Commit message: https://github.com/ImageMagick/ImageMagick/issues/1724
CVE: CVE-2020-25663
CWE: CWE-416
Vulnerability description: A call to ConformPixelInfo() in the SetImageAlphaChannel() routine of /MagickCore/channel.c caused a subsequent heap-use-after-free or heap-buffer-overflow READ when GetPixelRed() or GetPixelBlue() was called. This could occur if an attacker is able to submit a malicious image file to be processed by ImageMagick and could lead to denial of service. It likely would not lead to anything further because the memory is used as pixel data and not e.g. a function pointer. This flaw affects ImageMagick versions prior to 7.0.9-0.

Project: ImageMagick
File: channel.c

static inline void FlattenPixelInfo(const Image *image,const PixelInfo *p,
  const double alpha,const Quantum *q,const double beta,
  Quantum *composite)
{
  double
    Da,
    gamma,
    Sa;

  register ssize_t
    i;

  /*
    Compose pixel p over pixel q with the given alpha.
  */
  Sa=QuantumScale*alpha;
  Da=QuantumScale*beta,
  gamma=Sa*(-Da)+Sa+Da;
  gamma=PerceptibleReciprocal(gamma);
  for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
  {
    PixelChannel channel = GetPixelChannelChannel(image,i);
    PixelTrait traits = GetPixelChannelTraits(image,channel);
    if (traits == UndefinedPixelTrait)
      continue;
    switch (channel)
    {
      case RedPixelChannel:
      {
        composite[i]=ClampToQuantum(gamma*MagickOver_((double) q[i],beta,
          (double) p->red,alpha));
        break;
      }
      case GreenPixelChannel:
      {
        composite[i]=ClampToQuantum(gamma*MagickOver_((double) q[i],beta,
          (double) p->green,alpha));
        break;
      }
      case BluePixelChannel:
      {
        composite[i]=ClampToQuantum(gamma*MagickOver_((double) q[i],beta,
          (double) p->blue,alpha));
        break;
      }
      case BlackPixelChannel:
      {
        composite[i]=ClampToQuantum(gamma*MagickOver_((double) q[i],beta,
          (double) p->black,alpha));
        break;
      }
      case AlphaPixelChannel:
      {
        composite[i]=ClampToQuantum(QuantumRange*(Sa*(-Da)+Sa+Da));
        break;
      }
      default:
        break;
    }
  }
}

Project: ImageMagick
File: channel.c

MagickExport Image *CombineImages(const Image *image,
  const ColorspaceType colorspace,ExceptionInfo *exception)
{
#define CombineImageTag  "Combine/Image"

  CacheView
    *combine_view;

  Image
    *combine_image;

  MagickBooleanType
    status;

  MagickOffsetType
    progress;

  ssize_t
    y;

  /*
    Ensure the image are the same size.
  */
  assert(image != (const Image *) NULL);
  assert(image->signature == MagickCoreSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickCoreSignature);
  combine_image=CloneImage(image,0,0,MagickTrue,exception);
  if (combine_image == (Image *) NULL)
    return((Image *) NULL);
  if (SetImageStorageClass(combine_image,DirectClass,exception) == MagickFalse)
    {
      combine_image=DestroyImage(combine_image);
      return((Image *) NULL);
    }
  if (colorspace != UndefinedColorspace)
    (void) SetImageColorspace(combine_image,colorspace,exception);
  else
    if (fabs(image->gamma-1.0) <= MagickEpsilon)
      (void) SetImageColorspace(combine_image,RGBColorspace,exception);
    else
      (void) SetImageColorspace(combine_image,sRGBColorspace,exception);
  switch (combine_image->colorspace)
  {
    case UndefinedColorspace:
    case sRGBColorspace:
    {
      if (GetImageListLength(image) > 3)
        combine_image->alpha_trait=BlendPixelTrait;
      break;
    }
    case LinearGRAYColorspace:
    case GRAYColorspace:
    {
      if (GetImageListLength(image) > 1)
        combine_image->alpha_trait=BlendPixelTrait;
      break;
    }
    case CMYKColorspace:
    {
      if (GetImageListLength(image) > 4)
        combine_image->alpha_trait=BlendPixelTrait;
      break;
    }
    default:
      break;
  }
  /*
    Combine images.
  */
  status=MagickTrue;
  progress=0;
  combine_view=AcquireAuthenticCacheView(combine_image,exception);
  for (y=0; y < (ssize_t) combine_image->rows; y++)
  {
    CacheView
      *image_view;

    const Image
      *next;

