BACKROUND OF THE INVENTION In a color video camera, white balance is achieved whan a neutral white object imaged by the samara uni*r given illumination isrepresented as red (R), grean (G), and blue (B) signals having equal output levels. , White balance L- needed since the RGB representation produced by a color viieo camera typically changes as the illumination of a scene varies. In some circumstances, a color video camera white balanced for certain illumination conditions will not be white balanced for other illumination conditions. As a result, it is possibl that an object under two different ilumination will have two different RGB representations even though a human observer would perceive the object as having the same color under both illuminations, In a manual operation, white balance is achieved by imaging a neutral white object under the illumination of interest and adjusting the amplification of one or more of the red, green, and blue signals until their respective output level are equal. i In an automatic white balance (AWB) operation- a neutural white object under the illumination of interest is imaged. -,nd the Amplification ltvels of each of the red and blue signals are adjusted. For example, the output levels of the red and blue signals may be made equal to that of the green signal. In both operations, maintenance of white balance will deperd upon the onsistency of the illumination conditions and maintenance of the adjusted amplification levels. in an automatic tracing white balance (AT10 operation, the white balance operation is automatically repeatsily carried out during an ordinary imaging process. Since an oirSinary imaged scene may not contain a neutral white object, it is possible that the whita balance will be incorrectlV adjusted with reference to a colored object. Consequently, true white balance may not b« achieved, e g • a non- white color is represented as the color white. Figure 3 illustrates a bluck body radiation curve BBR, plotted on red signal gain vs. blue signal gain axes relative to red and blue signal amplifiers in a video camera. As shown, signal gain values aro represented by eight-bits and, accordingly, each axis extends from 0 tc 256. The red signel gain and blue signal gain axes intersect at the point (128, 128) . Xiao illustrated is a white area, indicated by slanted lining, which iB generally symmetric about the black body raiiation curve BBR. The white area represents red and blue signal values which are characteristic of the color white. To avoid the problem of incorrect white balance i adjustment during an XTW operation, the red and blue signal values representing an imaged scene may be compared to a predetermined set of red and blue signal values characteristic of che color white. The white area comprises such a set of red and blue aignal values characteristic of the color whit* Previously, it was attempted to manually calibrate the wnite are such that output levels of the respostive R, C and B signals are mutually equal when a reference light source is imaged. Kith reference to Figure 9,' calibration with reepect to a standard light source would be attained when the !i signal gain and the R signal gain are both equal; to 128. In practice, a variable resistance was provided to manually adjust white balance amplification while a tandard light source was imaged. A. manual aijustment was mafle of the ft signal and B signal output levels to make them equaation the G signal output level. Since the adjustment was made manually by a uoer or technician, errors in calibration have occurred and a precise adjustment has been difficult to achieve, is calibration introduces error into the ATW operation, reducing its effectiveness. Additionally, the introduction of manual adjustment arror may significantly limit further improvement in ATW processing efforts. Further errar is introduced if the setting of the variable resistance slifts after a manual adjustment. Repeated manual readjustment can be difficult. objects AND SUMMARY OF THE INVENTION Therefore, an object of thi present invent-on is to provide apparatus and methodology for an improved wh .te balance operation. Another object of the present invention 1 to provide an automatic white balance operation and an automat.c tracing white balance operation with improved accuracy and precision. Still another object of the present invention is to provide an adaptive automatic tracing white balance operation for precisely adjusting white balance baaed upon the results of previous automatic white balance operations. According to an aspect of the present invention, an imaging device is provided which includes an imaginr device that converts an image into a plurality of color signals each having a signal level; a white balance amplifier chat adjusts, the signal level of at least: one of the color signals to produse a plurality of amplified color signals; a calibration device that calibrates the white balance amplifier and produces at least one calibration parameter; a detecting device that detects the amplified color signals; a calculation device that calculates at laast one white balance amplification adjustment as a function of the amplified color