Image data coding and restoring method and appatatus for coding and restoring the same

Claim 2

The image data coding method according to claim 1 wherein the result of the determination is held until the image data of all the valid blocks in the present frame is coded and held the block information of all the blocks in the present frame is outputted together with the coded data of the valid blocks in the present frame.

Claim 3

The image data coding method according to claim 1 wherein the number of the valid blocks which are continuous after the valid block is outputted as the block information succeeding the coded data of the valid block based on the result of the determination.

Claim 4

The image data coding method according to claim 1 wherein the block information is coded and then outputted.

Claim 5

The image data coding method according to claim 1 wherein the image data of the valid blocks are coded using an orthogonal transform.

Claim 6

The image data coding method according to claim 1 wherein the determining steps (S1, S2) of determining that the image changes from the reference frame when the amount of the changes of the value of the predetermined image element within a block of the present frame compared to the corresponding image element of the corresponding block in the same position in the reference frame is more than the predetermined threshold value.

Claim 7

The image data coding method according to claim 6 wherein the amount of the change of the value of the predetermined image element is provided by the maximum value of the absolute value of the difference between the value of the predetermined image element in the block in the present frame and the value in the corresponding image element in the corresponding block in the reference frame in the same position as in the present frame.

Claim 8

The image data coding method according to claim 6 wherein the amount of the change in the value of the predetermined image element is provided by the sum of the absolute value of the difference between the value of the predetermined image element within a block of the present frame and the value of the corresponding image element of the corresponding block in the same position in the reference frame with regard to all the image element in respective blocks in the present frame.

Claim 9

The image coding method according to claim 6 wherein the amount of the change of the predetermined value of the image element is provided by the sum of the second power value of the difference between the predetermined value of the image element within a block of the present frame and the value of the corresponding image element of the corresponding block in the same position in the reference frame.

Claim 10

An image data coding apparatus for coding image data in units of block by dividing a frame into a plurality of blocks comprising: a reference frame holding means (612) for holding the image data of the reference frame; a present frame holding means (610) for holding the image data of the present frame; a determining threshold value holding means (618a) for holding a threshold value to determine whether the image within a block of the present frame changes from the corresponding image data of the block in the same position in the reference frame; change amount calculating means (614) for obtaining the amount of change of the predetermined value of the image element within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame; block change determining means (616) for determining the change of the image between the image within a block of the present frame and the corresponding image of the block in the same position in the reference frame; selecting means (618) for selecting only the image data of the valid block in which the image changes from the reference frame by said block change determining means (616), among the image data in respective blocks in the present frame held in the holding means (610); coding means (622, 624, 624a, 626, 626a) for coding the image data of the valid block inputted from the selecting means (618); outputting means (630) for outputting the result of the determination of the block change determining means (616) together with the coded data of the valid block generated from the coding means (622, 624, 624a, 626, 626a).

Claim 11

The image data coding apparatus according to claim 10 wherein the coding means (622, 624, 624a, 626, 626a) encodes the image data of the valid block by using an orthogonal transform.

Claim 12

The image data coding apparatus according to claim 10 further comprising: block information holding means (620) for holding the result of the determination by the block change determining means (616) with regard to all the blocks of the present frame; and coded data holding means (628) for holding the coded data of all the valid blocks in the present frame which are generated by the coding means (622, 624, 624a, 626, 626a); and wherein said outputting means (630) outputs the result of the determination of all the blocks in the present frame held in the block information holding means (620) and coded data of all the valid blocks in the present frame held in the coded data holding means in a switching manner.

Claim 13

The image data coding apparatus according to claim 10 further comprising: calculating means (670) for calculating the number of the continuous invalid blocks whose images are determined as non-changing from the image in the reference frame by using said block change determining means (616); and wherein the outputting means (630) outputs as the block information the number of continuous invalid blocks succeeding the valid block calculated by calculating means (670) after the coded data of the valid blocks is outputted.

