CHAPTER 7
522
Transparency
NAME
RESULT
HardLight
Multiplies or screens the colors, depending on the source color value. The effect is similar
to shining a harsh spotlight on the backdrop.
⎧
Multiply
(
c
b
,
2
×
c
s
)
B
(
c
b
,
c
s
)
=
⎨
⎩
Screen
(
c
b
,
2
×
c
s
–
1
)
SoftLight
if
c
s
≤
0.5
if
c
s
>
0.5
Darkens or lightens the colors, depending on the source color value. The effect is similar
to shining a diffused spotlight on the backdrop.
⎧
c
b
–
(
1
–
2
×
c
s
) ×
c
b
× (
1
–
c
b
)
B
(
c
b
,
c
s
) =
⎨
⎩
c
b
+
(
2
×
c
s
–
1
) × (
D
(
c
b
) –
c
b
)
where
if
c
s
≤
0.5
if
c
s
>
0.5
⎧
( (
16
×
x
–
12
) ×
x
+
4
) ×
x
D
(
x
) =
⎨
⎩
x
Difference
if
x
≤
0.25
if
x
>
0.25
Subtracts the darker of the two constituent colors from the lighter color:
B
(
c
b
,
c
s
) =
c
b
–
c
s
Painting with white inverts the backdrop color; painting with black produces no change.
Exclusion
Produces an effect similar to that of the
Difference
mode but lower in contrast. Painting
with white inverts the backdrop color; painting with black produces no change.
B
(
c
b
,
c
s
) =
c
b
+
c
s
–
2
×
c
b
×
c
s
blend modes consider all color components in combination, their computation
depends on the blending color space in which the components are interpreted.
They may be applied to all multiple-component color spaces that are allowed as
blending color spaces (see Section 7.2.3, “Blending Color Space”).
All of these blend modes conceptually entail the following steps:
1. Convert the backdrop and source colors from the blending color space to an
intermediate
HSL
(hue-saturation-luminosity) representation.
2. Create a new color from some combination of hue, saturation, and luminosity
components selected from the backdrop and source colors.