Image analysis – Image compression or coding
Reexamination Certificate
1999-11-12
2001-06-12
Couso, Jose L. (Department: 2721)
Image analysis
Image compression or coding
Reexamination Certificate
active
06246797
ABSTRACT:
The present invention relates generally to the storage of still and video images in an image processing device or system, such as a digital camera or digital video camera or a computer based image storage system, and particularly to a system and method for storing images at different image quality levels and for enabling users to dynamically compress high quality images into lower quality images in order to free up storage for the storage of additional images.
BACKGROUND OF THE INVENTION
Digital cameras typically include either permanent internal storage, and/or removable storage, for storing images. For instance, many digital cameras use removable flash memory cards for storing images. Each flash memory card has a fixed amount of memory, and when the memory card is full it can be removed from the camera and replaced by another flash memory card. In addition, digital cameras typically have a built-in viewer that enables the user to review the images stored on the flash memory card (and/or in the internal memory) and to delete user specified ones of the stored images. Deleting stored images obviously creates room for storing additional images.
When a digital camera user is “in the field” he/she generally has a limited amount of image storage on hand. If all the available image storage is full, the user has the choice of either not taking any additional pictures, or of deleting pictures from the image storage devices on hand to make room for new images. While this is actually one level better than the situation with film cameras, in which the user is simply out of luck when all the available film has been used, it is the premise of the present invention that the current image storage limitations of digital cameras are caused, in part, by failure to fully exploit the advantages of having images stored in digital format.
Similar storage vs. image quality considerations also apply to digitally encoded video frames. In particular, for any given amount of storage space, such as in a digital video camera, the goal is to retain the best image quality for the amount of storage required for a given number of video frames. Current devices allow the user to select image quality prior to capturing a digital video image, but do not enable the user to effectively manage the storage space in the video camera with respect to video sequences already taken, other than by deletion.
It is an object of the present invention to provide a digital camera or digital video camera, or other constrained storage device, that can store images at a plurality of image quality (i.e., fidelity or resolution) levels and furthermore can reduce images initially stored at a first image quality level to a lower image quality level so as to reduce the amount of storage occupied by those images.
It is also an object of the present invention to provide space efficient and computationally efficient image and video handling mechanisms for other applications, including network connected image and video libraries, Internet web browsers executed by client computers coupled to server computers, cable television set top boxes having video storage capabilities, and so on.
SUMMARY OF THE INVENTION
In summary, the present invention is an image processing device or system, such as a digital camera or digital video camera or a computer based image storage system, that can store images at a number of different image quality levels. The image processing device includes a memory device and image management logic. The memory device stores image files that each represent a respective image, each image file having an associated image quality level corresponding to a quality level at which the corresponding image has been encoded. The image management logic includes data processing circuitry and state machines for storing and processing image data received from an image capture mechanism. More specifically, the image management logic includes image processing circuitry and one or more state machines for applying a predefined transform, such as a wavelet-like transform, to image data received from the image capture mechanism to generate transform image data and for applying a data compression method to the transform image data so as to generate an image file having an associated image quality level.
The image management logic also includes image reconstruction circuitry and one or more state machines for successively applying a data decompression method and an inverse transform to a specified one of the image files so as to generate a reconstructed image suitable for display on an image viewer.
Further, the image management logic includes image file size reduction circuitry and one or more state machines for reducing the size of an image file while minimizing the reduction in image quality level. This circuitry extracts a subset of the data in the specified image file and forms a lower quality version of the specified image file that occupies less space in the memory device than was previously occupied by the specified image data structure. As a result, the amount of space occupied by image files in the memory device can be reduced so as to make room for the storage of additional image files or to allow more rapid transmission in a restricted bandwidth environment.
In a preferred embodiment, the image transform data in an image file is organized on a bit plane basis such that image transform data for at least one bit plane is stored in distinct portions of the image data structure from image transform data for other bit planes. To generate a lower quality image file, the image size reduction circuitry extracts a portion of the image file that excludes the image transform data for at least one bit plane and replaces the image file with an image file containing the extracted portion. Further, the image data is also organized on a transform layer basis such that image transform data for at least one transform layer is stored in distinct portions of the image data structure from image transform data for other transform layers. The image size reduction circuitry can also generate a lower quality image file by extracting a portion of the image file that excludes the image transform data for at least one transform layer and replaces the image file with an image file containing the extracted portion.
REFERENCES:
patent: 5867602 (1999-02-01), Zandi et al.
patent: 5881176 (1999-03-01), Keith et al.
patent: 5966465 (1999-10-01), Keith et al.
Castor Jon S.
Chui Charles K.
Couso Jose L.
Pennie & Edmonds LLP
PicSurf, Inc.
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