Claim 14

The image data coding apparatus according to claim 10 further comprising: block information holding means (620) for holding the result of the determination by block change determining means (616) with regard to the blocks of the present frame; block information coding means (690) for coding the result of the determination of the block of the present frame held in the block information holding means (620) and for outputting it as block information and; coded data holding means (628) for holding the coded data of the valid blocks of the present frame generated by the coding means (622, 624, 624a, 626, 626a) and wherein said outputting means (630) outputs the block information generated by said block information coding means and the coded data of the valid blocks of the present frame held in the coded data holding means (628) in a switching manner.

Claim 15

The image data coding apparatus according to claim 10 wherein said amount-of-change calculating means (614) obtains the absolute value of the difference of the value of the predetermined image element within a block of the present frame compared to the corresponding image element of the block in the same position in the reference frame and provides the maximum value of the absolute value of the difference in respective blocks of the present frame as the amount of the change of the value of the predetermined image element.

Claim 16

The imaged data apparatus according to claim 10 wherein said amount-of-change calculating means (614) obtains the absolute values of the difference between the values of the predetermined image element within a block of the present frame compared to the corresponding image element of the block in the same position in the reference frame and provides the sum of the absolute value of the difference in respective blocks of the present frame as the amount of changes of the value of the predetermined image element.

Claim 17

The image data coding apparatus according to claim 10 said amount-of-change calculating means (614) obtains the difference in the image element within a block of the present frame compared to the corresponding image element of the block in the same position in the reference frame and provides the sum of the squares of the differences in the respective blocks in the present frame as an amount of the change in the value of the image element in respective blocks in the present frame.

Claim 18

A method of decoding image data according to claim 1 for decoding the image data comprising: the coded data of the image data of the valid block and the block information generated by said image data coding method comprising: step (S12) of decoding the image data of the valid block from the coded data; step (S14, S15) of updating an address of an image memory into which the image data of the valid block is written, based on the content of said block information; and step (S13) of writing the decoded image data of the valid block into the image memory in accordance with the updated address.

Claim 19

An image data decoding method according to claim 18, further comprising: wherein the step (S15) of updating the write address of the image memory for the image data of the valid block calculates the number of the continuous invalid blocks based on the block information.

Claim 20

The image data decoding method according to claim 18, further comprising: a step of separating the coded data of the valid block and the block information from the received input data.

Claim 21

The image data decoding method according to claim 18, further comprising: a step of decoding the coded block information.

Claim 22

The image data decoding method according to claim 18 for decoding the coded data of the image data of the valid block and the coded data of the block information generated by said image data coding method further comprising: step of decoding the coded data of the block information into the original information; step (S11, S12) of decoding the valid image data of the valid block from the coded data of the image data of the valid block; step (S14, S15) of updating a write address of an image memory for the image data of the valid block based on the content of the decoded block information and step (S13) of writing the decoded image data of the valid block into the image memory in accordance with the updated address.

Claim 23

The image data decoding apparatus according to claim 10 for decoding the code data and block information of the image data of the valid block generated by said imaged data coding apparatus further comprising: an image memory (658) for storing the decoded image data; decoding means (646, 648, 650) for decoding the image data of the valid block from the decoded data and address calculating means (654, 656) for calculating the write address of the image memory (658) for the image data of the valid block decoded by the decoding means (646, 648, 650) from the block information .

Claim 24

The image data decoding apparatus according to claim 23 wherein said address calculating means (654, 656) calculates the number of continuous invalid blocks from the block information and obtains the write address of the decoded image data.

Claim 25

The image data decoding apparatus according to claim 23 further comprising: separating means (640) for separating the coded data and the block information of the image data from the received input data.

