Blending Mode Attribute
| Tag | (0070,1B06) |
|---|---|
| Type | Required (1) |
| Keyword | BlendingMode |
| Value Multiplicity | 1 |
| Value Representation | Code String (CS) |
Describes the method for weighting the different input images during the blending operation:
Enumerated Values:
- EQUAL
-
- FOREGROUND
-
See Section N.2.6 in PS3.4.
Section N.2.6 in PS3.4
N.2.6 Advanced Blending Transformations
The advanced blending transformation model applies to multiple RGB color inputs, and uses foreground blending or equal blending.
Several transformations in this model affect the input prior to its use in blending as depicted in Figure N.2.6-1.
Grayscale inputs that have grayscale transformations (Modality LUT, VOI LUT) and palette color transformations (Palette Color LUT) specified in the Presentation State shall have those transformations applied, as specified in Section N.2.4.2, to produce RGB values.
Grayscale inputs that have no associated Palette Color LUT information specified in the Presentation State or in the reference Image Instance shall be converted to a full color image by setting R equals G equals B.
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.
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.
Figure N.2.6-3. Equal Blending