    Quantum
      *pixels;

    register const Quantum
      *magick_restrict p;

    register Quantum
      *magick_restrict q;

    register ssize_t
      i;

    if (status == MagickFalse)
      continue;
    pixels=GetCacheViewAuthenticPixels(combine_view,0,y,combine_image->columns,
      1,exception);
    if (pixels == (Quantum *) NULL)
      {
        status=MagickFalse;
        continue;
      }
    next=image;
    for (i=0; i < (ssize_t) GetPixelChannels(combine_image); i++)
    {
      register ssize_t
        x;

      PixelChannel channel = GetPixelChannelChannel(combine_image,i);
      PixelTrait traits = GetPixelChannelTraits(combine_image,channel);
      if (traits == UndefinedPixelTrait)
        continue;
      if (next == (Image *) NULL)
        continue;
      image_view=AcquireVirtualCacheView(next,exception);
      p=GetCacheViewVirtualPixels(image_view,0,y,next->columns,1,exception);
      if (p == (const Quantum *) NULL)
        continue;
      q=pixels;
      for (x=0; x < (ssize_t) combine_image->columns; x++)
      {
        if (x < (ssize_t) next->columns)
          {
            q[i]=GetPixelGray(next,p);
            p+=GetPixelChannels(next);
          }
        q+=GetPixelChannels(combine_image);
      }
      image_view=DestroyCacheView(image_view);
      next=GetNextImageInList(next);
    }
    if (SyncCacheViewAuthenticPixels(combine_view,exception) == MagickFalse)
      status=MagickFalse;
    if (image->progress_monitor != (MagickProgressMonitor) NULL)
      {
        MagickBooleanType
          proceed;

#if defined(MAGICKCORE_OPENMP_SUPPORT)
        #pragma omp atomic
#endif
        progress++;
        proceed=SetImageProgress(image,CombineImageTag,progress,
          combine_image->rows);
        if (proceed == MagickFalse)
          status=MagickFalse;
      }
  }
  combine_view=DestroyCacheView(combine_view);
  if (status == MagickFalse)
    combine_image=DestroyImage(combine_image);
  return(combine_image);
}

Project: ImageMagick
File: channel.c

MagickExport Image *ChannelFxImage(const Image *image,const char *expression,
  ExceptionInfo *exception)
{
#define ChannelFxImageTag  "ChannelFx/Image"

  ChannelFx
    channel_op;

  ChannelType
    channel_mask;

  char
    token[MagickPathExtent];

  const char
    *p;

  const Image
    *source_image;

  double
    pixel;

  Image
    *destination_image;

  MagickBooleanType
    status;

  PixelChannel
    source_channel,
    destination_channel;

  ssize_t
    channels;

  assert(image != (Image *) NULL);
  assert(image->signature == MagickCoreSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickCoreSignature);
  source_image=image;
  destination_image=CloneImage(source_image,0,0,MagickTrue,exception);
  if (destination_image == (Image *) NULL)
    return((Image *) NULL);
  if (expression == (const char *) NULL)
    return(destination_image);
  status=SetImageStorageClass(destination_image,DirectClass,exception);
  if (status == MagickFalse)
    {
      destination_image=GetLastImageInList(destination_image);
      return((Image *) NULL);
    }
  destination_channel=RedPixelChannel;
  channel_mask=UndefinedChannel;
  pixel=0.0;
  p=(char *) expression;
  (void) GetNextToken(p,&p,MagickPathExtent,token);
  channel_op=ExtractChannelOp;
  for (channels=0; *token != '\0'; )
  {
    ssize_t
      i;

    /*
      Interpret channel expression.
    */
    switch (*token)
    {
      case ',':
      {
        (void) GetNextToken(p,&p,MagickPathExtent,token);
        break;
      }
      case '|':
      {
        if (GetNextImageInList(source_image) != (Image *) NULL)
          source_image=GetNextImageInList(source_image);
        else
          source_image=GetFirstImageInList(source_image);
        (void) GetNextToken(p,&p,MagickPathExtent,token);
        break;
      }
      case ';':
      {
        Image
          *canvas;

