Irreversible compression apparatus, and method and program for controlling operation of same
AssigneeFUJIFILM Corporation
InventorNatsuko Yoshimura
Life of this patent
Estimating the term…
Abstract
A compressed image, for which a desired SSIM value is obtained, is acquired when irreversible compression is performed. Specifically, a quadratic curve G2 is defined. Next, a compression ratio P4 is calculated. An image is irreversibly compressed at the compression ratio P4, the compressed image is decoded and an SSIM value S5 is calculated. If the calculated SSIM value S5 is outside an allowable range of the target SSIM value, then the quadratic curve G2 is corrected in such a manner that it will pass through an intersection C4 between the compression ratio P4 and the SSIM value S5, whereby a quadratic curve G3 is obtained.
Claims19
An irreversible compression apparatus for irreversibly compressing image data, comprising:
- an irreversible compression control device for controlling the irreversible compression apparatus, based upon a curve representing a relationship between compression ratio of irreversible compression and image quality of image data that has been irreversibly compressed, in such a manner that the image will be irreversibly compressed at a compression ratio that will result in a desired image quality;
- an image quality calculating device for calculating the image quality of the image data irreversibly compressed under control exercised by said irreversible compression control device;
- a curve correcting device for correcting the curve so as to satisfy a relationship between the compression ratio, which is used in control of the irreversible compression apparatus by said irreversible compression control device, and the image quality calculated by said image quality calculating device;
- and
- a control device for controlling said irreversible compression control device, said image quality calculating device and said curve correcting device in such a manner that control by said irreversible compression control device, calculation of image quality by said image quality calculating device and correction of the curve by said curve correcting device are repeated until the image quality calculated by said image quality calculating device attains the desired image quality.
A method of controlling operation of an irreversible compression apparatus for irreversibly compressing image data, comprising:
- an irreversible compression control device controlling the irreversible compression apparatus, based upon a curve representing a relationship between compression ratio of irreversible compression and image quality of image data that has been irreversibly compressed, in such a manner that the image will be irreversibly compressed at a compression ratio that will result in a desired image quality;
- an image quality calculating device calculating the image quality of the image data irreversibly compressed under control exercised by the irreversible compression control device;
- a curve correcting device correcting the curve so as to satisfy a relationship between the compression ratio, which is used in control of the irreversible compression apparatus by the irreversible compression control device, and the image quality calculated by the image quality calculating device;
- and
- a control device controlling the irreversible compression control device, the image quality calculating device and the curve correcting device in such a manner that control by the irreversible compression control device, calculation of image quality by the image quality calculating device and correction of the curve by the curve correcting device are repeated until the image quality calculated by the image quality calculating device attains the desired image quality.
A non-transitory computer readable storage medium for storing a computer-readable program for controlling a computer of an irreversible compression apparatus for irreversibly compressing image data, so as to:
- control the irreversible compression apparatus, based upon a curve representing a relationship between compression ratio of irreversible compression and image quality of image data that has been irreversibly compressed, in such a manner that the image will be irreversibly compressed at a compression ratio that will result in a desired image quality;
- calculate the image quality of the irreversibly compressed image data;
- correct the curve so as to satisfy a relationship between the compression ratio, which is used in control of the irreversible compression apparatus, and the calculated image quality;
- and
- repeat control of the irreversible compression processing, calculation of image quality and correction of the curve until the calculated image quality attains the desired image quality.
Dependencies are inferred from the claim text.