IEEE 201-1979 pdf free.IEEE Standard Definitions of  Terms Relating to Television.
NOTES:(1 ) A footcandle is a unit of incident light，and afootlambert is a unit of emitted or reflected light.Fora perfectly reflecting or perfectly diffusing surface, thenumber of footcandles is equal to the number of footlamberts.(2) The average luminance of any reflecting surfacein footlamberts is，therefore, the product of the illumi-nation in footcandles by the luminous reflectance ofthe surface.
frequency interlace (color television).The ef-fect of intermeshing of the frequency spectrumof a modulated color subcarrier and the har-monics of the horizontal scanning frequencyfor the purpose of minimizing the visibility ofthe modulated color subcarrier.
fusion frequency (television). Frequency ofsuccession of retinal images above which theirdifferences of luminosity or color are no longerperceptible.
NOTE: The fusion frequency is a function of the decaycharacteristic of the display.
gamma (television). The exponent of thatpower law that is used to approximate thecurve of output magnitude versus input magnitude over the region of interest.gamma correction (television).The insertion ofa nonlinear output—input characteristic for thepurpose of changing the system transfer characteristic.geometric distortion (television).The displace-ment of elements in the reproduced picturefrom the correct relative positions in the per-spective plane projection of the original scene.gray scale (television). An optical pattern indiscrete steps between light and dark.
horizontal hold control (television). A syn-chronizing control that adjusts the free-runningperiod of the horizontal deflection oscillator.hue. The attribute of visual sensation desig-nated by blue, green, yellow, red, purple, etc.NOTE: This attribute is the psychosensorial correlate(or nearly so) of the colorimetric quantity dominantwavelength.
chrominance signal (NTSC color television).The sidebands resulting from suppressed-carriermodulation of the chrominance subcarrier bythe I video signal.NOTE: The signal is transmitted in vestigial form, theupper sideband being limited to a frequency withinthe top of the picture transmission channel (approxi-mately 0.6 MHz above the chrominance subcarrier),and the lower sideband extending to approximately 1.5MHz below the subcarrier.The phase of the signal, forpositive I video signals，is 123with respect to the(B一Y ) axis.IEEE 201 pdf download.