DICOM PS3.4 2019a - Service Class Specifications

N.2.6 Advanced Blending Transformations

The advanced blending transformation model applies to multiple color inputs and uses foreground blending or equal blending.

Several transformations in this IOD affect the input prior to its use in blending as depicted in Figure N.2.6-1.

Grayscale inputs that have no associated Color LUT information shall have the normal grayscale processing and then be converted to a full color image by setting R equals G equals B.

Color and Threshold Application

Figure N.2.6-1. Color and Threshold Application


Padding pixels in an input are given an opacity value zero and shall be set to 0 for Red, Green, and Blue.

The foreground method blends two inputs. The first input uses an opacity of Relative Opacity (0070,0403) and the second input uses an opacity of (1 - Relative Opacity (0070,0403) ).

If both the inputs are padding values then the result is padding value.

If one of the values is padding value then the result is the non-padding value.

If both pixels have values then result is Relative Opacity * first value + (1 - Relative Opacity) * second value.

Foreground Blending

Figure N.2.6-2. Foreground Blending


The Equal blending mode blends two or more inputs where for each pixel location the opacity is calculated as 1.0 divided by the number of non-padding pixels. The result pixel blends all non-padding pixels using the calculated opacity.

If an input pixel value is the padding-value then the Relative Opacity for that input pixel is zero.

If an input pixel value is not the padding value then the Relative Opacity for that pixel is 1 / (number of input pixels that are non-padding pixels).

The result value is the sum for all input pixels of the input pixel value * Relative Opacity.

If all the inputs pixels are padding values then the result is padding value.

Equal Blending

Figure N.2.6-3. Equal Blending


DICOM PS3.4 2019a - Service Class Specifications