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[ MagnifyImage | MinifyImage | ResizeImage | SampleImage | ScaleImage | ThumbnailImage | ZoomImage ]

MagnifyImage() is a convenience method that scales an image proportionally to twice its size.

The format of the MagnifyImage method is:

  Image *MagnifyImage(const Image *image,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

exception

Return any errors or warnings in this structure.

MinifyImage() is a convenience method that scales an image proportionally to half its size.

The format of the MinifyImage method is:

  Image *MinifyImage(const Image *image,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

exception

Return any errors or warnings in this structure.

ResizeImage() scales an image to the desired dimensions with one of these filters:

      Bessel   Blackman   Box
      Catrom   CubicGaussian
      Hanning  Hermite    Lanczos
      Mitchell PointQuandratic
      Sinc     Triangle

Most of the filters are FIR (finite impulse response), however, Bessel, Gaussian, and Sinc are IIR (infinite impulse response). Bessel and Sinc are windowed (brought down to zero) with the Blackman filter.

ResizeImage() was inspired by Paul Heckbert's zoom program.

The format of the ResizeImage method is:

  Image *ResizeImage(Image *image,const unsigned long columns,
    const unsigned long rows,const FilterTypes filter,const double blur,
    ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

columns

The number of columns in the scaled image.

rows

The number of rows in the scaled image.

filter

Image filter to use.

blur

The blur factor where > 1 is blurry, < 1 is sharp.

exception

Return any errors or warnings in this structure.

SampleImage() scales an image to the desired dimensions with pixel sampling. Unlike other scaling methods, this method does not introduce any additional color into the scaled image.

The format of the SampleImage method is:

  Image *SampleImage(const Image *image,const unsigned long columns,
    const unsigned long rows,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

columns

The number of columns in the sampled image.

rows

The number of rows in the sampled image.

exception

Return any errors or warnings in this structure.

ScaleImage() changes the size of an image to the given dimensions.

The format of the ScaleImage method is:

  Image *ScaleImage(const Image *image,const unsigned long columns,
    const unsigned long rows,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

columns

The number of columns in the scaled image.

rows

The number of rows in the scaled image.

exception

Return any errors or warnings in this structure.

ThumbnailImage() changes the size of an image to the given dimensions and removes any associated profiles. The goal is to produce small low cost thumbnail images suited for display on the Web.

The format of the ThumbnailImage method is:

  Image *ThumbnailImage(const Image *image,const unsigned long columns,
    const unsigned long rows,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

columns

The number of columns in the scaled image.

rows

The number of rows in the scaled image.

exception

Return any errors or warnings in this structure.

ZoomImage() creates a new image that is a scaled size of an existing one. It allocates the memory necessary for the new Image structure and returns a pointer to the new image. The Point filter gives fast pixel replication, Triangle is equivalent to bi-linear interpolation, and Mitchel giver slower, very high-quality results. See Graphic Gems III for details on this algorithm.

The filter member of the Image structure specifies which image filter to use. Blur specifies the blur factor where > 1 is blurry, < 1 is sharp.

The format of the ZoomImage method is:

  Image *ZoomImage(const Image *image,const unsigned long columns,
    const unsigned long rows,ExceptionInfo *exception)

A description of each parameter follows:

zoom_image

Method ZoomImage returns a pointer to the image after scaling. A null image is returned if there is a memory shortage.

image

The image.

columns

An integer that specifies the number of columns in the zoom image.

rows

An integer that specifies the number of rows in the scaled image.

exception

Return any errors or warnings in this structure.