        (void) SetPixelChannelMask(destination_image,channel_mask);
        if ((channel_op == ExtractChannelOp) && (channels == 1))
          {
            (void) SetPixelMetaChannels(destination_image,0,exception);
            (void) SetImageColorspace(destination_image,GRAYColorspace,
              exception);
          }
        canvas=CloneImage(source_image,0,0,MagickTrue,exception);
        if (canvas == (Image *) NULL)
          {
            destination_image=DestroyImageList(destination_image);
            return(destination_image);
          }
        AppendImageToList(&destination_image,canvas);
        destination_image=GetLastImageInList(destination_image);
        status=SetImageStorageClass(destination_image,DirectClass,exception);
        if (status == MagickFalse)
          {
            destination_image=GetLastImageInList(destination_image);
            return((Image *) NULL);
          }
        (void) GetNextToken(p,&p,MagickPathExtent,token);
        channels=0;
        destination_channel=RedPixelChannel;
        channel_mask=UndefinedChannel;
        break;
      }
      default:
        break;
    }
    i=ParsePixelChannelOption(token);
    if (i < 0)
      {
        (void) ThrowMagickException(exception,GetMagickModule(),OptionError,
          "UnrecognizedChannelType","`%s'",token);
        destination_image=DestroyImageList(destination_image);
        return(destination_image);
      }
    source_channel=(PixelChannel) i;
    channel_op=ExtractChannelOp;
    (void) GetNextToken(p,&p,MagickPathExtent,token);
    if (*token == '<')
      {
        channel_op=ExchangeChannelOp;
        (void) GetNextToken(p,&p,MagickPathExtent,token);
      }
    if (*token == '=')
      {
        if (channel_op != ExchangeChannelOp)
          channel_op=AssignChannelOp;
        (void) GetNextToken(p,&p,MagickPathExtent,token);
      }
    if (*token == '>')
      {
        if (channel_op != ExchangeChannelOp)
          channel_op=TransferChannelOp;
        (void) GetNextToken(p,&p,MagickPathExtent,token);
      }
    switch (channel_op)
    {
      case AssignChannelOp:
      case ExchangeChannelOp:
      case TransferChannelOp:
      {
        if (channel_op == AssignChannelOp)
          pixel=StringToDoubleInterval(token,(double) QuantumRange+1.0);
        else
          {
            i=ParsePixelChannelOption(token);
            if (i < 0)
              {
                (void) ThrowMagickException(exception,GetMagickModule(),
                  OptionError,"UnrecognizedChannelType","`%s'",token);
                destination_image=DestroyImageList(destination_image);
                return(destination_image);
              }
          }
        destination_channel=(PixelChannel) i;
        if (i >= (ssize_t) GetPixelChannels(destination_image))
          (void) SetPixelMetaChannels(destination_image,(size_t) (
            destination_channel-GetPixelChannels(destination_image)+1),
            exception);
        if (image->colorspace != UndefinedColorspace)
          switch (destination_channel)
          {
            case RedPixelChannel:
            case GreenPixelChannel:
            case BluePixelChannel:
            case BlackPixelChannel:
            case IndexPixelChannel:
              break;
            case AlphaPixelChannel:
            {
              destination_image->alpha_trait=BlendPixelTrait;
              break;
            }
            case CompositeMaskPixelChannel:
            {
              destination_image->channels=(ChannelType)
                (destination_image->channels | CompositeMaskChannel);
              break;
            }
            case ReadMaskPixelChannel:
            {
              destination_image->channels=(ChannelType)
                (destination_image->channels | ReadMaskChannel);
              break;
            }
            case WriteMaskPixelChannel:
            {
              destination_image->channels=(ChannelType)
                (destination_image->channels | WriteMaskChannel);
              break;
            }
            case MetaPixelChannel:
            default:
            {
              (void) SetPixelMetaChannels(destination_image,(size_t) (
                destination_channel-GetPixelChannels(destination_image)+1),
                exception);
              break;
            }
          }
        channel_mask=(ChannelType) (channel_mask | ParseChannelOption(token));
        if (((channels >= 1)  || (destination_channel >= 1)) &&
            (IsGrayColorspace(destination_image->colorspace) != MagickFalse))
          (void) SetImageColorspace(destination_image,sRGBColorspace,exception);
        (void) GetNextToken(p,&p,MagickPathExtent,token);
        break;
      }
      default:
        break;
    }
    status=ChannelImage(destination_image,destination_channel,channel_op,
      source_image,source_channel,ClampToQuantum(pixel),exception);
    if (status == MagickFalse)
      {
        destination_image=DestroyImageList(destination_image);
        break;
      }
    channels++;
    if (channel_op == ExchangeChannelOp)
      {
        status=ChannelImage(destination_image,source_channel,channel_op,
          source_image,destination_channel,ClampToQuantum(pixel),exception);
        if (status == MagickFalse)
          {
            destination_image=DestroyImageList(destination_image);
            break;
          }
        channels++;
      }
    switch (channel_op)
    {
      case ExtractChannelOp:
      {
        channel_mask=(ChannelType) (channel_mask |
          (1UL << destination_channel));
        destination_channel=(PixelChannel) (destination_channel+1);
        break;
      }
      default:
        break;
    }
    status=SetImageProgress(source_image,ChannelFxImageTag,p-expression,
      strlen(expression));
    if (status == MagickFalse)
      break;
  }
  (void) SetPixelChannelMask(destination_image,channel_mask);
  if ((channel_op == ExtractChannelOp) && (channels == 1))
    {
      (void) SetPixelMetaChannels(destination_image,0,exception);
      (void) SetImageColorspace(destination_image,GRAYColorspace,exception);
    }
  return(GetFirstImageInList(destination_image));
}

