|Extension TIFF Tag ImageLayer|
TIFF Tag Reference
TIFF Tag ImageLayer
Defined in the Mixed Raster Content part of RFC 2301, used to denote the particular function of this Image in the mixed raster scheme.
Image layers are defined such that layer 1 is the Background layer, layer 3 is the Foreground layer, and layer 2 is the Mask layer, which selects pixels from the Background and Foreground layers. The ImageLayer tag contains two values, describing the layer to which the image belongs and the order in which it is imaged.
ImageLayer = 1, 2, 3.
ImageLayer describes the image order. In MRC, this may be considered the strip number. Since MRC mode currently does not allow overlap between images within a layer, the order value does not have any visual effect.