Patent Application
20080055653
The above and other aspects of the present invention will become more apparent from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings of which:
Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures.
The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiment of the invention and are merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiment described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
Referring to
The random producing unit 100 produces seed values and provides them to the dithering processing unit 150 to be described later. That is, as illustrated in
The dithering processing unit 150 determines mask matrixes by using the seed values provided from the random producing unit 100 and counting values obtained by counting the number of input frames. In addition, the dithering processing unit 150 carries out a dithering to input image signals r, g, and b by using the determined mask matrixes.
The adding unit 170 adds the dithered image signals to the input image signals r, g, and b and outputs image signals r′, g′, and b′ with improved image quality.
Referring to
The counting unit 111 counts the number of the input frames f, and outputs frame counting values fcnt. The period determining unit 113 determines whether the period T is changed to a frame, which is input at present, by using the frame counting values. That is, the period determining unit 113 determines that the period T is changed when a remainder fcnt % T is output as a value of ‘0’ after the frame counting values fcnt are divided by the period T.
The function unit 115 produces an initial value of a LFSR, which has a magnitude corresponding to the following EQN. [1], according to a clock t set therein when the value of ‘0’ corresponding to a case that the period T is changed and is output from the period determining unit 113.
2 LFSR
Here, the LSFR_BIT represents a bit number of the LSFR, the Image_H_size represents a horizontal magnitude of an input frame, and the Image_V_size represents a vertical magnitude of the input frame.
According to an analysis, EQN. [1] means that a magnitude of the LFSR should be larger than or identical to that of one frame of input images.
An example of an operation of the initial value producing unit 110 as described above is as follows. Assuming that the period T is ‘3’, if 0 frames are input, the remainder comes to ‘0’ and thus the function unit 115 produces an initial value. If 1 frame is input, the remainder comes to ‘1’ and thus the function unit 115 does not produce an initial value. If 2 frames are input, the remainder comes to ‘2’ and thus the function unit 115 also does not produce an initial value. Also, if 3 frames are input, the remainder comes to ‘0 and thus the function unit 115 produces an initial value. That is, the initial value of the LFSR is updated and output.
Referring to
The start point detecting unit 133 detects a start position of the input frame f, so that the switching unit 135 is turned on or off. That is, whenever a new frame f is input, the start point detecting unit 133 detects a start position of the input frame. At this time, preferably, but not necessarily, the start position of the input frame is detected before a picture displaying area is input.
The switching unit 135 switches the initial value produced by the initial value producing unit 110 explained with reference to
At this time, since the initial value producing unit 110 produces and outputs an initial value only when the period is changed, the LFSR 137 registers the same initial value for one period. For instance, assuming that a period T is ‘3’, an initial value produced by the function unit 115 when 0 frames are input is registered in the LFSR 137 while 0 frames, 1 frame and 2 frames are input. Also, while 3 frames, 4 frames and 5 frames are input, an initial value updated by the function unit 115 when 3 frames are input is registered in the LFSR 137.
The position change sensing unit 131 senses position (x, y) changes of pixels included in an input frame, and transmits a value to the LFSR 137. That is, the position change sensing unit 131 outputs ‘1’ if the position (x, y) of each of the pixels included in the input frame is determined as changed, and outputs ‘0’ if the position (x, y) of each of the pixels is determined as not changed.
The LFSR 137 registers the initial value produced by the initial value producing unit 110, and carries out an operation represented as the following EQN. [2] according to the outputs from the position change sensing unit 131 to produce seed values.
LFSR_STATE=(LFSR_STATE<<1)+F(x0,x2,xn-4,xn-1) EQN. [2]
Here, the LFSR_STATE<<1 represents that the LFSR 137 is shifted, and the F( ) represents an exclusive OR (XOR) function. Also, the x0,x2,xn-4, and xn-1 are taps, which are calculated by the XOR function. The number of the taps is set by a user.
The LFSR 137 carries out the operation of the mathematical formula 2 to produce a seed value whenever the position change sensing unit 131 outputs ‘1’. At this time, an output bit number of the LFSR 137 is determined by the following EQN. [3].
O_BIT=Round(log2(M×N)) EQN. [3]
Here, the O_BIT represents the output bit number of the LFSR 137, that is, a magnitude of the seed value, and the Round( ) means a rounding off to the nearest integer. Also, the M×N represents a magnitude of the mask matrix.
Referring to
The counting unit 151 counts the number of input frames f, and provides frame counting values frame cnt to the selecting unit 153.
As illustrated in
For instance, if a seed value is 2 and a frame count values frame cnt is T−1, a mask matrix corresponding thereto is selected, as illustrated in
In
Referring to
After that, when image signals are input, the counting unit 111 counts the number of input frames f, and outputs frame counting values fcnt (S210). At this time, the period determining unit 113 determines whether a period T is changed, by using a remainder fcnt % T obtained by dividing the frame counting values fcnt by the period T (S220).
That is, if the remainder fcnt % T is ‘0’, the period determining unit 113 determines that the period T is changed, and the function unit 115 produces a new initial value (S230). To the contrary, if the remainder fcnt % T is not ‘0’, the period determining unit 113 determines that the period T is not changed, and the function unit 115 does not produce a new initial value, but outputs an existing initial value as it is (S235).
Next, the start point detecting unit 133 determines whether a new frame is input (S240). That is, if the start point detecting unit 133 detects a start position of frame and determines that a new frame is input, the switching unit 135 is turned on, so that the LFSR 137 registers the initial value produced by the function unit 115 (S250)
At this time, the position change sensing unit 131 senses whether positions of pixels are changed (S260). That is, if the position change sensing unit 131 senses a position (x, y) change of each of the pixels included in input one frame and determines that the position (x, y) of each of the pixels is changed, the position change sensing unit 131 outputs ‘1’. To the contrary, if the position change sensing unit 131 determines that the position (x, y) of each of the pixels is not changed, the position change sensing unit 131 outputs ‘0’.
When the position change sensing unit 131 outputs ‘1’, the LFSR 137 carries out the operation represented as the above-described mathematical formula 2 according to the output from the position change sensing unit 131, and updates seed values (S270).
Next, the dithering processing unit 150 selects mask matrixes by using the seed values and the frame counting values counted by the counting unit 151 (S280), and carries out a dithering (S290).
With the process as described above, the image signal processing apparatus according to the exemplary embodiment of the present invention can carry out the temporal and the spatial dithering without using a frame buffer.
As apparent from the foregoing description, according to the exemplary embodiment of the present invention, the image signal processing apparatus and the method thereof carry out the dithering using the LFSR instead of the frame buffer, thereby allowing fabrication costs to be-reduced and allowing a high-definition image to be realized.
Although representative embodiment of the present invention has been shown and described in order to exemplify the principle of the present invention, the present invention is not limited to the specific embodiment. It will be understood that various modifications and changes can be made by one skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, it shall be considered that such modifications, changes and equivalents thereof are all included within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0083049 | Aug 2006 | KR | national |
