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Canon XL1 3CCD Camcorder User Manual

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2.5bpc(oftencalledThousandsofColorsorHighColor)

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The5‐bpccolormodewasusedforsomeveryearlyvideo‐compressioncodecs.Today,itismainly

usedforscreenrecordingapplicationswhereitmayprovidebettercompressionandperformancethan

8‐bpccolorwithoutanyobviousdegradation.

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4.8bpc(alsocalledMillionsorTrueColor)Sometimescalled24‐bitor32‐bitmode.

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The32‐bit

modestilluses8bitsperchannelbutwithanaddedalphachannel.

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5.10bpc

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Thismodeisusedinhigh‐endY’CbCrauthoringsystems(suchasDigitalBetacamandD1)andsome

analogcapturecards.

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Itprovides1024gradationsinsteadof256,whichreducesbanding(uneventransitionsingradated

colors),especiallywithmultiplegenerationsofeffects.

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Itisn’tusedinanydeliveryformats,althoughsomeauthoringcodecssupportit.

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provides4X

moreaccuracyperchannelthan8‐bpccolorwhenconvertingtoorfrom16‐bit‐per‐channelRGBin

AfterEffects.

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6.16and32bpc

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Somehigh‐endapplicationsuse16‐bpcor32‐bpccolourtopreservemorecolourdetail.

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especiallyusefulwhenyouhaveamulti‐stepauthoringprocess,needtoapplyvisualeffectstoyour

images,orwhenyouconvertfromandthenbacktoY’CbCr.

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COLOURSAMPLING

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‐Colorsamplingrecordsfewerpixelsofchroma(color)informationthanluma(intensity)information.

‐TheterminologyforcolorsamplingusesanX:Y:Zformat.X=numberoflumasamplesthatare

described.Y=numberofchromasamplesperlumasampleonthefirst,third,fifth,andsucceedingodd

lines.Z=numberofchromasamplesperlumasampleonthesecond,fourth,sixth,andsucceeding

evenlines.Ifthisnumberiszero,thechromasamplefromthefirstlineisused.

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•4:4:4‐Chromaissampledeverypixelwithnosubsampling.

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Y’CbCrdeliverycodecsdon’tusethisformatbecauseitusesalotofbitsanddoesn’tprovideany

additionalapparentquality.RGBisalways4:4:4.

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