Project: ImageMagick
File: channel.c

static MagickBooleanType ChannelImage(Image *destination_image,
  const PixelChannel destination_channel,const ChannelFx channel_op,
  const Image *source_image,const PixelChannel source_channel,
  const Quantum pixel,ExceptionInfo *exception)
{
  CacheView
    *source_view,
    *destination_view;

  MagickBooleanType
    status;

  size_t
    height,
    width;

  ssize_t
    y;

  status=MagickTrue;
  source_view=AcquireVirtualCacheView(source_image,exception);
  destination_view=AcquireAuthenticCacheView(destination_image,exception);
  height=MagickMin(source_image->rows,destination_image->rows);
  width=MagickMin(source_image->columns,destination_image->columns);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
  #pragma omp parallel for schedule(static) shared(status) \
    magick_number_threads(source_image,source_image,height,1)
#endif
  for (y=0; y < (ssize_t) height; y++)
  {
    PixelTrait
      destination_traits,
      source_traits;

    register const Quantum
      *magick_restrict p;

    register Quantum
      *magick_restrict q;

    register ssize_t
      x;

    if (status == MagickFalse)
      continue;
    p=GetCacheViewVirtualPixels(source_view,0,y,source_image->columns,1,
      exception);
    q=GetCacheViewAuthenticPixels(destination_view,0,y,
      destination_image->columns,1,exception);
    if ((p == (const Quantum *) NULL) || (q == (Quantum *) NULL))
      {
        status=MagickFalse;
        continue;
      }
    destination_traits=GetPixelChannelTraits(destination_image,
      destination_channel);
    source_traits=GetPixelChannelTraits(source_image,source_channel);
    if ((destination_traits == UndefinedPixelTrait) ||
        (source_traits == UndefinedPixelTrait))
      continue;
    for (x=0; x < (ssize_t) width; x++)
    {
      if (channel_op == AssignChannelOp)
        SetPixelChannel(destination_image,destination_channel,pixel,q);
      else
        SetPixelChannel(destination_image,destination_channel,
          GetPixelChannel(source_image,source_channel,p),q);
      p+=GetPixelChannels(source_image);
      q+=GetPixelChannels(destination_image);
    }
    if (SyncCacheViewAuthenticPixels(destination_view,exception) == MagickFalse)
      status=MagickFalse;
  }
  destination_view=DestroyCacheView(destination_view);
  source_view=DestroyCacheView(source_view);
  return(status);
}

Project: ImageMagick
File: channel.c

MagickExport MagickBooleanType GetImageAlphaChannel(const Image *image)
{
  assert(image != (const Image *) NULL);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(image->signature == MagickCoreSignature);
  return(image->alpha_trait != UndefinedPixelTrait ? MagickTrue : MagickFalse);
}

