Now there should be some confusion about all the different transparency information. There are several possibilities to specify the opacity of a pixel:
- solid color opacity (transformation tab, inside tab, outside tab)
- predefined formula variable
alphaand Alpha Channel.
- the Alpha Channel editor
- Coloring by specifying a color (red, green, blue and alpha) in the predefined variable
- layer masks
- ignore alpha setting
First of all, the terms “transparency”, “alpha value” and opacity all mean the same…
Solid Color Opacity
If a pixel is colored using the solid color (because the predefined variable
solid has been set to
true by a formula), then the alpha value of the pixel is specified by the opacity of the solid color. Neither the value of the predefined variable
alpha nor the information from the Alpha Channel editor are considered.
If a formula adjusts the predefined variable
alpha, then the resulting alpha value is multiplied with:
- either the value obtained from the Alpha Channel editor in case the coloring formula used to color the pixel used the predefined variable
- or the alpha part from
pixelcolorin case the coloring formula used to color the pixel used the predefined variable
pixelcolor(direct coloring formula).
Alpha Channel Editor
The alpha gradient will be used for all non-solid pixels which were colored using an indirect coloring formula (i.e. a coloring formula which used the predefined variable
If a pixel was colored using a coloring formula which adjusts the predefined variable
pixelcolor, then the resulting alpha value for that pixel is the alpha part from
pixelcolor multiplied with the value of the predefined variable
alpha. The Alpha Channel editor has no effect, because the pixel was colored using a direct coloring formula.
Ok, these were the methods how a single pixel in a single layer gets its alpha value. If you now switch off the alpha information using the ignore alpha setting, then the resulting alpha value simply will be set to 1.
The next setting is the:
The Factor is a general multiplier for the final alpha value. It does not matter how the alpha value was calculated or what the result is: It will be multiplied with the “Factor” (whose range is from 0% to 100%, i.e. from 0 to 1). So whether the alpha value resulted from the solid color (and its opacity) or from
pixelcolor, it does not matter. Even if you switched off the alpha setting, the final alpha value (which in this special case is 1) will be multiplied with the factor. Mask layers cannot specify the factor, their factor is always 100% (i.e. 1).
If you now declare that a layer should be used as a mask for the layer above (by switching on the Mask-checkbox), then the resulting alpha value from the mask layer will be multiplied with the resulting alpha value from the layer above.
Both alpha values are defined as described above.
And now the last case: If a layer has more than one mask layer assigned to it, then the resulting alpha value from the mask layers is the minimum alpha value of them. This minimum alpha value then gets multiplied with the resulting alpha value from the layer above the mask layers, and then the alpha value gets multiplied with “factor”…
Ok, enough confusion for today! Congratulations if you understood the details above. If not, just play around with the settings, their meaning will be quite intuitive!