The base class is used for filters, which can not do direct manipulations with source image. To make effect of in-place filtering, these filters create a background copy of the original image (done by this base class) and then do manipulations with it putting result back to the original source image.

Note:The background copy of the source image is created only in the case of in-place filtering. Otherwise background copy is not created - source image is processed and result is put to destination image.

The base class is for those filters, which support as filtering entire image, as partial filtering of specified rectangle only.