Project: ImageMagick
File: channel.c

MagickExport Image *SeparateImages(const Image *image,ExceptionInfo *exception)
{
  Image
    *images,
    *separate_image;

  register ssize_t
    i;

  assert(image != (Image *) NULL);
  assert(image->signature == MagickCoreSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  images=NewImageList();
  for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
  {
    PixelChannel channel = GetPixelChannelChannel(image,i);
    PixelTrait traits = GetPixelChannelTraits(image,channel);
    if ((traits == UndefinedPixelTrait) || ((traits & UpdatePixelTrait) == 0))
      continue;
    separate_image=SeparateImage(image,(ChannelType) (1UL << channel),
      exception);
    if (separate_image != (Image *) NULL)
      AppendImageToList(&images,separate_image);
  }
  if (images == (Image *) NULL)
    images=SeparateImage(image,UndefinedChannel,exception);
  return(images);
}

Project: ImageMagick
File: channel.c

MagickExport Image *SeparateImage(const Image *image,
  const ChannelType channel_type,ExceptionInfo *exception)
{
#define GetChannelBit(mask,bit)  (((size_t) (mask) >> (size_t) (bit)) & 0x01)
#define SeparateImageTag  "Separate/Image"

  CacheView
    *image_view,
    *separate_view;

  Image
    *separate_image;

  MagickBooleanType
    status;

  MagickOffsetType
    progress;

  ssize_t
    y;

  /*
    Initialize separate image attributes.
  */
  assert(image != (Image *) NULL);
  assert(image->signature == MagickCoreSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickCoreSignature);
  separate_image=CloneImage(image,0,0,MagickTrue,exception);
  if (separate_image == (Image *) NULL)
    return((Image *) NULL);
  if (SetImageStorageClass(separate_image,DirectClass,exception) == MagickFalse)
    {
      separate_image=DestroyImage(separate_image);
      return((Image *) NULL);
    }
  separate_image->alpha_trait=UndefinedPixelTrait;
  (void) SetImageColorspace(separate_image,GRAYColorspace,exception);
  separate_image->gamma=image->gamma;
  /*
    Separate image.
  */
  status=MagickTrue;
  progress=0;
  image_view=AcquireVirtualCacheView(image,exception);
  separate_view=AcquireAuthenticCacheView(separate_image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
  #pragma omp parallel for schedule(static) shared(progress,status) \
    magick_number_threads(image,image,image->rows,1)
#endif
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    register const Quantum
      *magick_restrict p;

    register Quantum
      *magick_restrict q;

    register ssize_t
      x;

    if (status == MagickFalse)
      continue;
    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
    q=QueueCacheViewAuthenticPixels(separate_view,0,y,separate_image->columns,1,
      exception);
    if ((p == (const Quantum *) NULL) || (q == (Quantum *) NULL))
      {
        status=MagickFalse;
        continue;
      }
    for (x=0; x < (ssize_t) image->columns; x++)
    {
      register ssize_t
        i;

      SetPixelChannel(separate_image,GrayPixelChannel,(Quantum) 0,q);
      for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
      {
        PixelChannel channel = GetPixelChannelChannel(image,i);
        PixelTrait traits = GetPixelChannelTraits(image,channel);
        if ((traits == UndefinedPixelTrait) ||
            (GetChannelBit(channel_type,channel) == 0))
          continue;
        SetPixelChannel(separate_image,GrayPixelChannel,p[i],q);
      }
      p+=GetPixelChannels(image);
      q+=GetPixelChannels(separate_image);
    }
    if (SyncCacheViewAuthenticPixels(separate_view,exception) == MagickFalse)
      status=MagickFalse;
    if (image->progress_monitor != (MagickProgressMonitor) NULL)
      {
        MagickBooleanType
          proceed;

#if defined(MAGICKCORE_OPENMP_SUPPORT)
        #pragma omp atomic
#endif
        progress++;
        proceed=SetImageProgress(image,SeparateImageTag,progress,image->rows);
        if (proceed == MagickFalse)
          status=MagickFalse;
      }
  }
  separate_view=DestroyCacheView(separate_view);
  image_view=DestroyCacheView(image_view);
  (void) SetImageChannelMask(separate_image,DefaultChannels);
  if (status == MagickFalse)
    separate_image=DestroyImage(separate_image);
  return(separate_image);
}

Project: ImageMagick
File: channel.c

MagickExport MagickBooleanType SetImageAlphaChannel(Image *image,
  const AlphaChannelOption alpha_type,ExceptionInfo *exception)
{
  CacheView
    *image_view;