signals; a comparing device that comparea at L last one white balanee amplification adjustment with at leas: one calibration parameter; and an automatic adjustment isvice that automatically adjusts the white balance amplifier to amplify the aigual level of at least one color signal if at least one white balance amplification adjustment is consistent with at least one calibration parameter. According to another aspect of the preaen: invention, an imaging device is provided which includes an imarihg device for converting an image into a plurality of color signals each having a signal level; a white balance amplifier that adjusts the signal level of at least one color signal to produce a plurality of amplified color signals; a calibration device for repeatedly calibrating the white balance amplifier and for proiicing a plurality of calibration parameters; a detecting device that detects the amplified color signals; a first calculation device that calculates at least one white balance amplification adjustment as a function of the amplified color signals; a storage device that stores the calibration parameters a second calculation device that retrieves the calibration parameters froms the storage means and that calculates an overall calibration factor aa a function of the plurality of calibration parameters; a compering device that compares at lease one white balance amplification adjustment with the overall calibration parameter; and an automatic adjustment device for automatically adjusting the white balanca amplifier to amplify the signal level of at leas one of the color signals if at least one white balance amplification ad;ustment is consistent with the overall calibration parameter. Other objects, features, and advantages according to the present invention will become apparent from th* following detailed description of illustrated embodiments when read in conjunction with the accompanying drawings in which the same components are identified by tha sane reference numerals. BRIF DESCRIPTION OF DRAWINGS Pig. 1 is a block diagram of an image recorder l according to an embodiment of the present invention; Fig. 2 ia flow chart to which reference will be made in describing the operation of an image recorder according to the present invention, Fig. 3 is a menu display siagram; Fig. 4(a) and 4(b) are diagrams of gain values; Fig, 5(a) and 5(b) are mer.u display diagram; Fig. 6 is a diagram of gain values; Pig. 1 is flow chart to which reference will be made in describing another operation of an image recorder according to the present invention/ Fig. 8 ie a flow chart to which reference will be made in describing a step from the flow chart of Pig. 7; Fig. 9 ie a diagram of gain values; Figa. 10(a) and 10(b) are diagrams of gair values; and Figs. 11(a) and ll(b) are diagrams of gair values. DETAILED DESCRIPTION OF THE Figure 1 illustrates an imaging device 100 according bo an embodiment of the present invention. Imaging device 100 includes charge-coupled devices (CCD) 1R, 1G, and IB; preamplifiers 2R, 20, and 2B; i ample/hold gain control circuits 3R, 3G, and 3B; variable rasijtore 4R and 4B; white balance amplifier 5; amplifiers 6R, 60, aid 6B; encoder 7; composite circuit 9/ view finder driver 10, view finder 11, controller 12, character generator 13, memory device 14, digital-to-analog (D/X) converter 15, operation circuit 16; and analog-to-digital (A/D) converter 17. CCD 1R, CCD 1G, and CCD IB are convention*! primary color image pick-up devices for imaging incident red, green, and blue liflht, respectively. CCD 1R. produces a red signal R, CCD lG produces a green signal 3, and CCD 1B produces a blue signal 8 which ara transmitted to raepactive pre-amplifiers IR, 2G, and 2B. Pre-amplifiers 2R, 2G, and 2B are conventional pre-amplifier devices for ampitrying input signals. Pre-amplifiere 2R, 2G, and 2B output amplified R, G, and B signals to respective sample/hold gain control circuits 3R, 3G, and 3B. Sample/hold gain control circuits 3R, ;G, and 3B sample and hold input signals in a conventional manrer and pre-proceee the input image signal*. ?ct example, such pre- processing may include gain control flame processing pre-knee compensation, or the like. Pre-processed R and B eighale from sample/lvold gain control circuits 3R and 3B are supplied to respective variable resistors 4R and 4B. Variable resistors 4R and 4B are variable resistance elements far further adjusting the pre-processed R and B signals, respectively, Variable resistors 4R and B are utilized to adjust Che levels of pre-processed R and 9 signals to achieve a white balance operation. White balance amplifier 5 ie comprised of variable-gain amplifiers 5R and 5B, along with amplifier 5G. Each of variable- gain amplifiers 5X and 53 are conventional variable-gain amplifiers, while amplifier SG ie a |conventional amplifier. variable-gain amplifier 5R amplifier the signal suplied from variable resistor 4R to produce an amplified R signal which is supplied to amplifier SR. Variable-gain amplifier 5B amplifies rh» aion»l supplied from variable r&sistor 4B to prceduse an amplified B signal which is supplied to amplifier 6,1. Amplifier 5G amplifies the pre-processed G signal