Blending modes
Blending modes can be accessed by clicking thisbutton on the main line of a layer, or on the list of its "Mode" parameter.
Rather than simply layering images on top of each other, Autograph has a number of "Blending modes". These modes define the mathematical operations performed at the pixel level where:
- B is the Background
- A is the Forground
- c is the color
- a is the Alpha layer
- Lum is the luminance
- Min is the Minimum
- Max is the Maximum
Some modes in this list add a "Mask Alpha" option, allowing to apply this fusion in a more or less strong way depending on the Alpha channel of A.
Source Atop
Ac * Ba + Bc * (1 - Aa)
The part of the source lying inside of the destination is composited onto the destination
Average
(Ac + Bc) / 2
The average of the 2 images
Color
SetLum(Ac, Lum(Bc))
Creates a color with the hue and saturation of the source color and the luminosity of the backdrop color. This preserves the gray levels of the backdrop and is useful for coloring monochrome images or tinting color images.");
Color Burn
if Ac > 0 1 - min(1, (1 - Bc) / Ac) else 0
Darkens the backdrop color to reflect the source color. Painting with white produces no change.
Color Dodge
if Ac < 1 min(1,Bc / (1 - Ac)) else 1
Brightens the backdrop color to reflect the source color. Painting with black produces no changes.
Conjoint Over
if Aa <= Ba Ac + Bc * (1 - Aa / Da) / b else Ac
Same as the normal over mode, except that when partially covered by both A and B, A hides B
Replace
Ac
Replace the background image by the foreground image
Difference
abs(A - B)
The resultant color is the absolute difference between the source and destination colors
Destination Atop
Bca × Aa + Aca × (1 - Ba)
The part of the destination lying inside of the source is composited over the source and replaces the destination
Disjoint Over
if Aa + Ba >= 1 Ac + Bc * (1 - Aa) / Ba else Ac + Bc
Same as the normal over operation, except that when partially covered by both A and B, the 2 images do not overlap
Divide
if Dc > 0 and Ac > 0 Ac / Bc else 0
Divides the values of the image A by the values of the image B. Stops 2 negative values from becoming a positive value
Exclusion
Ac + Bc - 2 * Ac * Bc
The resultant color is similar to that of the difference operation. However, the exclusion resultant color appears as a lower contrast than that of the difference resultant color.
Subtract
Bc - Ac
Subtract the A image values from the B image values.
Geometric
2 * Ac * Bc / (Ac + Bc)
Similar to average but only where A and B overlap
Grain-Extract
Bc - Ac + 0.5
Extracts grain from image A and adds it ontop of the image B
Grain-Merge
Bc + Ac - 0.5
Merges a grain layer (for example extracted from the Grain-Extract mode) on-top of the B image. This is the opposite of the Grain-extract mode.
Hard-light
if Ac <= 0.5 multiply(Ac) else screen(Ac)
The source color is used to determine if the resultant is either a multiplication or screening of the colors. If the source color is lighter than 0.5, the destination is lightened as if it were screened. If the source color is darker than 0.5, the destination is darkened, as if it were multiplied.
Hue
SetLum(SetSat(Ac, Sat(Bc)), Lum(Bc))
Creates a color with the hue of the source color and the saturation and luminosity of the backdrop color
Hypot
sqrt(Ac * Ac + Bc * Bc)
In-between the Plus and Screen operators
Source In
Ac * Ba
The part of the source lying inside of the destination replaces the destination.
Luminosity
SetLum(Bc, Lum(Ac))
Creates a color with the luminosity of the source color and the hue and saturation of the backdrop color. This produces an inverse effect to that of the Color mode.
Destination In
Bc * Aa
The part of the destination lying inside of the source replaces the destination
Lighten
max(Ac, Bc)
The resultant color is the lighter of source or destination colors. If the source is lighter, it replaces the destination. Otherwise, the destination is preserved.
Darken
min(Ac, Bc)
The resultant color is the darker of source or destination colors. If the source is darker, it replaces the destination. Otherwise, the destination is preserved.
Minus
Ac - Bc
Image B is subtracted from image A
Multiply
if Ac < 0 and Bc < 0 0 else Ac * Bc
Source Out
Ac * (1 - Ba)
The part of the source lying outside of the destination replaces the destination.
Normal
Ac + Bc * (1 - Aa)
The source is composited over the destination"
Overlay
if Bc <= 0.5 2 * Ac * Bc else 1 - 2 * (1 - Bc) * (1 - Sc)"
The destination color is used to determine if the resultant is either a multiplication or screening of the colors. Source colors overlay the destination whilst preserving its highlights and shadows
Pin Light
if B >= 0.5 lighten(Ac, 2 * Bc - 1) else darken(Ac, Bc * 2.0)
A mix of full strength Lighten and Darken blend modes: It completely removes all mid tones
Add
Ac + Dc
The source is added to the destination and replaces the destination. This operator is useful for animating a dissolve between two images
Reflect
Aa * Aa / (1 - Ba)
Darkens the output image using values from the source image
Saturation
SetLum(SetSat(Bc, Sat(Ac)), Lum(Bc))
Creates a color with the saturation of the source color and the hue and luminosity of the backdrop color. Painting with this mode in an area of the backdrop that is a pure gray (no saturation) produces no change.
Screen
Ac + Bc - Ac * Bc
The source and destination colors are complemented, multiplied and the resultant color replaces the destination. The resultant color is always at least as light as either the source or destination colour.
Soft Light
if 2 * Ac <= 1 Bc - (1 - 2 * Ac) * Bc * (1 - Bc) else if 4 * Bc <= 1 Bc + (2 * Ac - 1) * (4 * Bc * (4 * Bc + 1) * (Bc - 1) + 7 * Bc else Bc + (2 * Ac - 1) * (sqrt(Bc) - Bc)
The source colour is used to determine if the resultant color is darkened or lightened. If the source color is lighter than 0.5, the destination is lightened. If the source color is darker than 0.5, the destination is darkened, as if it were burned in. The degree of darkening or lightening is proportional to the difference between the source color and 0.5. If it is equal to 0.5, the destination is unchanged.
Destination Out
Ba * Bc * (1 - Aa)
The part of the destination lying outside of the source replaces the destination
Destination Over
Aa * (1 - Ba) + Bc
The destination is composited over the source and the result replaces the destination
Xor
Ac * (1 - Ba) + Bc * (1 - Aa)
The part of the source that lies outside of the destination is combined with the part of the destination that lies outside of the source.
Linear Light
if Ac < 0. linear-burn(2 * Ac, Bc) else linear-dodge(2 * (Ac - 0.5), Bc)
Use linear-burn to decrease brightness on dark colors and linear-dodge to increase brightness on lighter colors
Linear Dodge
min(Ac + Bc, 1)
Lightens the source image to reflect the destination image color
Linear Burn
Bc + Ac -1
Darkens the source image and reflects the destination image
Vivid Light
if Ac < 0.5 color-burn(2 * Ac, Bc) else color-dodge(2 * (Ac - 0.5), Bc)
A mix of color dodge and Burn. It’s a more intense and saturated contrast mode and can add more saturation to unsaturated images