MXPA97004118A

MXPA97004118A - Compensation circuit for color image quality and method of control relation

Info

Publication number: MXPA97004118A
Application number: MXPA/A/1997/004118A
Authority: MX
Inventors: Lee Kwangchun; Ha Yeongho; Hong Kyongchul
Original assignee: Lg Electronics Inc
Priority date: 1996-06-04
Filing date: 1997-06-03
Publication date: 1999-04-06

Abstract

The present invention relates to a color image quality compensation circuit comprising a device for detecting whether a reference color signal is present in a color signal representing a color of a video image, a device for determining a type respective of a plurality of reference color types corresponding to a detected reference color signal; a device for providing preset compensation values, each value corresponding to a respective type of a plurality of reference color types; for adjusting the image quality of the video image according to one or said compensation values corresponding to said respective type of reference color.

Description

COMPENSATION CIRCUIT FOR IMAGE QUALITY ñ COLOR AND RELATED CONTROL METHOD BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention and invention relates to a circuit of ^ compensation for color image quality, and on the side of an improved color compensation circuit with which a color image quality is compensated for in reference to a color selected by a user.

DESCRIPTION OF THE CONVENTIONAL TECHNIQUE Because the color of the lens is more easily retained in human memory, color image display systems such as television receivers and computer monitors, there have been several approaches to adjust the quality of the color image. using the color of the skin as a reference color. Referring to Figure 1, one scope is to gather colors within peripheral portions of a "skin color axis" which is positioned at 123 ° with respect to the demodulation axis B-Y. Specifically, in order to produce several skin colors as a reference skin color, the phase-L of the R-Y design module is increased to move the skin.

R- And towards the skin color e and the green color phase (axis G-Y not shown) is lowered to move its axis towards the color axis of the skin so that the color phase of it is inside the peripheral portions of the skin core. Still more specifically, with reference to figure 2, in order to collect a color vector VI, which. has a positive phase angle with respect to the color axis The pLel, a VY component of the RY of the Vi, decreased to VR-0Y. Due to this d, the Vi now becomes a Vi + color veciner, which has a phase closest to the axis of skin color, thus producing the color co or a reference skin color. Similarly, when a VB-Y component of BY has a color vector V2, which has a 5? N negative phase angle with respect to the skin color axis, it is decreased to a VB-Y value, the vector e color V2 becomes a V2 color vec + or, which has a faso within the peripheral portions of the color axis * standing ?! , thus producing the color as a reference skin color. An example of such a conventional colloid skin compensation circuit is shown in FIG. 3. This compensation circuit includes a color-timing gate 1 for providing a color-synchronization signal derived from a mixed color image signal CVBS 5. oscillator 2 of 3.58 MHZ to provide a refec subcarrier signal fsc that is in synchronization with the chromatic timing signal; a separation unit 3 Y / C? ar < ? ^ separate the signals of Y (lurnmanci) and C (colori that come from the CVBS mixed signal, an amplifier 4 to amplify 1 <C signal that comes from the Y / C separation unit, a 5 color disinodulator 5, a delay unit ñ for Y signal retractor that comes from the Y / C separation unit 3 for a predetermined time, a matrix amplifier 7 and a phase detector 8 for detecting the phase of a signal C g: amplified from the amplifier 4 as a whole (on Ja 0 serial subcarrier of reference fsc provided from oscillator 2 of 3.58) The color demodulator 5 comprises a con-i role of tmte "a", a demodulator " b "of RY, a 90 degree phase shifter" c ", a demodulator" d "of BY and an" e "deviculator of GY The matrix amplifier 7 comprises mixers f, _, and h to mix the output from the unit of delay ñ and a color difference signal that comes from the color demodulator 5, and amplifiers 1, j, and coupled to them, respectively. The color demodulator 5 demodulates the signal C in demodulation signals R-Y and B-Y. The user adjusts the hue and color saturation in reference to the skin color produced on a presentation screen (eg, CPT color screen tube). Referring to Figure 3, the phase detector 8 detects whether a signal q? E represents the color of the skin in signal C. If the skin color is detected, the, j = * dye controller of the demodulator of color 5 is controlled to control the position of the de-modification axis towards the skin color axis. However, this conventional approach has its disadvantages. For example, if a color vector (v.gr-., V in Fig. 2) is adjusted to move toward the skin's lower axis, its component value (e.g., VR-Y) with respect to the The conventional deoding curve is reduced to another value (eg, VR-: LY) of a smaller amount, giving the total color density. In addition, the color is adjusted in reference to a skin color, being unable to respond to several skin color types and divi ually. Another conventional approach is now explained with reference to Figure 4. In this approach, the angle between the 5 axes of demodulation R-Y and B-Y is fixed at 112 ° (not at 90 ° as conventional), thus increasing the R-Y component. As shown in FIG. 5, the "c" detector of the color modulator 5 is this range is set at 112 °, compared to the color shifter shifter of FIG. 3 which is set at 90 °. The reference numerals in Figure 5 correspond to the same reference numbers in Figure 3. In addition, the G-Y axis (not shown) is fixed at an angle of 252 °. In this approach, since the signal axis is always maintained at the same fixed angle to obtain a stable skin color, when an input signal does not represent a skin color, an unnecessary color denaturation could occur.

