Method of compressing digital image data and device thereof

Claim 3

The method of compressing image data as claimed in claim 1, wherein said natural numbers M and N are both 8.

Claim 4

The method of compressing image data as claimed in claim 1, wherein said first edge value is normalized by a ratio of 10 10 divided by said first edge value.

Claim 5

The method of compressing data as claimed in claim 3, wherein said number of block allocation bits are determined by a first equation of (Ai/TY)(AL) for said luminance signal, where Ai represents said fourth edge value, TY represents said first edge value, A represents a predetermined number of image compression bits and L represents an allocation constant of said luminance signal, a second equation of (Ai/TR-Y)(AM) for said first chrominance signal, where TR-Y represents said second edge value and M represents an allocation constant of said first chrominance signal, and a third equation (Ai/TB-Y)(AN) for said second chrominance signal, where TB-Y represents said third edge value and N represents an allocation constant of said second chrominance signal.

Claim 6

The method of compressing data as claimed in claim 4, wherein said allocation constants of said luminance signal, said first and second chrominance signals are respectively set to equal to 0.76, 0.11 and 0.13.

Claim 7

An image data compression device having coding means, comprising: detection means connected to said coding means, for detecting first, second, third and fourth edge values respectively from a luminance signal, first and second chrominance signals and image blocks representative of a block format combination of said luminance signal and said first and second chrominance signals of said coding means; decision means for normalizing said first edge value to provide a quantization scaling factor; block bit allocation means for allocating a number of bits corresponding to said each image block according to said first, second, third and fourth edge values; and factor bit allocation means for subtracting a number of DC factor bits of each image block coded by a one-dimensional Huffman coding technique from a number of the block allocation bits allocated by said block bit allocation means to thereby allocate a number of AC factor bits.

Claim 8

An image data compression device having coding means, comprising: detection means connected to said coding means, for detecting first, second, third and fourth edge values respectively from a luminance signal, first and second chrominance signals and image blocks representative of a block format combination of said luminance signal and said first and second chrominance signals of said coding means; decision means for normalizing said first edge value to provide a quantization scaling factor; block bit allocation means for allocating a number of bits corresponding to said each image block according to said first, second, third and fourth edge values; and factor bit allocation means for subtracting a number of DC factor bits of each image block coded by a one-dimensional Huffman coding technique from a number of the block allocation bits allocated by said block bit allocation means to thereby allocate a number of AC factor bits.

Claim 9

The image data compression device as claimed in claim 6, wherein said detection means comprise: first edge detector means for detecting said first edge value in dependence upon said luminance signal; second and third edge detector means for detecting said second and third edge values in dependence upon said first and second chrominance signals; and fourth edge detector means for detecting said fourth edge value in dependence upon said image blocks.

Claim 10

The image data compression device as claimed in claim 7, wherein said decision means comprise: normalization means for normalization said first edge value by a ratio of 10 10 divided by said first edge value; and S-factor decision means for determining said quantization scaling factor according to a value normalized by said normalization means.

Claim 11

The image data compression device as claimed in claim 8, wherein said block bit allocation means comprises: first block bit allocator means for allocating a number of block allocation bits of said luminance signal on a basis of an equation of (Ai/TY)(AL), where Ai represents said fourth edge value, TY represents said first edge value, A represents a predetermined number of image compression bits and L represents an allocation constant of said luminance signal; second block bit allocator means for allocating a number of block allocation bits of said first chrominance signal on a basis of an equation of (Ai/TR-Y)(AM), where TR-Y represents said second edge value and M represents an allocation constant of said first chrominance signal; and third block bit allocator means for allocating a number of block allocation bits of said second chrominance signal on a basis of an equation of (Ai/TB-Y)(AN), where TB-Y represents said third edge value and N represents an allocation constant of said second chrominance signal.

Claim 12

The image data compression device as claimed in claim 9, wherein said allocation constants of said luminance signal, said first and second chrominance signals are respectively set to equal to 0.76, 0.11 and 0.13.