Claim 26

The image data decoding apparatus according to claim 13 for decoding the coded data of the image data of the valid block generated by the image data coding apparatus further comprising: image memory (658) for storing the decode image data; decoding means (646, 648, 650) for decoding the image data of the valid block from the decoded data; and address calculating means (682, 656) for calculating the write address of the image memory (558) for the image data decoded by the decoding means (648).

Claim 27

The image data decoding apparatus according to claim 26 wherein said address calculating means (652, 656) obtains the write address of the decoded image data based on the number of the continuous invalid blocks of the block information.

Claim 28

The image data coding apparatus according to claim 26 further comprising: separating means (640) for separating the coded data and block information of the image data from the received input data.

Claim 29

The image data decoding apparatus according to claim 14 for decoding the image data from the coded data of the valid block and the coded data of the block information further comprising: image memory (658) for storing the decoded image data; decoding means (646) for decoding the image data of the valid block from the coded data of the image data; decoding means (696) for decoding the coded data of the block information into the block information; and address calculating means (654, 656) for calculating the writing address of the image data decoded by the decoding means (646).

Claim 30

The image data decoding apparatus according to claim 29 wherein said address calculating means (654, 656) obtains the write address of the decoded image data by calculating the number of continuous invalid blocks from the block information.

Claim 31

The image data decoding apparatus according to claim 29 further comprising: a separating means (640) for separating the coded data of the image data and the coded data of the block information from the input data.

Claim 32

An encoding method of the continuous image comprising: a step of encoding a refresh frame; and a step of dividing said encoding step into a plurality of sub steps.

Claim 34

An image data encoding apparatus for encoding continuous image data comprising: a reference frame holding means (11) for holding the image data of the reference frame; a present frame holding means (12) for holding the image data of the present frame; determining threshold value holding means (13) for holding the threshold value which is to be used for determining the existence of the change of the image within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame; block change determining means (14) for obtaining an amount of the change of the value of the predetermined image within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame held in the reference frame holding means (11) and for determining the change of the image within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame; block information holding means (15) for holding the result of the determination with regard to respective blocks of the present frame obtained by the block change determining means (14) as the block information; coding means (16) for, based on said block information, coding only the valid block of the present frame which is determined as having the change from the corresponding block in the reference frame when the present frame is not the refresh frame and coding all the blocks of the present frame by dividing it into said valid blocks and including the invalid blocks which are determined not having the change from the image in the reference frame when the present frame is the refresh frame; wherein said reference frame holding means (11) updates the image data within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame.

Claim 35

The image data coding apparatus according to claim 34, further comprising: a refresh signal generating means (19) for outputting a refresh signal designating that the present frame is the refresh frame, to the encoding means (16) and the reference frame holding means (11) when the number of frames encoded by the encoding means (16) reaches the predetermined value.

Claim 37

The image data encoding apparatus for encoding continuous image data comprising: a reference frame holding means (21) for holding image data of the reference frame; the present frame holding means (22) for holding the image data of the present frame; determining threshold value holding means (23) for holding a threshold value to be used for determining the existence of the change of the image within a block of the present frame compared to the corresponding image of the block in the same position in the reference frame; block determining means (24) for obtaining an amount of the changes of the value of the predetermined image element in respective blocks in the present frame held in the present frame holding means (22) from the corresponding one held in the reference frame holding means (21) at the same position as the corresponding one in the present frame and determines whether image in respective blocks in the present frame changes from that in the reference frame by comparing said amount of changes with a threshold value held in the determination threshold value holding means (23); block information holding means (25) for holding the result of the determination of all the blocks of the present frame designated by the block change determining means (24) as block information; encoding means (26) for, based on the block information of respective blocks of the present frame held in the block information holding means (25), encoding only the valid block of the present frame which is determined as having the change from the corresponding one in the reference frame when the present frame is not a refresh frame and for coding all the blocks of the present frame when the present frame is the refresh frame; a frame changing means (27) for changing the reference frame holding means (21) to the present frame holding means (22) and for changing the present frame holding means (22) to the reference frame holding frame means (21) where the present frame coded by the holding means (26) is a refresh frame and wherein said reference frame holding means (21) updates the image data of the block in the reference frame at the same position as the encoded valid block of the present frame to the image data of the valid frame block in the encoded present frame when the encoded present frame is not a refresh frame.