* BRIEF DESCRIPTION OF THE INVENTION Accordingly, an object of the present invention is to provide a color image quality compensation circuit that overcomes the aforementioned problems encountered in the conventional art. To achieve the above object, a circuit of k compensates for image quality. The odor of the present invention, as defined and broadly incorporated herein, comprises means for detecting whether a reference color serial is present in a color signal representing a color of a video image; and means for adjusting the color image quality of the video image according to a preset value corresponding to a detected reference color signal. According to another aspect of the present invention, a color image quality compensation circuit comprises means for detecting whether a reference color signal is present in a color signal representing a color of a video image; means for determining a respective type of a plurality of reference color types corresponding to a detected reference color signal; means for providing pre-set compensation values, each value corresponding to a respective number of a plurality of reference color types; and means for adjusting the image quality of the video image according to one of the compensation values corresponding to the respective reference type of reference. The advantages, objects and additional features of the invention will become apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS ___, The present invention is fully understood and is based on the detailed description that will be given later and the attached drawings, which are given only by way of illustration, and therefore are not limiting of the present invention, and in which; 5 Figure 1 is a conceptual graph that represents a conventional approach to skin color compensation. Figure 2 is a detailed graphical representation of Figure 2. Figure 3 is a block diagram of a conventional skin color compensation circuit 0. Figure 4 is a conceptual graph representing another conventional approach to skin color compensation. Figure 5 is a block diagram of another conventional skin color compensation circuit. 5 is a conceptual block diagram of a color image quality compensation circuit of g? According to one embodiment of the invention, Figure 7 is a circuit diagram of an > :? color picture quality compensation switch * according to the embodiment of the present invention. Fig. 8 is a circuit diagram of the phase detector of Fig. 7. Fig. 1 is a circuit diagram of the skin color-type detector of Fig. 7. áL L < : Figures lOfi and 10B are graphs illustrating 0 saturation of color and brightness based on different d < "&skin; DETAILED DESCRIPTION OF THE INVENTION Figure 5 is a conceptual block diagram of an image quality compensation circuit at an angle according to an embodiment of the present invention. In this embodiment, several different types of skin color are used, e.g., Mongolian, Caucasian and black, as a color of 0 reference and each type differs from the other. To produce a particular skin color type, for example, in a CPT screen, the color compensation data, representing the color density, brightness, dye, etc., and corresponding each to a Each of the 5 different types of skin color are preset, for example, in the memo.