Claim 13

A data compression device, comprising: means for receiving an image signal representative of a luminance signal and first and second color-difference signals, and for formatting said image signal into a plurality of successive image blocks each having a predetermined size of pixels; detector means for detecting a plurality of edge values each representative of peripheral pixels of a plurality of addresses of a corresponding one of said luminance signal, said first and second color-difference signals and said image block; scaling factor means for providing a selected scaling factor in dependence upon a first edge value representative of said peripheral pixels of said plurality of addresses of said luminance signal; block bit allocation means for allocating a number of bits of each image block in dependence upon said plurality of edge values to provide a number of allocation bits; means for determining a quantized width of said image signal in dependence upon said selected scaling factor to provide a quantized width signal; means for quantizing said image signal in dependence upon said quantized width signal to provide a quantized sampled signal; first encoder means for encoding said quantized sampled signal to provide a first encoded signal having a number of discrete DC factor bits; factor bit allocation means for subtracting said discrete DC factor bits from said allocation bits to provide AC allocation bits; second encoder means for encoding said quantized sampled signal to provide a second encoded signal having a number of discrete DC factor bits in dependence upon said AC allocation bits; and means for multiplexing between said first and second encoded signals to provide a compresses image signal.

Claim 14

A data compression device, comprising: means for receiving an image signal representative of a luminance signal and first and second color-difference signals, and for formatting said image signal into a plurality of successive image blocks each having a predetermined size of pixels; detector means for detecting a plurality of edge values each representative of peripheral pixels of a plurality of addresses of a corresponding one of said luminance signal, said first and second color-difference signals and said image block; scaling factor means for providing a selected scaling factor in dependence upon a first edge value representative of said peripheral pixels of said plurality of addresses of said luminance signal; block bit allocation means for allocating a number of bits of each image block in dependence upon said plurality of edge values to provide a number of allocation bits; means for determining a quantized width of said image signal in dependence upon said selected scaling factor to provide a quantized width signal; means for quantizing said image signal in dependence upon said quantized width signal to provide a quantized sampled signal; first encoder means for encoding said quantized sampled signal to provide a first encoded signal having a number of discrete DC factor bits; factor bit allocation means for subtracting said discrete DC factor bits from said allocation bits to provide AC allocation bits; second encoder means for encoding said quantized sampled signal to provide a second encoded signal having a number of discrete DC factor bits in dependence upon said AC allocation bits; and means for multiplexing between said first and second encoded signals to provide a compresses image signal.

Claim 15

The data compression device as claimed in claim 11, wherein said second encoder means is operable in dependence upon a comparison on said number of discrete DC factor bits and said AC allocation bits for reducing bit truncation errors.

Claim 16

The data compression device as claimed in claim 12, wherein said predetermined size of pixels of each image block of said plurality of successive image block is 8×8.

Claim 17

The data compression device as claimed in claim 13, wherein said selected scaling factor is within a value of 0 and 5.12.

Claim 18

The data compression device as claimed in claim 12, wherein said scaling factor means comprises: normalization means for normalizing said first edge value representative of said luminance signal by dividing said first edge value into a factor of 10 10 to provide a normalized value; and decision means for providing said selected scaling factor in dependence upon said normalized value.

Claim 19

The data compression device as claimed in claim 12, wherein said detector means comprises: first edge detector means for detecting peripheral pixels of said plurality of addresses of said luminance signal to provide said first edge value; second and third edge detector means for respectively detecting peripheral pixels of a plurality of addresses of said first and second color-difference signals to provide second and third edge values; and fourth edge detector means for detecting peripheral pixels of a plurality of addresses of said image blocks to provide a fourth edge value.

Claim 20

The data compression device as claimed in claim 16, wherein said block bit allocation means comprises: first block bit allocator means for allocating a number of block allocation bits of said luminance signal in dependence upon a product of a ratio of said fourth edge value over said first edge value and a first constant; second block bit allocator means for allocating a number of block allocation bits of said first color-difference signal in dependence upon a product of a ratio of fourth edge value over said second edge value and a second constant; and third block bit allocator means for allocating a number of block allocation bits of said second color-difference signal in dependence upon a product of a ratio of fourth edge value over said third edge value and a third constant.

Claim 21

The data compression device as claimed in claim 17, wherein each of said first, second and third constants is based on a predetermined number of image compression bits of 337.5 Kbits and a respective allocation constant of each of said luminance signals, said first and second color-difference signals having respective values of 0.76, 0.11 and 0.13.