Claim 40

A method of encoding the image data according to the claim 39 wherein said third step (S132-S135) is applied to a first frame or any frame and the first step (S101) uses the threshold values determined by any preceding frame in the third means S132-S135) which is performed precedingly.

Claim 42

A method of decoding the image data according to claim 41 wherein: said second means (3022) is applied to only a first frame or any frame and the threshold value determined for the preceding frame in the second means (3022) in the preceding stage is used in the first means (1030) when the succeeding frame is encoded.

Claim 43

An image data encoding apparatus for encoding continuous image data comprising: reference frame holding means (31) for holding an image data of a reference frame; present frame holding means (32) for holding an image data of the present frame; determining threshold value holding means (33) for holding a threshold value to be used for determining the existence of change in the image within its respective block of the present frame from the corresponding image in the block in the reference frame in the same position as that of the present frame; block change determining means (34) for obtaining the amount of a change of the value of the predetermined image element in the respective block in the present frame held in the present frame holding means (32) at the same position as the corresponding image held in the reference frame holding means (31); encoding means (35) for encoding only a valid block which is determined as having a change in the image in the block in the present frame from the corresponding one in the reference frame by said block change determining means (34); determining threshold value changing means (36) for determining whether the threshold value held in the determining threshold value holding means (33) is appropriate, based on the amount of coded data produced by the encoding means (35), and for setting the value different from the said threshold value in the determining threshold value holding means (33) when the threshold value is not appropriate; and encoding data outputting means (37) for outputting the coded data encoded by the encoding means (35), when the threshold value held in the determining threshold value holding means (33) is determined as appropriate by the determining threshold value changing means (36).

Claim 44

An image data coding apparatus for coding continuous image data comprising: reference frame holding means (41) for holding the image data of the reference frame; present frame holding means (42) for holding the image data of the present frame; determining threshold value holding means (43) for holding the threshold value to be used to determine the existence of change in the image in the respective block in the present frame from the corresponding image in the block at the same position in the reference frame; block change determining means (44) for obtaining the amount of change in the value of the predetermined image element in the respective block of the image data of the present frame held in the present frame holding means (42) from the corresponding image element in the reference frame held in the reference frame holding means (41) at the same position as the corresponding one in the present frame and determining the existence of a change in the image in respective block of the present frame from the corresponding image in the block at the same position as the corresponding one in the present frame by comparing the amount of the change with the threshold value held in the determining threshold value holding means (43); determining threshold value changing means (45) for calculating the number of valid blocks of the present frame which are determined as having the change in the image from the reference frame, or the number of invalid blocks in the present frame which is determined as not having changed from the image in the reference frame, by means of the block change determining means (44), for determining whether the threshold value held in the determining threshold value holding means (43) is appropriate, based on the number of valid blocks or invalid blocks and for setting a value difference for the threshold value in the determining threshold value holding means (43) when the threshold value is not appropriate, and; encoding means (46) for encoding only the block of the present frame held in the present frame holding means (42), which is determined as the valid block by the block change determining means (44) when the threshold value held in the determining threshold value holding means (43) is determined to be appropriate by the determining threshold value changing means (45).