supplied from sample/hold gain control circuit 2G to produce an amplified G signal which ie suppli«d to amplifier 60, As a practical example, a white balance operation could be achieved by imaging a reference light source, setting the gaine of variable-gain amplifiers 5R and 5B at intermediate values, and then adjusting variable resistors 4R and 4B auch that the outputs of amplifier 5 are equal. However, in the present embodiment, primarily variable-gain amplifiers 5R and 5B are utilised to achieve the white balance operation. Amplifiers 69., 60, and SB are conventional amplifier devices which further amplify the amplified R, G, ard B signals . input respectively thereto, and which output further amplified R, G, and B signals to encoder 7. The amplified R, G, and a signals are also supplied to A/D converter 17. A/D converter 17 ia a conventional analog-to-digital conversion device. A/D converter 17 converts the amplified R, G, and a signals to digital ft, G, and 6 signals, respectively! which are supplied to controller 12. Controller 12 is a conventional controller device, preferably a conventional microprocessor device, which operates to control imaging device 100. Controller 12 is, in turn, responsive to control signals provided by operation circuit 16. Alternatively, operation circuit 16 stores software programs which are accessed by and implemented within controller 12 to direct the operation of controller 12. Operation circuit 16 is preferably a source of control signals. Alternatively, operation eiremit 16 is a memory device which stares aoftware programs lor directing the operation of controller 12. Controller 12 utili2es mamory 14, a conventional data storage device, in performing its control operations. Memory 14 may store parameter data, such as gain control values, for an AWB operation by controller 12, provide temporary data storage for aontroller 12 during computations and other processing, and perform additional similar activities. Encoder 7 is a conventional signal processing and encoding device. Encoder 7 may prodess the further amplified R, -j, ana a ai^ndia output t>y mnyiXCieiH «k, oo, «uia 01: w «v1^«t« gamma correction, toiee correction, and B signal gain adjustments are initially i displayed along with the ATW adjustment operation prompt. in this manner, subsequent AWB operations may be utilised to update stored Radj and Badj values. Preferably, the user's selection of the ATW adjustment operation ia entered via a user interface portion of operation circuit 16. operation circuit 16 transmits the user's selection to controller 12 which initiates the ATW adjustment aperation accordingly. The ATW adjustment operation may be carried out repeatedly by a viser as needed. Figure 2 illustrates an ATW adjustment operation mat hod according to an embodiment of the p. eaenc invention In step PlOl, controller 12 detects the output signal leveli of th« amplified R, a, and B signals via A,'D converter 17, and processing proceeds with step F102. In 6tep F102, controller 12 calculates the gain adjustments, R^f and BMQ(/ r.etdod by variable-amplifiers 5R and 58/ respectively, to equalise the amplified R and S signals with the amplified G signal, and processing proceeds with etep F103, In step F103, an offset fcr the ATW contrd area is calculated by subtracting the ideal intermediate amplification value, e.g. 128 in the present eacaaipla, from each or the stored signal gain adjustments lUdj and Bacj . As an example utilizing sample Radj And 3adj values from Figure 3, fcadj - 131 and Badj > 128, an R gain offset of 3 (=131-121) and a 8 gain offset of 0 (»128-12S> can be calculated, controller ia correcra (shifts) the ATW control area by an amount ecual to the calcilatad R gain offset and B gain offset values. Farther to the absve example, MTTdrrion nt th* ATW control area of Pidure 4 (a) i3 achieved bv shifting the ATW control area by three R gain units ind «erc 8 gain units as shown in Figure 4(b). Of course, the ATW control area may be shifted along the Again axis, the again *xis, or both depending on the calculated offset values. Proeeesiig proceed* with step F1G4. in step F104, the gain ad;ustments, acarn and Bcain, calculated by controller 12 are compared by controller 12 to the corrected ATM control ared. If cither Rain or Bcand :,9 outside the corrected ATW control ares i.e. represent values net included among the eet of values represented by the ATW control area, then controller 12 determines that the present corresponding image is not suitable for use in white balance adjustment, amplifiers 5R and. 5B are not adjusted, and procesing returr.s to step f101 It both Rcw, and Ban are within the corrected ATW control area, i.e. represent values included among the set of values represented by the ATW control area, then controller 12 determines that the present corresponding image is suitable for use in white balance adjufttment and processing proceeds with step F10S. Zn step F105, controller 12 supplier gain control flignala corresponding to fche Rca and Bain, values thnaugh 0/A converter 15 to variable-sfain amplifiers 5R and 5B, reapectively. In this manner white balance is achieved. The whiti balanced signals are