Claim 22

A data compression device, comprising: means for receiving an image signal representative of a luminance signal and first and second color-difference signals, and for formatting said image signal into a plurality of successive image blocks each having a predetermined size of pixels; detector means for detecting a plurality of edge values each representative of peripheral pixels of a plurality of addresses of a corresponding ones of said luminance signal, said first and second color-difference signals and said image block; scaling factor means for providing a selected scaling factor in dependence upon a first edge value representative of said peripheral pixels of said plurality of addresses of said luminance signal; block bit allocation means for allocating a number of bits of each image block in dependence upon said plurality of edge values to provide a number of allocation bits; means for quantizing said image signal in dependence upon said selected scaling factor to provide a quantized sampled signal; factor bit allocation means for subtracting a number of discrete DC factor bits of said quantized sampled signal from said allocation bits to provide AC allocation bits; and means for encoding said quantized sampled signal to provide an encoded signal having a number of discrete DC factor bits in dependence upon said AC allocation bits.

Claim 23

A data compression device, comprising: means for receiving an image signal representative of a luminance signal and first and second color-difference signals, and for formatting said image signal into a plurality of successive image blocks each having a predetermined size of pixels; detector means for detecting a plurality of edge values each representative of peripheral pixels of a plurality of addresses of a corresponding ones of said luminance signal, said first and second color-difference signals and said image block; scaling factor means for providing a selected scaling factor in dependence upon a first edge value representative of said peripheral pixels of said plurality of addresses of said luminance signal; block bit allocation means for allocating a number of bits of each image block in dependence upon said plurality of edge values to provide a number of allocation bits; means for quantizing said image signal in dependence upon said selected scaling factor to provide a quantized sampled signal; factor bit allocation means for subtracting a number of discrete DC factor bits of said quantized sampled signal from said allocation bits to provide AC allocation bits; and means for encoding said quantized sampled signal to provide an encoded signal having a number of discrete DC factor bits in dependence upon said AC allocation bits.

Claim 24

The data compression device as claimed in claim 19, wherein said detector means comprises: first edge detector means for detecting peripheral pixels of said plurality of addresses of said luminance signal to provide said first edge value; second and third detector means for respectively detecting peripheral pixels of a plurality of addresses of said first and second color-difference signals to provide second and third edge values; and fourth edge detector means for detecting peripheral pixels of a plurality of addresses of said image blocks to provide a fourth edge value.

Claim 25

The data compression device as claimed in claim 20, wherein said block bit allocation means comprises: first block bit allocator means for allocating a number of block allocation bits of said luminance signal in dependence upon a product of a ratio of said fourth edge value over said first edge value and a first constant; second block bit allocator means for allocating a number of block allocation bits of said first color-difference signal in dependence upon a product of a ratio of fourth edge value over said second edge value and a second constant; and third block bit allocator means for allocating a number of block allocation bits of said second color-difference signal in dependence upon a product of a ratio of fourth edge value over said third edge value and a third constant.

Claim 26

The data compression device as claimed in claim 21, wherein each of said first, second and third constants is based on a predetermined number of image compression bits of 337.5 Kbits and a respective allocation constant of each of said luminance signals, and first and second color-difference signals having respective values of 0.76, 0.11 and 0.13.

Claim 29

The method as claimed in claim 23, wherein said plurality of edge values detecting step comprises the steps of: detecting peripheral pixels of said plurality of addresses of said luminance signal to provide said first edge value; respectively detecting peripheral pixels of a plurality of addresses of said first and second color-difference signals to provide second and third edge values; and detecting peripheral pixels of a plurality of addresses of said image blocks to provide a fourth edge value.

Claim 30

The method as claimed in claim 24, wherein said step of generating said allocation bits comprises the steps of: allocating a number of block allocation bits of said luminance signal in dependence upon a product of a ratio of said fourth edge value over said first edge value and a first constant; allocating a number of block allocation bits of said first color-difference signal in dependence upon a product of a ratio of said fourth edge value over said second edge value and a second constant; and allocating a number of block allocation bits of said second color-difference signal in dependence upon a product of a ratio of said fourth edge value over said third edge value and a third constant.

Claim 31

The method as claimed in claim 25, further comprising setting each of said first, second and third constants on a basis of a predetermined number of image compression bits of 337.5 Kbits and a corresponding allocation constant of each of said luminance signals, said first and second color-difference signals having respective values of 0.76, 0.11 and 0.13.