Skip to page contents

[ CoalesceImages | DisposeImages | CompareImageLayers | DeconstructImages | OptimizeImageLayers | OptimizeImagePlusLayers ]

CoalesceImages() composites a set of images while respecting any page offsets and disposal methods. GIF, MIFF, and MNG animation sequences typically start with an image background and each subsequent image varies in size and offset. CoalesceImages() returns a new sequence where each image in the sequence is the same size as the first and composited with the next image in the sequence.

The format of the CoalesceImages method is:

  Image *CoalesceImages(Image *image,ExceptionInfo *exception)

A description of each parameter follows:

image

The image sequence.

exception

Return any errors or warnings in this structure.

DisposeImages() returns the coalesced frames of a GIF animation as it would appear after the GIF dispose method of that frame has been applied. That is it returned the appearance of each frame before the next is overlaid.

The format of the DisposeImages method is:

  Image *DisposeImages(Image *image,ExceptionInfo *exception)

A description of each parameter follows:

image

The image sequence.

exception

Return any errors or warnings in this structure.

CompareImageLayers() compares each image with the next in a sequence and returns the minimum bounding region of all the pixel differences (of the LayerType specified) it discovers.

Images do NOT have to be the same size, though it is best that all the images are 'coalesced' (images are all the same size, on a flattened canvas, so as to represent exactly how an specific frame should look).

No GIF dispose methods are applied, so GIF animations must be coalesced before applying this image operator to find differences to them.

The format of the CompareImageLayers method is:

  Image *CompareImageLayers(const Image *images,
    const MagickLayerMethod method,ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

method

The layers type to compare images with. Must be one of... CompareAnyLayer, CompareClearLayer, CompareOverlayLayer.

exception

Return any errors or warnings in this structure.

DeconstructImages() compares each image with the next in a sequence and returns the minimum bounding region of all differences from the first image.

The format of the CompareImageLayers method is:

  Image *DeconstructImages(const Image *images, ExceptionInfo *exception)

A description of each parameter follows:

image

The image.

exception

Return any errors or warnings in this structure.

OptimizeImageLayers() compares each image the GIF disposed forms of the previous image in the sequence. From this it attempts to select the smallest cropped image to replace each frame, while preserving the results of the GIF animation.

The format of the OptimizeImageLayers method is:

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

A description of each parameter follows:

image

The image.

exception

Return any errors or warnings in this structure.

OptimizeImagePlusLayers() is exactly as OptimizeImageLayers(), but may also add or even remove extra frames in the animation, if it improves the total number of pixels in the resulting GIF animation.

The format of the OptimizePlusImageLayers method is:

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

A description of each parameter follows:

image

The image.

exception

Return any errors or warnings in this structure.