  MagickBooleanType
    status;

  ssize_t
    y;

  assert(image != (Image *) NULL);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(image->signature == MagickCoreSignature);
  status=MagickTrue;
  switch (alpha_type)
  {
    case ActivateAlphaChannel:
    {
      image->alpha_trait=BlendPixelTrait;
      break;
    }
    case AssociateAlphaChannel:
    {
      /*
        Associate alpha.
      */
      status=SetImageStorageClass(image,DirectClass,exception);
      if (status == MagickFalse)
        break;
      image_view=AcquireAuthenticCacheView(image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
      #pragma omp parallel for schedule(static) shared(status) \
        magick_number_threads(image,image,image->rows,1)
#endif
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        register Quantum
          *magick_restrict q;

        register ssize_t
          x;

        if (status == MagickFalse)
          continue;
        q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
          exception);
        if (q == (Quantum *) NULL)
          {
            status=MagickFalse;
            continue;
          }
        for (x=0; x < (ssize_t) image->columns; x++)
        {
          double
            gamma;

          register ssize_t
            i;

          gamma=QuantumScale*GetPixelAlpha(image,q);
          for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
          {
            PixelChannel channel = GetPixelChannelChannel(image,i);
            PixelTrait traits = GetPixelChannelTraits(image,channel);
            if (channel == AlphaPixelChannel)
              continue;
            if ((traits & UpdatePixelTrait) == 0)
              continue;
            q[i]=ClampToQuantum(gamma*q[i]);
          }
          q+=GetPixelChannels(image);
        }
        if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
          status=MagickFalse;
      }
      image_view=DestroyCacheView(image_view);
      image->alpha_trait=CopyPixelTrait;
      return(status);
    }
    case BackgroundAlphaChannel:
    {
      /*
        Set transparent pixels to background color.
      */
      if (image->alpha_trait == UndefinedPixelTrait)
        break;
      status=SetImageStorageClass(image,DirectClass,exception);
      if (status == MagickFalse)
        break;
      image_view=AcquireAuthenticCacheView(image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
      #pragma omp parallel for schedule(static) shared(status) \
        magick_number_threads(image,image,image->rows,1)
#endif
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        register Quantum
          *magick_restrict q;

        register ssize_t
          x;

        if (status == MagickFalse)
          continue;
        q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
          exception);
        if (q == (Quantum *) NULL)
          {
            status=MagickFalse;
            continue;
          }
        for (x=0; x < (ssize_t) image->columns; x++)
        {
          if (GetPixelAlpha(image,q) == TransparentAlpha)
            {
              SetPixelViaPixelInfo(image,&image->background_color,q);
              SetPixelChannel(image,AlphaPixelChannel,TransparentAlpha,q);
            }
          q+=GetPixelChannels(image);
        }
        if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
          status=MagickFalse;
      }
      image_view=DestroyCacheView(image_view);
      return(status);
    }
    case CopyAlphaChannel:
    {
      image->alpha_trait=UpdatePixelTrait;
      status=CompositeImage(image,image,IntensityCompositeOp,MagickTrue,0,0,
        exception);
      break;
    }
    case DeactivateAlphaChannel:
    {
      if (image->alpha_trait == UndefinedPixelTrait)
        status=SetImageAlpha(image,OpaqueAlpha,exception);
      image->alpha_trait=CopyPixelTrait;
      break;
    }
    case DisassociateAlphaChannel:
    {
      /*
        Disassociate alpha.
      */
      status=SetImageStorageClass(image,DirectClass,exception);
      if (status == MagickFalse)
        break;
      image->alpha_trait=BlendPixelTrait;
      image_view=AcquireAuthenticCacheView(image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
      #pragma omp parallel for schedule(static) shared(status) \
        magick_number_threads(image,image,image->rows,1)
#endif
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        register Quantum
          *magick_restrict q;

        register ssize_t
          x;

        if (status == MagickFalse)
          continue;
        q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
          exception);
        if (q == (Quantum *) NULL)
          {
            status=MagickFalse;
            continue;
          }
        for (x=0; x < (ssize_t) image->columns; x++)
        {
          double
            gamma,
            Sa;

          register ssize_t
            i;

