1、1. scope 3. Format This guideline specifies the purpose, format, and usage of a television picture monitor alignment color bar test signal with chroma set and black set signais. 3.1 Fig. 1 shows the appearance of the EIA Standard RS-189-.4, Encoded Color Bar Signal, on a picture monitor. Fig. 2 show
2、s the appearance of the align- ment color bar test signal on a picture monitor. Note that Fig. 2, the Alignment Color Bar Test Signal, is tlie same as Fig. 1 except for the addition of chroma set simal X-Xl and black set sianal 2. Purpose v 2.1 2.2 2.3 The alignment color bar test signal is intended
3、 to standardize the adjustment of chroma gain, chroma phase, and black level monitor coiitrols. Chroma gain and chroma phase for picture moni- tors are conventionally adjusted by observing the standard encoded color bar signal (see Fig. 1) with red and green monitor guns switched off. The four visib
4、le blue bars are adjusted for equal bright- ness. This procedure is prone to error because of the subjective judgment necessary and especially because the blue bars are widely separated on the screen. The use of the chroma set signal portion of the alignment color bar test signal greatly in- creases
5、 the accuracy of this adjustment since it provides a signal with the blue bars to be matched vertically adjacent to each other. Because the bars are adjacent, the eye can easily perceive any dif- ference in brightness. It also eliminates effects due to shading or purity from one part of the monitor
6、to another. Black level for picture monitors is conveniently adjusted by observing a known black portion of the signal and matching it to a blanked area of the signal. This procedure is prone to error because of the subjective judgment necessary to make the match. The use of the black set signal por
7、tion of the alignment color bar test signal greatly in- creases the accuracy of this adjustment since it prmides ;i positive go-on-go criterion for the proper setting. It also minimizes errors due to variations in ambient light. VI (within Y-Yi). 3.2 The chroma set signal is a small band of bars dis
8、 played in place of the bottom portion of nomal color bars. The bars are displayed in reverse order. Only the four bars which contain blue are neces- sary; the remaining three bars may be black. Fig. 3 shows the appearance of one line of the chroma set signal on a waveform monitor. 3.3 The black se
9、t signal is located in the bottom right- hand portion of the raster. Two bars, one slightly whiter-than-black and the other slightly blacker- than-black, are included. Fig. 4 shows the appear- ance of one line of the black set signal on a wave- form monitor. 4. Usage 4.1 To set chroma gain and phase
10、 the picture monitor red and green guns are switched off. Chroma gain is adjusted by matching the brightness of the outer left or right main blue bar with the chroma set bar just below. In a similar manner, chroma phase is adjusted by matching the brightness of either cen- ter main blue bar with th
11、e chroma set bar just below. 4.2 To set black level, the picture monitor brightness control is adjusted so that the whiter-than-black bar is visible with respect to the black surround but the blacker-than-black bar is not visible. SMPTE EG*L 90 U 8357403 0000025 942 B31 WH I TE +a Page 2 of 3 pages
12、EG 1-1390 b b b b b r YELLOW l- GRAY CY AN GREEN I MAGENTA BLUE RED BLACK 7 5% 100% -I L - Fig. 1 EIA Standard RS-189-A, Encoded Color Bar Signal c GREEN GRAY YELLOW MAGENTA CYAN MAGENTA I RED BLUE o- o BLUE BLACK BLACK BLACK CYAN BLACU GRAY BLACK l- -r WH I TE Ll-l-l 5/4b f 5/4b i 5/4b 5/4b b = 1/7
13、 ACTIVE LINE TIME Fig. 2 Alignment Color Bar Test Signal 100 - no - 80 - 70 - 80 - 50 - 40 - 30 - 20 - 10 - 100 - eo - 80 - 70 - 80 - 50 - 40 - 30 - 20 - IO - 0- -10 - -20 - ao - -40 - SMPTE EG*3 90 111 8357403 0000026 889 Page 3 of 3 pages EG 1-1990 r -2 o B -20 -5 Fir. 3 - One Line of Chroma Set Signal, X-Xi I RE SCALE UNITS + 100 - +27.5 + 27.5 +11.5 -1 + 20 -2 o -12.5 Fia. 4 -2 o -INDICATES LUHIHANCE VALUES - One Line of Black Set Signal with -I, +Q, and White Reference, Y-YI