Claim 46

An image data encoding apparatus for encoding continuous image data comprising: reference frame holding means (51) for holding the image data of the reference frame; present frame holding means (52) for holding the image data of the present frame; a histogram preparing means (53) for obtaining the amount of change in the value of the predetermined image element which forms the reference values to be used, to detect the existence of change in the image in the respective block in the present frame from the corresponding image element in the block in the reference frame at the same position, based on the image data of the reference frame held in the reference frame holding means (51) and the image data of the present frame held in the present frame holding means (52) and preparing histogram of the present frame as a whole, with regard to the amount of the change of the present frame; determining threshold value setting means (54) for determining the threshold value to be used to determine the existence of change in the image in the respective blocks of the present frame from the corresponding one in the reference frame at the same position, based on the histogram prepared by the histogram preparing means (53); block change determining means (55) for comparing the amount of change in the value of the predetermined image element in the respective blocks of the present frame, obtained by the histogram preparing means (53) with the determining threshold value provided by the determining threshold value providing means (54) and for determining the existence of change in the image of the respective blocks in the present frame from the blocks in the reference frame at the same position as the corresponding image of the present frame; and encoding means (56) for encoding only the valid blocks which are determined as having changed the image by the block change determining means (55), and which are selected from all the blocks of the present frame.

Claim 47

The image data encoding apparatus according to claim 46, wherein said histogram preparing means (53) obtains the absolute value of the difference between the value of the predetermined image element in respective blocks in the present frame and that of the image element in the blocks in the reference frame at the same position as the corresponding one in the present frame, provides the maximum value of the absolute value of the difference in respective blocks of the present frame as the amount of change in the value of the predetermined image element and prepares a histogram with regard to the amount of change.

Claim 50

A method of encoding image data according to claim 49, wherein said second step (S152, S153) comprises a step (161) of changing the relation between the plurality of regions of the present frame and the plurality of threshold values assigned to the respective regions at a predetermined frame interval.

Claim 51

A method for encoding image data according to claim 49, wherein the threshold value assigned to the respective regions of the present frame in the second step (S152, S153) is changed in a predetermined frame interval.

Claim 52

The image data encoding apparatus for encoding the continuous image data comprising: a reference frame holding means (61) for holding the image data of the reference frame; a dividing means (62) for dividing the image data of the present frame into a plurality of regions; a determining threshold value outputting means (63) for outputting the threshold value to be used to detect the existence of change in the image in the respective block in the respective regions in the present frame from the corresponding image in the respective block in the respective region in the reference frame, each respective regions comprising a plurality of blocks and being provided by the dividing means (62); the block change determining means (64) for obtaining the amount of change in the value of the predetermined element in the block of the present frame from the corresponding image element in the block in the reference frame held in the reference frame holding means (61), with regard to the respective blocks in the respective regions of the present frame which are obtained in accordance with the output of the dividing means (62), comparing the amount of change with the threshold value inputted from the determining threshold value outputting means (63) and for determining the existence of change in the image in the respective blocks regarding the respective regions of the present frame from the corresponding image in the block in the reference frame at the same position; encoding means (65) for encoding only the valid block which is determined as having changed the image in the reference frame by means of block change determining means (64); block information outputting means (66) for outputting the result of the determination as the block information, by the block change determining means (64) wherein; the reference frame holding means (61) replaces the block in the reference frame at the same position as the valid block in the reference frame by the valid block of the present frame, based on the result of the determination by the block change determining means (64).

Claim 53

The image data encoding apparatus according to claim 52, wherein said determining threshold value outputting means (63) comprises the threshold value holding means (63b) for holding a plurality of threshold values and controlling means (63a) for switching the threshold value outputted to the block change determining means (64) from the threshold value holding means (63a) in accordance with respective regions of the present frame with a predetermined frame.

Claim 54

The image data encoding device according to claim 52, wherein said determining threshold value outputting means (63) comprises a threshold value holing means (63d) for holding a plurality of threshold values corresponding to a plurality of regions of the present frame; and control means (63e) for outputting the threshold value corresponding to the respective regions of the present frame from said threshold value holding means (63b) and threshold value changing means (63f) for obtaining the threshold value outputted from said threshold value changing means (63d) in accordance with the respective regions of the present frame to output the changed threshold value to the block change determining means (64).