          Sa=QuantumScale*GetPixelAlpha(image,q);
          gamma=PerceptibleReciprocal(Sa);
          for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
          {
            PixelChannel channel = GetPixelChannelChannel(image,i);
            PixelTrait traits = GetPixelChannelTraits(image,channel);
            if (channel == AlphaPixelChannel)
              continue;
            if ((traits & UpdatePixelTrait) == 0)
              continue;
            q[i]=ClampToQuantum(gamma*q[i]);
          }
          q+=GetPixelChannels(image);
        }
        if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
          status=MagickFalse;
      }
      image_view=DestroyCacheView(image_view);
      image->alpha_trait=UndefinedPixelTrait;
      return(status);
    }
    case DiscreteAlphaChannel:
    {
      if (image->alpha_trait == UndefinedPixelTrait)
        status=SetImageAlpha(image,OpaqueAlpha,exception);
      image->alpha_trait=UpdatePixelTrait;
      break;
    }
    case ExtractAlphaChannel:
    {
      status=CompositeImage(image,image,AlphaCompositeOp,MagickTrue,0,0,
        exception);
      image->alpha_trait=UndefinedPixelTrait;
      break;
    }
    case OffAlphaChannel:
    {
      image->alpha_trait=UndefinedPixelTrait;
      break;
    }
    case OnAlphaChannel:
    {
      if (image->alpha_trait == UndefinedPixelTrait)
        status=SetImageAlpha(image,OpaqueAlpha,exception);
      image->alpha_trait=BlendPixelTrait;
      break;
    }
    case OpaqueAlphaChannel:
    {
      status=SetImageAlpha(image,OpaqueAlpha,exception);
      break;
    }
    case RemoveAlphaChannel:
    {
      /*
        Remove transparency.
      */
      if (image->alpha_trait == UndefinedPixelTrait)
        break;
      status=SetImageStorageClass(image,DirectClass,exception);
      if (status == MagickFalse)
        break;
      image_view=AcquireAuthenticCacheView(image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
      #pragma omp parallel for schedule(static) shared(status) \
        magick_number_threads(image,image,image->rows,1)
#endif
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        register Quantum
          *magick_restrict q;

        register ssize_t
          x;

        if (status == MagickFalse)
          continue;
        q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
          exception);
        if (q == (Quantum *) NULL)
          {
            status=MagickFalse;
            continue;
          }
        for (x=0; x < (ssize_t) image->columns; x++)
        {
          FlattenPixelInfo(image,&image->background_color,
            image->background_color.alpha,q,(double) GetPixelAlpha(image,q),q);
          q+=GetPixelChannels(image);
        }
        if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
          status=MagickFalse;
      }
      image_view=DestroyCacheView(image_view);
      image->alpha_trait=image->background_color.alpha_trait;
      break;
    }
    case SetAlphaChannel:
    {
      if (image->alpha_trait == UndefinedPixelTrait)
        status=SetImageAlpha(image,OpaqueAlpha,exception);
      break;
    }
    case ShapeAlphaChannel:
    {
      /*
        Remove transparency.
      */
      image->alpha_trait=BlendPixelTrait;
      status=SetImageStorageClass(image,DirectClass,exception);
      if (status == MagickFalse)
        break;
      image_view=AcquireAuthenticCacheView(image,exception);
#if defined(MAGICKCORE_OPENMP_SUPPORT)
      #pragma omp parallel for schedule(static) shared(status) \
        magick_number_threads(image,image,image->rows,1)
#endif
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        PixelInfo
          background;

        register Quantum
          *magick_restrict q;

        register ssize_t
          x;

        if (status == MagickFalse)
          continue;
        ConformPixelInfo(image,&image->background_color,&background,exception);
        q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
          exception);
        if (q == (Quantum *) NULL)
          {
            status=MagickFalse;
            continue;
          }
        background.alpha_trait=BlendPixelTrait;
        for (x=0; x < (ssize_t) image->columns; x++)
        {
          background.alpha=GetPixelIntensity(image,q);
          SetPixelViaPixelInfo(image,&background,q);
          q+=GetPixelChannels(image);
        }
        if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
          status=MagickFalse;
      }
      image_view=DestroyCacheView(image_view);
      break;
    }
    case TransparentAlphaChannel:
    {
      status=SetImageAlpha(image,TransparentAlpha,exception);
      break;
    }
    case UndefinedAlphaChannel:
      break;
  }
  if (status == MagickFalse)
    return(status);
  (void) SetPixelChannelMask(image,image->channel_mask);
  return(SyncImagePixelCache(image,exception));
}