Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
1998-03-26
2001-01-09
Mehta, Bhavesh (Department: 2721)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S302000
Reexamination Certificate
active
06173089
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an image handling system including an image source and an image receiver linked to each other for transfer of pixel values, the image source transferring about the pixels to the receiver on a clock of pixels after block of pixels basis. The invention also relates to a method of operating such a system.
2. Description of the Related Art
Such an image handling system and method is known from PCT patent application WO 95/14349.
Conventionally the pixel values of pixels of an image are transferred line of pixels after line of pixels from an image source like a tuner to an image receiver like a display device.
Resolution of the image receiver is a cost factor. For example, a low resolution display device which displays one output pixel for each block of pixels in the image is usually less expensive than a higher resolution display device which displays an output pixel for each pixel in the image. It is therefore desirable to introduce different versions of the image handling system, which differ from each other in the resolution used by the image receiver. However, in order to obtain the lower resolution the pixel values of the pixels from each block need to be compounded. In principle this could be done in the image source, but to simplify the exchange of different image receivers and to keep down development cost, it is desirable to keep the image source the same for each version of the image handling system. In this way only one image source needs to be developed for several image receivers and the development cost of the image receivers could be spread over different types of image sources.
However, when the pixel values are transferred for line of pixels after line of pixels one or more line memories are needed in the image receiver to store pixel values that are transferred between the pixel values of pixels of one block for later compounding. This causes extra cost, thereby defeating the purpose of using different image receivers.
What is needed is a method of allowing interchangeable use of image receivers with mutually different resolutions in the image handling system, without requiring a change in the way the pixel values are transferred and without requiring a memory in the image receiver for pixel values of pixels that do not belong to a block and that are transferred between the pixel values for that block.
WO 95/14349 teaches a system in which an image is compressed for transfer between the image source and the image receiver. The image source represents the image in a Quadtree structure, which subdivides the image into a matrix of two times two blocks, each block in turn being subdivided into a matrix of two times two smaller blocks and so on recursively. When the content of the image is such that there is less than a predetermined amount of variation in a block, the smaller blocks contained in that block are pruned from the representation of the image. The image source transfers image details only for those blocks that have not been pruned to the image receiver. In addition the image source transfers a quadtree code to indicate which blocks have been pruned. Information about the pixels is transferred block after block, all of the unpruned smaller blocks contained in each particular block in a matrix being transferred before transferring information about any other block in that matrix.
This publication is concerned with compression of images by eliminating transfer of whole blocks depending on the image content. It gives no suggestion to order the transfer of pixel values in this way if no elimination of blocks is attempted.
SUMMARY OF THE INVENTION
The image transfer system according to the invention is characterized in that, independent of a content of the image, the image source transfers the pixel values of all pixels of each particular block consecutively without intervening transfer of pixel values of pixels from other blocks from the level to which the particular block belongs. Thus all of the pixel values of the image are transferred, irrespective of the content of the image, in a temporal order which groups the pixel values of pixels contained in a block consecutively, the pixel values of pixels from different blocks of the same level being transferred block after block. Thus blocks belonging to a matrix that is a subdivision of a block at a next higher level are also transferred consecutively without intervening pixels from other blocks of the next higher level.
The image receiver has a resolution which corresponds to any predetermined level of blocks. For each block of that predetermined level the pixel values arrive without intervening pixel values from other blocks of that predetermined level. Therefore no memory is needed for such intervening pixel values. A family of versions of the system is possible with image receivers having a resolution corresponding to any of the levels of blocks, also to individual pixels.
An embodiment of the image handling receiver according to the invention is characterized in that the image receiver is arranged to retain the image at a coarser resolution than a resolution of individual pixels, the image receiver retaining only one respective output pixel for each particular block of a predetermined level, the image receiver deriving the one respective output pixel for the particular block from the transferred pixels of that particular block. In this case the invention is used to connect an image receiver with a coarser resolution than individual pixels.
Another embodiment of the image handling system according to the invention is characterized in that the image source is arranged to transfer the blocks from each respective matrix in a same sequence according to their spatial position in the matrix. This makes it possible to use the same type of address generation for assigning display coordinates at all levels of blocks.
REFERENCES:
patent: 4751742 (1988-06-01), Meeker
patent: 4873577 (1989-10-01), Chamzas
patent: 5396237 (1995-03-01), Ohta
patent: 5590261 (1996-12-01), Sclarroff et al.
patent: WO/9514349 (1995-05-01), None
Mehta Bhavesh
Patel Kanji
Slobod Jack D.
U.S. Philips Corporation
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