Claim 56

The method of encoding the image data according to Claim 55 further comprises: steps (S25, S33, S53) of changing the determining threshold value in accordance with the result of determination by the present block; and determining steps (S21, S36, S54) of determining whether the adjacent block of the present block in the present frame is a valid block, using the changed determining threshold value.

Claim 57

The method of encoding of the image data according to Claim 56 wherein; the step (S23) of changing the determining threshold value decreases the determining threshold value when the present block is determined as being a valid block and the determining step (S21) determines the block following the present block as a valid block, based on the decreased determining threshold value.

Claim 58

The method of encoding the image data according to Claim 56 wherein; the step (S33) of changing the determining threshold value decreases the determining threshold value when the present block is determined as being a valid block, and the determining step (S36) determines again whether the block preceding the present block is a valid block, based on the decreased determining threshold value.

Claim 59

A method of encoding image data according to Claim 58, wherein; the step (S33) of changing the determining threshold value returns the determining threshold value to an original value, when the present block is determined as being an invalid block.

Claim 60

The method of encoding the image data according to Claim 56, wherein; the result of the determination of the present block in the determining steps (S52, S72, S76), and the result of the determination steps (S54, S79, S80) of the consecutive block based on the determining threshold value changed by the determining threshold value changing steps (S53, S78) determine whether the present block is a valid block.

Claim 61

The method of encoding the image data according to Claim 60, wherein; the determining threshold value changing step (S53) increases the determining threshold value when the determining step (S52) determines that the present block is the valid block, and the determining step (S54) determines whether the block following the present block is a valid block based on the changed determining threshold value and the present block is determined as being the valid block, when the result of the determination shows a valid block.

Claim 62

The method of encoding the image data according to Claim 60, wherein: when the present block is determined as being the invalid block in the determining step (S72), the determining threshold value changing step (S75) decreases the threshold value the determining step (S76) determines again the present block by using the changed determining threshold value, the determining threshold value is again increased when the present block is determined (S73) as being the invalid block by the next determination, it is determined (S79, S80) whether the adjacent block is as the valid block based on the increased determining threshold value and the present block is determined as the valid block, if the block preceding of the present block or the block succeeding the present block is the valid block, said preceding and succeeding block being included in the adjacent block.

Claim 63

An image data encoding apparatus encoding the continuous image data comprising; a reference frame holding means (702) for holding the image data reference frame; a present frame holding means (700) for holding the image data of the present frame; determining threshold value holding means (706) for holding the threshold value which is used to determine the existence of change in the image of the block in the present frame compared to the corresponding image of the block at the same position in the reference frame and block change determining means (704) for obtaining the amount of the change in the value of the predetermining image element with regard to the image data in the present frame held in the present frame holding means (700) compared to the corresponding image data in the block in the same position in the reference frame held in the reference frame holding means (702), comparing the amount of change within the threshold value held in the determining threshold value holding means (706), determining a valid block in which the image changes in the block of the present frame compared to the corresponding image in the block in the same position in the reference frame, and changing determining threshold value output from the determining threshold value holding means (706) in accordance with the result of the determination; coding means (710) for coding the image data of the block which is determined as the valid block by the block change determining means (704).

Claim 64

The image data coding apparatus according to claim 63, wherein; the block change determining means (704) decreases the determining threshold value output from the determining threshold holding means (706) when the present block is determined as being a valid block, thereby using the determined threshold value determining whether the blocks is invalid.

Claim 65

The image data coding apparatus according to claim 63, further comprising; block information holding means (708), which holds the result of the determination of all the blocks of the present frame obtained by block change determining means (704) as block information.