With reference to FIG. 5, the color image quality compensation circuit of the present invention, as incorporated herein, conceptually includes a skin-color detector 10 for detecting 5? N skin color; a skin color type detector? 0 to determine the type of skin color detected by the skin color detector 10; a skin color compensation unit 30 to provide the compensation or compensation that corresponds HE < The type of skin color determined by the detector of type 0 'skin color 20; and a presentation unit 40, v.yr ,. , a CPT, to present the color, which is compensated by the compensation data ,, Figure 7 shows a schematic of the color image quality compensation according to the embodiment of the present invention. The color compensation circuit, as incorporated herein, preferably includes a phase detector 8 'for detecting a skin color; a skin color type detector. 'to determine the type of skin color detected by e? phase detector 8 '; and a color compensation unit 10 'for providing a compensation signal representing preset compensation data corresponding to the type of skin color detected by the skin color type detector 9' .. In this compensation circuit , both the skin color and the skin color type are detected in reference to the phase of the signal representing the detected skin color; and "pre-set compensation data" representing the color characteristics, eg, color saturation and brightness, corresponding to the detected type of skin color; and the quality of the image that will be presented in a controlled screen based on the color of the skin and the type of skin color detected. Referring to FIG. 7, the leather skin detector 9 'and the color compensation unit 10' can be integrated into an icrocomput adora. The phase detector 8 '10 ~ receives the color carrier signal fsc and the signal C and determines whether a color Lel is present in the signal C. Other reference numbers in FIG. 7 correspond to the same reference numbers in FIG. Figure 3. Figure 8 shows a block diagram of the fae detector 8 'comprising amplifiers 10a, 10b and lOd, and a phase detection unit 10c. The unit of ^^ phase detection 10c compares the phase differences between the ^ fsc color subcarrier signal and C signal, which have been amplified at appropriate signal levels for the unit phase detection 10c by means of the amplifiers 10a and 10b, respectively, and produces a voltage output representing the phase difference between these two signals to determine whether or not a skin color is present in the signal C. This voltage output is amplified to a signal level suitable for the skin type detector 9 'by means of the amplifier lOd.

THE j & FIG. 1 illustrates the output voltage of the phase detector 8 'of FIG. 8 with the respective color bars. The "phase angle (0)" represents the phase angle of the signal C representing a respective color bar with respect to the demodulation axis. The output voltage of the phase detector 8 'is inversely proportional to the detected phase difference. Magenta, which has the smallest phase angle with respect to the desorption axis, has an output of 3.8V. The output of the phase detector which has the skin color * varies from 2.35V to 3.25V, which corresponds to a scale of phase angles of 115 ° ~ 130 ° with respect to the axis of design. BY, depending on the types of skin color. In accordance with the embodiment of the present invention, the output voltage of the phase detector 8 'with respect to the skin color types is set as follows: Type L: color - of Mongol skin; 3.0V Type?; color- of black, tanned or makeup skin: 3. IV Type 3: Caucasian skin color: .2V TABLE 1 ^^ Lf) twenty ? R After the phase detector 8 'detects the presence of skin color in the signal C, the detector * of type of skin color 9 'determines the type of skin color corresponding to the skin color selected from the following types: Mongolian skin color; skin color black, tan and makeup; and Caucasian skin color. Referring to Figure 9, in the skin color type 0 detector 9 ', as incorporated in the present, comparators Comp 1, Comp 2, Comp 3 and Comp 4 compare the output voltage received from the phase detector 8 'through non-inverting terminals (+) of the same with the reference voltages 2.95V, 3.05V, 3.15V and 3.25V applied to investment terminals (-) respectively, and each comparator 5 emits a value "0" or "1" which represents the result of the comparison with a respective terminal of the analog / digital conversion terminals AD1, AD2, AD3 and AD4 of a ricrocomputer. S The microcomputer converts the supplied values to 0 terminals AD1, AD2, AD3 and AD4 into a four-bit stream and determines the type of skin color based on this digital data bitstream, and provides pre-sent compensation data. that correspond to this bit stream. 5 For example, referring to Table 2, if the output values from AD1 to AD4 are a bitstream of "1000", this represents that an output voltage X of the phase-detector is between 2.95V and 3.05V. Then, it is determined that the type of skin color is Mongolian. Similarly *, if the 0 output values are "1100", the output voltage X is between 3.05V and 3.15V. Then, it is determined that the type of skin color is the skin color with makeup or the tanned skin color or the black skin color. Similarly, if the output values are "1110", the output voltage X is between 5 3.15V and 3.25V. Then, the color of pLel is the colloid Caucasian skin.

