Here are the data structures with brief descriptions:

NMagick
CadaptiveBlurImage
CadaptiveThresholdImage
CaddNoiseImage
CadjoinImage
CaffineTransformImage
CalphaFlagImage
CalphaImage
CanimationDelayImage
CanimationIterationsImage
CannotateImage
CbackgroundColorImage
CbackgroundTextureImage
CBlob
CBlobRef
CblurImage
CborderColorImage
CborderImage
CboxColorImage
CcdlImage
CchannelImage
CChannelMoments
CChannelPerceptualHash
CChannelStatistics
CcharcoalImage
CchopImage
CchromaBluePrimaryImage
CchromaGreenPrimaryImage
CchromaRedPrimaryImage
CchromaWhitePointImage
CCoderInfo
CColor
CColorCMYK
CcolorFuzzImage
CColorGray
CColorHSL
CcolorizeImage
CcolorMapImage
CcolorMatrixImage
CColorMono
CColorRGB
CcolorSpaceImage
CColorYUV
CcommentImage
CcomposeImage
CcompositeImage
CcompressTypeImage
CcontrastImage
CCoordinate
CcropImage
CcycleColormapImage
CdensityImage
CdepthImage
CdespeckleImage
CdistortImage
CDrawable
CDrawableAffine
CDrawableAlpha
CDrawableArc
CDrawableBase
CDrawableBezier
CDrawableBorderColor
CDrawableCircle
CDrawableClipPath
CDrawableClipRule
CDrawableClipUnits
CDrawableColor
CDrawableCompositeImage
CDrawableDensity
CDrawableEllipse
CDrawableFillColor
CDrawableFillOpacity
CDrawableFillPatternUrl
CDrawableFillRule
CDrawableFont
CDrawableGravity
CDrawableLine
CDrawableMiterLimit
CDrawablePath
CDrawablePoint
CDrawablePointSize
CDrawablePolygon
CDrawablePolyline
CDrawablePopClipPath
CDrawablePopGraphicContext
CDrawablePopPattern
CDrawablePushClipPath
CDrawablePushGraphicContext
CDrawablePushPattern
CDrawableRectangle
CDrawableRotation
CDrawableRoundRectangle
CDrawableScaling
CDrawableSkewX
CDrawableSkewY
CDrawableStrokeAntialias
CDrawableStrokeColor
CDrawableStrokeDashArray
CDrawableStrokeDashOffset
CDrawableStrokeLineCap
CDrawableStrokeLineJoin
CDrawableStrokeOpacity
CDrawableStrokePatternUrl
CDrawableStrokeWidth
CDrawableText
CDrawableTextAlignment
CDrawableTextAntialias
CDrawableTextDecoration
CDrawableTextDirection
CDrawableTextInterlineSpacing
CDrawableTextInterwordSpacing
CDrawableTextKerning
CDrawableTextUnderColor
CDrawableTranslation
CDrawableViewbox
CdrawImage
CedgeImage
CembossImage
CendianImage
CenhanceImage
CequalizeImage
CError
CErrorBlob
CErrorCache
CErrorCoder
CErrorConfigure
CErrorCorruptImage
CErrorDelegate
CErrorDraw
CErrorFileOpen
CErrorImage
CErrorMissingDelegate
CErrorModule
CErrorMonitor
CErrorOption
CErrorPolicy
CErrorRegistry
CErrorResourceLimit
CErrorStream
CErrorType
CErrorUndefined
CErrorXServer
CException
CfileNameImage
CfillColorImage
CfilterTypeImage
CflipImage
CfloodFillAlphaImage
CfloodFillColorImage
CfloodFillTextureImage
CflopImage
CfontImage
CfontPointsizeImage
CframeImage
CgammaImage
CgaussianBlurImage
CGeometry
CgifDisposeMethodImage
ChaldClutImage
CImage
CImageMoments
CImagePerceptualHash
CImageRef
CImageStatistics
CimplodeImage
CinterlaceTypeImage
CinverseFourierTransformImage
CisValidImage
ClabelImage
ClevelImage
CmagickImage
CMagickPlusPlusGenesis
CmagnifyImage
CmapImage
CmatteColorImage
CmedianConvolveImage
CmergeLayersImage
CminifyImage
CmodulateImage
CmonochromeImage
CMontage
CMontageFramed
CMutexLock
CnegateImage
CnormalizeImage
COffset
CoilPaintImage
CopaqueImage
COptions
CpageImage
CPathArcAbs
CPathArcArgs
CPathArcRel
CPathClosePath
CPathCurvetoAbs
CPathCurvetoArgs
CPathCurvetoRel
CPathLinetoAbs
CPathLinetoHorizontalAbs
CPathLinetoHorizontalRel
CPathLinetoRel
CPathLinetoVerticalAbs
CPathLinetoVerticalRel
CPathMovetoAbs
CPathMovetoRel
CPathQuadraticCurvetoAbs
CPathQuadraticCurvetoArgs
CPathQuadraticCurvetoRel
CPathSmoothCurvetoAbs
CPathSmoothCurvetoRel
CPathSmoothQuadraticCurvetoAbs
CPathSmoothQuadraticCurvetoRel
CpenColorImage
CpenTextureImage
CpixelColorImage
CPixelData
CPixels
CPoint
CqualityImage
CquantizeColorsImage
CquantizeColorSpaceImage
CquantizeDitherImage
CquantizeImage
CquantizeTreeDepthImage
CraiseImage
CReadOptions
CreduceNoiseImage
CrenderingIntentImage
CresizeImage
CresolutionUnitsImage
CResourceLimits
CrollImage
CrotateImage
CsampleImage
CscaleImage
CsceneImage
CSecurityPolicy
CsegmentImage
CshadeImage
CshadowImage
CsharpenImage
CshaveImage
CshearImage
CsigmoidalContrastImage
CsizeImage
CsolarizeImage
CspliceImage
CspreadImage
CsteganoImage
CstereoImage
CstripImage
CstrokeColorImage
CsubImageImage
CsubRangeImage
CswirlImage
CtextAntiAliasImage
CtextureImage
CthresholdImage
CtransparentImage
CtrimImage
CtypeImage
CTypeMetric
CverboseImage
CVPath
CVPathBase
CWarning
CWarningBlob
CWarningCache
CWarningCoder
CWarningConfigure
CWarningCorruptImage
CWarningDelegate
CWarningDraw
CWarningFileOpen
CWarningImage
CWarningMissingDelegate
CWarningModule
CWarningMonitor
CWarningOption
CWarningPolicy
CWarningRegistry
CWarningResourceLimit
CWarningStream
CWarningType
CWarningUndefined
CWarningXServer
CwaveImage
Cx11DisplayImage
CzoomImage
CmyBlob