amplified by amplifiers 6R, 60, and 6B, encoded by encoder 7, and output at output terminal 8. In an alternate ATW operation, variation .In the reterence lignt source used tor white balance callpation can be accommodated by manual adjustment of the ATW control area. Variation in the reference light source may be measured by a uaer with a color chromaticity system ana the resulting reeasurements converted into corresponding signal gain adjustment values, Radj and Badj for correction (shift) of ;he ATW control area. Figurej 5(a) and 5(b) illustrate in alter-ative ATW operation menu. As in tha menu of *igure 3, the ua^r te displayed a prompt to initiate an ATW adjustment operation ("ATW ADJU) along with the R and B 'ignal gain adjustments calculated by controller 12 in a preceding awb operation. Additionally, the user is prompted to modify, if desired, the displayed R and B signal gain adjustment values, The user enters «» uooAicu raoamt;auiufi via trie user interlace portion ot operation circuit 16. Figure 5(a) hows a user's rmsdification of the R signal gain adjustment value to 13S and Figuri 6(b) shows * user's modification of the B signal gain adjustment value to 130. The modified R and B signal gain adjustments are etc red by controller 12 in memory l* ae gigr.a, gain adjustments Radj and Badj, respectively, e.g. Radj = 135 and Badj 130, Of course, the preceding values are intended to illustrate and not limit the seop« of the present invention. Otherwise, ATW processing proceeds as illtiatrated in Figure 2. utilising the sample modified signal gain adjustment values mentioned above, the ATW control area of Figure 4(a) is correspondingly corrected by shifting the area by sitven R gain units and two B gain units as shown in Figure 6. In a further embodiment of imaging device 100, controller 12 stores multiple aets cf R signal gain idjustment and B signal gain adjustment value* produced by successive implementation of the above-described AWB operation and/or manual adjustment of the A7W control area. For example, R,-dj and Badj values from a previous ten AWB operations may be stcred in memory 14 for selective recall by a ueex. Preferably, sets of R aigr.al gain adjustment and a signal gain adjustment values, Rad; and Badj, are snored in memory 14 as (Rawbll], Bawb[l]), (JUwbl2J, Bawb:2]) .. (KavbtlOl, BawhUO]) in reverse chronological order, where MRcwbfx], Bawb[x])" (x = i, 2/...10) represents a pair of registers, or simply address locations, in memory 14. Preferably, after each AWB operation or manual adjustment of the ATW control are*, tba oldest R signal gain adjustment valve and the oldest B signal gain adjustment value, e.g. the valves stored in (Rs.tfbfiol, BawbClO]), are discarded; each of the remaining pain of values are shifted by one register (address location is incremented); and the new R and & signal gain adjustment values are stored in (Rawb[il, Bawb[i]). in this manner, the reverse chronological order is preserved. A method of ATW processinc with Btorage of multiple eignal gain adjustment values is illustrated in Figure 7. In etep F201, processing is executed asi described above with respect to step F101 but is followed by step F202. in step ?202, i processing is executed as described above with respect to step F102 but is followed by step F203. In step F203 an offset for the ATW control area la calculated as a function of tha distribution of the pairs of Radj and Bad] values stored in memory 14, e.g. (RawbU], Bawb[lJ). (Rawb[3), Bawb[2;) ... (JiawbUO], Bawb[l0]). Thia calculation will be described in further detail here,nbelow. Controller 12 correcta (ahifta) the Ath control area by an amount equal to the calculated R gain offset and B gain offset values. In subsequent atep F204, If either Rmcain or Baainu is outside the corrected ATW control area, i.e. represent values not included among the set of values represented by the ATV control area, then controller 12 determines that the present, corresponding image is not suitable for ue« in white; balance adjustment/ amplifiere 5R and 5B are not adjusted, £-nd processing return* co etep F201. If both Rarem and Bcain, are within the corrected ATW control area, i.e. represent values ir^luded among the set of valuee represented by the ATW control area, then controller 12 determines that the present corresponding image is suitable for uae in white balance adjustment and processing proceeds with step 7205. In step F205, processing is executed as described above with respect to etep F10S but is followed by step F3D1. The offset calculation of step F203 will is described in further detail in connection vrith the flow chart of Figure ft and the diagram of Figure 10(b). Figure 10(b) illus ;rates a portion of the ATW control area shown in Figure 4(a) and shows. specifically, nine pairs of Radj and Bad} value* represented as points S1, S2, S3, S5, S6...S10. For the purposes of. explanation, and not as a limitation on the present invention, it is assumed that memory 14 has stores ten pairs of Rad; and Badj values corresponding to points Si. s2, . . .S10 as follows: S1: (127,127) is stored at (RawbUL 3awb[l]) 32: (129,126) is stored at (RawM2], Jawb(2]) 33: (144,108) is Stored at