TABLE 2 ß OR Once the skin color type detector 9 'determines the type of skin color detected, it provides information representing the skin color type to the skin color compensation unit 5'. The skin color compensation unit 10 'reads said information every 1 msec, which corresponds to reading 15 times a field of a screen image to ensure its accuracy. From that information read 15 times, the information that has been read repeatedly more or more frequently can be considered co or the true value. The skin color compensation unit 10 'will send a pre-set compensation value which corresponds to that particular skin color type determined by the skin color detector, to adjust the quality of the image. to 5 color of the screen image. The compensation value that depends on the type of skin color is pre-established based on the following conditions. Figures 10A and 1DB show the normal level of brightness suggested by the Cornrnission Internationale de Eclairage with respect to brightness and color density of color of the skin referring to Mongolian, Caucasian and black skin colors. As shown in FIGS. 1A and 10B, the type of color of p can be determined based on the brightness and density of the color. For example, in Figure 10A, the density j & (or saturation) color increases in the order of Caucasian, 0 mongolic and tan (or black). Similarly, in 1 A FIG. 10B, the brightness of the color increases in the tanning (or black), Mongolian and Caucasian order. Therefore, the type of skin color can be expressed in reference to the brightness and density of the color. Referring to Tables 3A, 3B and 3C, 5 the axial values of coior are measured for samples of 10 people, and the compensation values that correspond to the skin type are determined as follows; Mongolian: brightness = 55, color density = 58 Tan: brightness - 35, color density = 65 0 Caucasian: brightness = 55, color density - 43 BOX 3A ß MONOGOLIC SKIN COLOR iW 20 r. ^ £ J 40 TABLE 3B ß CAUCASIAN SKIN COLOR 1 twenty # 40 TABLE 3C ß BLACK, TANNED OR MAKE UP SKIN COLOR isr twenty ? R In summary, according to the present invention, 40 as incorporated herein, the. phase detector receives the color subcarrier signal and the signal C of a video signal rnixta that represents a video image and detects the phase difference between these two signals, to detect if? This is a signal that shows the color of the skin in serial C. If the color * of the skin is present, the type of skin color detected is determined, call it skin color * »Mongolian; color- of black, tanned or machined skin or 5 Caucasian skin color. Then, preset compensation data are provided that correspond to that particular skin color type that represents color characteristics such as dye, color density and brightness, for - Mk adjust the image quality of the video image, As described above, in the color image quality compensation circuit according to the present invention, the color image quality is adjusted in real time in reference to the -t po of skin color detected from the mixed video signal. If a color is not present of skin, no adjustment is necessary. Although the preferred modalities of The present invention by illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope of the invention. scope and spirit of invention, as noted in the claims to exas. For example, according to the embodiment of the present invention described above, the skin color is used as a reference color. However, you can use different colors (such as sky blue, green color, etc.) as a reference color. Also, instead of using only one color (eg, skin color) as a n reference color can be used concup intnente _r \ w_ ß different colors as reference colors (eg skin color, sky blue color and green color).

Claims

NOVELTY OF THE INVENTION * CLAIMS

5 1"- A color image quality compensation circuit comprising: means for detecting whether a color-reference signal is present in a color signal representing a color of a video image; and means to

-ßß ijust the color image quality of the video image of

10 according to a preset value corresponding to a serial color detected.
2. A color image quality compensation circuit comprising: means for detecting whether a reference color signal is present in a color signal 5 representing a color of a video image; means for determining a respective type of a plurality of reference color types which correspond to a detected reference * reference signal; means for providing pre-set compensation values, each value corresponding to a respective 0 ipo of a plurality of reference color types; and means for adjusting the image quality of the video image according to one of said compensation values that correspond to said respective color-reference type.
3. A skin color compensation circuit comprising: means for detecting whether a skin color signal is present in a color serial representing a color of

'a video image; means to provide a pre-set compensation value corresponding to a detected skin color; and means to adjust the image quality of said

5 video image according to said preset value.
4"- A color-coded skin circuit comprising: means for detecting a color-of-skin color signal is present in a color signal representing a color of a video image; injects to determine a respective type 10 of a plurality of skin color types that correspond to a detected skin color serial; means for providing preset compensation values, each value corresponding to a respective type of a plurality of types of skin colors; and means for adjusting the image quality of the video image according to a compensation value corresponding to said respective type of a plurality of types. ¿5. The color image quality compensation circuit according to claim 1, wherein said reference color signal represents a reference color 20 selected by a user. 6. The color image quality compensation circuit according to claim 1, wherein said pre-set compensation value is related to one or more of brightness, color saturation and tint of the image of