Claim 66

The image data coding apparatus for coding continuous image data comprising; reference frame holding means (700) for holding the image data of the reference frame; present block holding means (700) for holding the image data of the present block; preceding block holding means (724) for holding the image data of the preceding block in the present frame; determining threshold value holding means (706) for holding the threshold value to be used for determining the existence of change in the image in the block in the present frame compared to the corresponding image in the block in the same position in the reference frame; block change determining means (722) for determining the amount of change in the value of the predetermined image element in the block in the present frame compared to the corresponding image in the same position in the reference frame with regard to the present block in the present frame in the present block holding means (700), and; determining that the preceding block of the present frame in the preceding block holding means (724) determines the valid block for the image in the block of the present frame compared to the corresponding image in the same position in the reference frame by comparing the amount of change with the threshold value held in the determining threshold value holding image (706) and; changing the value of the threshold output from the determining threshold value holding means (706), in accordance with the result of the determination; and coding means (710) for coding the image data of the block which is determined as being the valid block by the block change determining means (722, 742, 736); wherein the block change determining means (732) decreases the determining threshold value outputted from the determining threshold value holding means (706) when the present block is determined as the valid block and determines whether or not the reference block held in preceding block holding means (724) is the valid block by using the changed threshold value; and coding image data of the preceding block held in the block holding means (724) by using the holding means (710).

Claim 67

The image data coding apparatus for coding continuous image data comprising; the reference frame coding means (702) for holding the image data of the reference frame; the present block holding means (732) for holding the image data of the present block in present frame; the reference block holding means (724) for holding the image data of the reference block of the present frame; a determining threshold value holding means (706) for holding the threshold value for the determination of the existence of the change in the image in the block of the present frame compared to the corresponding image in the block in the same position in the reference frame; a block change determining means (736) for obtaining the amount of change in the value of the predetermined image element in the present block in the reference frame held in the present block holding means (732) or in the reference block held in the reference block means (734) compared to the corresponding image element in the block at the same position in the reference frame; comparing the amount of the change to the threshold value held in the determining threshold value holding means (706), in order to determine the valid blocks in which the image changes in the block of the present frame compared to the image in the block in the same position in the reference frame; and changing the value of the determining threshold value outputted from the determining threshold value holding means (706) in accordance with the result of the determination; holding means (710) for holding the image data of the block determined as a valid block by the block change determining means (736); wherein the determining threshold value outputted from the determining threshold value holding means (706) is increased when the block change determining means (706) determines that the present block is a valid block and determines whether the subsequent block is the valid block based on the changed determining threshold value and the coding means (710) encodes the image data of the present block held in the present block holding means (732) when the subsequent block is the valid block.

Claim 68

An image data coding apparatus for coding a continuous image data comprising; reference frame holding means (701) for holding the image data of the reference frame; preceding block holding means (724) for holding the image data in the preceding block of the present frame; present block holding means (732) for holding the image data in the present block of the present frame; subsequent block holding means (734) for holding the image data of the subsequent block in the present frame; threshold value holding means (706) for holding a threshold value to be used to determine the existence of the change in the image in the present block of the present frame compared to the corresponding image in the block in the same position in the reference frame; block change determining means (742) for obtaining the amount of change in the predetermined value of the image in the present block in the present frame held in the present block holding means (732), the preceding block held in the preceding block holding means (724) or the subsequent block held in the subsequent block holding means (734), compared to the corresponding image in the block at the same position in the reference frame in the reference frame holding means (701), comparing the amount of the change with the threshold value held in the determining holding means (706), determining the existence of the valid block which the image in the block in the present frame changes compared to the corresponding image in the same position of the reference frame; and changing the value of the threshold value outputted from the determining threshold value holding means (706) in accordance with the result of the determination; and coding means (710) for coding the image data of the block which is determined as the valid block by the block change determining means (742) and wherein said determining threshold value is outputted from the determining threshold value holding means (706) and is decreased when the block change determining means (740) determines that the present block is an invalid block and the coding means (710) encodes the image data of the present block when the preceding block is determined as being the valid block based on the changed determining threshold value or the subsequent block is determined as the valid block even if the preceding block is determined as the invalid block as a result of the above determination.