the file generating unit stores encoded data of the Low Dynamic Range reduced image in the marker as the Low Dynamic Range meta-data and generates the High Dynamic Range encoded file.

2. The apparatus according to claim 1 , wherein the encoding unit encodes the difference information as well.

3. The apparatus according to claim 1 , further comprising a hash value calculating unit configured to calculate a hash value from the Low Dynamic Range image,
wherein the file generating unit stores the hash value in the marker as well.

4. The apparatus according to claim 1 , wherein the calculating unit includes an edge image generating unit configured to generate, as the Low Dynamic Range meta-data, an edge image representing whether each pixel of the Low Dynamic Range reduced image is an edge pixel.

5. The apparatus according to claim 1 , wherein the calculating unit includes a meta-data generating unit configured to generate, as the Low Dynamic Range meta-data, a map image by dividing a dynamic range of the High Dynamic Range image by a preset division count, adding a number to a corresponding section of each pixel value of the Low Dynamic Range image corresponding to each divided section, and replacing the pixel value of the Low Dynamic Range image with the number of the corresponding section.

6. An image decoding apparatus for decoding a High Dynamic Range encoded file, comprising:
a decoding unit configured to decode encoded data of a Low Dynamic Range image stored in a main encoded data storage region of a file structure for the Low Dynamic Range image in the High Dynamic Range encoded file;
an extracting unit configured to extract Low Dynamic Range meta-data and difference information representing a difference between the Low Dynamic Range image and a High Dynamic Range image from a marker defined as a non-reference region for a Low Dynamic Range image decoding apparatus in the file structure;
a generating unit configured to generate the Low Dynamic Range meta-data from the Low Dynamic Range image decoded by the decoding unit;
a specifying unit configured to specify a state in which the Low Dynamic Range image decoded by the decoding unit is edited from an original Low Dynamic Range image using meta-data generated by the generating unit and the meta-data extracted by the extracting unit;
an output control unit configured to select based on the specifying result whether to generate and output the High Dynamic Range image from the difference information and the Low Dynamic Range image decoded by the decoding unit or output the Low Dynamic Range image decoded by the decoding unit;
a memory storing a program; and
a processor configured to function as at least one of the units by executing the program stored in the memory.

7. The apparatus according to claim 6 , further comprising an a Low Dynamic Range image judging unit configured to, when a hash value is stored in the marker, extract the hash value, calculate a hash value from the Low Dynamic Range image decoded by the decoding unit, compare the hash values, and when the hash values match, omitting judgment processing by the judging unit and judging that the Low Dynamic Range image decoded by the decoding unit remains unchanged from the original Low Dynamic Range image.

8. The apparatus according to claim 6 , wherein the specifying unit
extracts and decodes encoded data of a Low Dynamic Range reduced image from the marker,
generates the Low Dynamic Range reduced image from the Low Dynamic Range image decoded by the decoding unit,
judges whether a pixel value difference between the decoded Low Dynamic Range reduced image and the Low Dynamic Range reduced image obtained by reduction is not more than a preset allowable value, and
when the difference is not more than the allowable value, judges that editing within a preset allowable range has been performed for the Low Dynamic Range image obtained by the decoding unit.

9. The apparatus according to claim 6 , wherein the specifying unit
extracts an edge image from the marker,
generates the edge image from the Low Dynamic Range image decoded by the decoding unit,
judges whether pixel values of the extracted edge image match the pixel values of the generated edge image, and
upon judging that the pixel values match, judges that editing within a preset allowable range has been performed for the Low Dynamic Range image obtained by the decoding unit.

10. The apparatus according to claim 6 , wherein the specifying unit
extracts a map image from the marker,
generates, as the Low Dynamic Range meta-data, the map image by dividing a dynamic range of the High Dynamic Range image by a preset division count, adding a number to a corresponding section of each pixel value of the Low Dynamic Range image corresponding to each divided section, and replacing the pixel value of the Low Dynamic Range image with the number of the corresponding section,
judges whether pixel values of the extracted map image match the pixel values of the generated map image, and
upon judging that the pixel values match, judges that editing within a preset allowable range has been performed for the Low Dynamic Range image obtained by the decoding unit.

11. The apparatus according to claim 6 , further comprising a display control unit configured to perform display to cause a user to select based on the specifying result whether to generate and output the High Dynamic Range image from the difference information and the Low Dynamic Range image decoded by the decoding unit or output the Low Dynamic Range image decoded by the decoding unit.

12. A control method of an image encoding apparatus for encoding a High Dynamic Range image, comprising:
inputting the High Dynamic Range image of an encoding target;
generating, from the input High Dynamic Range image, a Low Dynamic Range image and difference information representing a difference between the Low Dynamic Range image and the High Dynamic Range image;
encoding the generated Low Dynamic Range image;
calculating information form

Assignees

• Canon Kk

Inventors

• Kikuchi Tomoe

Classifications

• H04N19/30

  using hierarchical techniques, e.g. scalability (H04N19/63 takes precedence) · CPC title

• H04N19/162

  User input · CPC title

• H04N19/60

  using transform coding · CPC title

• H04N19/14

  Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) · CPC title

• H04N19/46 Primary

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title