25 video. 7 »~ The image quality compensation circuit 0

The color according to claim 1, wherein said reference color signal represents a reference color selected by a user. 8 .-- The image quality compensation circuit

5 in accordance with claim 2, wherein said pre-set compensation value is related to one or more of brightness, color saturation and dyeing of the video image. ' { Ék 9.- The skin color compensation circuit of

10 according to claim 3, wherein said pre-set compensation value is related to one or more of brightness, color saturation and dyeing of the video image. 10.- The skin color compensation circuit of

* according to claim 4, wherein said value-

15 preset compensation is related to one or more of brightness, color saturation and dyeing of the video image. , jfa 11. The skin color compensation circuit according to claim 4, wherein said plurality of skin color types includes one or more types of skin color.

20 Mongolian, Caucasian and black skin color. 12. The color image quality compensation circuit according to claim 5, wherein said reference color includes one more of the sky blue and green colors. 13. The color image quality compensation circuit according to claim 7, wherein said reference color has one or more colors of blue or green. 14. The color image compensation package according to claim 2, wherein said determination means includes means for repeatedly verifying the reference color signal detected by said detection means at a range of predetermined time and means to count a number that represents the frequency of said verification during a predetermined period. 15. The skin color compensation circuit according to claim 4, wherein said determining means includes means for repeatedly verifying the reference color signal detected by said detection means at a time interval. predetermined and reliable means 5 count a number representing the frequency of said verification during a predetermined period. 16. The color image compensation circuit according to claim 14, wherein said determining means further includes means a to determine the type 0 r-color reference specifics based on a counted number of said verification. 17. The skin color compensation circuit according to claim 15, wherein said means and determination further include means for determining the respective type of reference color based on a counted number of said verification.

18. A method for compensating image quality, including the steps of: detecting whether a color reference signal is present in a color signal representing a color of a video image; and setting i to 5 color image quality of the video image according to a preset value corresponding to the color-detected signal. 19. A method for compensating the image quality at j k color, comprising the asos of detecting whether a reference color signal is present in a color signal representing a color of a video image; determining a respective type of a plurality of reference color types corresponding to a detected reference color signal; providing preset compensation values, 5 each corresponding to a respective type of said plurality of reference color types; and adjusting the image quality of the video image according to one of said compensation values corresponding to said respective type of reference color., 0 20.- A method for compensating skin color, comprising the steps of: detecting * if a skin color signal is present in a color signal representing a color- of a video image; provide a pre-established compensation value that corresponds to the detected skin color; and 5 adjusting the image quality of said video image according to said preset value.

95

M 21.- A method for compensating the color of the pioL, comprising the steps of: detecting if a color serial of skin is present in a color signal representing a colloid a video image; determining a respective type of? na 5 plurality of skin color types corresponding to 1 A skin color signal detected; providing preset compensation values, each value corresponding to a respective type of a plurality of skin color types; k and adjusting the image quality of the video image according to a compensation value corresponding to said r -specific type of a plurality of types. 22. The method for compensating for the color image quality according to claim 18, wherein said

Í reference color signal represents a reference color,

15 and which further comprises the step of selecting said reference color by a user. - "sjá 23.- The method for compensating the color image quality according to claim 18, wherein said pre-set compensation value is related to one or

20 more than brightness, color saturation and dye of the video image. 24. The method for compensating the color image quality according to claim 19, wherein said reference color signal represents a reference color,

25 and which further comprises the step of selecting said reference color by a user.

The method for compensating the color image quality according to claim 19, wherein said preset compensation value is related to one or more brightness, color saturation and dyeing of the image of
5 video 26. The method of compensation of color * of the skin according to claim 20, wherein said preset compensation value is related to one or more of k hr i 1lo, color saturation * and dye of the image of video. The skin color compensation method according to claim 21, wherein said preset compensation value is related to one or more brightness, color saturation and dyeing of the video image.; 28.- The color compensation method of the skin of

** according to claim 21, wherein said plurality of color types of p includes one or more of the color types of Mongolian, Caucasian and black skin. 29. The color quality compensation method according to claim 22, wherein said reference color includes one more of the sky blue and green colors. 30. The color quality compensation method according to claim 24, wherein said reference color includes one more of the sky blue and green colors.