Chatgpt-4
What are the equations for photoshop layer blend modes?
Photoshop's layer blend modes are used to determine how two layers are blended together to produce the final result. Below are some common blend modes with their corresponding equations. In these equations, A represents the top layer's pixel value, B represents the bottom layer's pixel value, and R is the resulting pixel value. All pixel values are in the range [0, 1], where 0 is black and 1 is white.
1.Normal: R = A
2.Multiply: R = A * B
3.Screen: R = 1 - (1 - A) * (1 - B)
4.Overlay:
5.If B <= 0.5: R = 2 * A * B
6.Else: R = 1 - 2 * (1 - A) * (1 - B)
7.Soft Light:
8.If A <= 0.5: R = B + (2 * A - 1) * (B - B^2)
9.Else: R = B + (2 * A - 1) * (sqrt(B) - B)
10.Hard Light:
11.If A <= 0.5: R = 2 * A * B
12.Else: R = 1 - 2 * (1 - A) * (1 - B)
13.Difference: R = abs(A - B)
14.Exclusion: R = A + B - 2 * A * B
15.Linear Burn: R = max(A + B - 1, 0)
16.Linear Dodge (Add): R = min(A + B, 1)
17.Color Burn: R = 1 - min((1 - B) / A, 1)
18.Color Dodge: R = min(B / (1 - A), 1)
19.Darken: R = min(A, B)
20.Lighten: R = max(A, B)
Please note that these equations describe the blend modes for a single color channel. In practice, they are applied independently to each color channel (R, G, and B) in the image. Additionally, Photoshop has other blend modes such as Hue, Saturation, Color, and Luminosity, which require more complex processing involving converting the pixel values to different color spaces (e.g., HSL or LAB) before blending.
Please list any other layer blend modes that are not listed above.
Certainly, here are some additional Photoshop layer blend modes that were not listed in the previous response:
15.Hue:
16.This blend mode keeps the hue of the top layer while adopting the luminance and saturation of the bottom layer. To use this mode, you need to convert the color values to a color space like HSL or HSV, perform the blending, and then convert back to the RGB color space.
17.Saturation:
18.This blend mode keeps the saturation of the top layer while adopting the hue and luminance of the bottom layer. Similar to the Hue blend mode, this also requires conversion to HSL or HSV.
19.Color:
20.This blend mode keeps the hue and saturation of the top layer while adopting the luminance of the bottom layer. It also involves color space conversion to HSL or HSV.
21.Luminosity:
22.This blend mode keeps the luminance of the top layer while adopting the hue and saturation of the bottom layer. Like other color-based blend modes, it requires conversion to HSL or HSV.
23.Vivid Light:
24.This blend mode combines the characteristics of Color Burn and Color Dodge. It uses the following equations:
25.If A <= 0.5: R = 1 - min((1 - B) / (2 * A), 1)
26.Else: R = min(B / (2 * (1 - A)), 1)
27.Linear Light:
28.This blend mode is similar to Linear Burn and Linear Dodge. It uses the following equation:
29.R = 2 * A + B - 1
30.Pin Light:
31.This blend mode is a combination of Darken and Lighten. It uses the following equation:
32.If A <= 0.5: R = min(A * 2, B)
33.Else: R = max(A * 2 - 1, B)
34.Hard Mix:
35.This blend mode uses the following equation:
36.R = (A + B > 1) ? 1 : 0
37.This blend mode is applied to each color channel independently, resulting in a limited color palette.
38.Divide:
39.This blend mode uses the following equation:
40.R = B / (A + 1e-6)
41.The small value (1e-6) is added to prevent division by zero.
42.Subtract:
43.This blend mode uses the following equation:
44.R = max(B - A, 0)
45.Lighter Color:
46.This blend mode compares the two layers' color values and keeps the lighter one in the result.
47.Darker Color:
48.This blend mode compares the two layers' color values and keeps the darker one in the result.
Remember that for most blend modes, the equations are applied independently to each color channel (R, G, and B). However, color-based blend modes (Hue, Saturation, Color, and Luminosity) require conversion to a different color space like HSL or HSV.
How does the dissolve blend mode fit in?
The Dissolve blend mode is different from the other blend modes in that it doesn't rely on a mathematical equation to blend the layers. Instead, it uses a random dithering pattern to blend the layers based on their opacity. This mode can create a grainy, speckled appearance in the resulting image, which may be useful for certain artistic effects or textures.
When using the Dissolve blend mode, the top layer's opacity determines the percentage of its pixels that will be visible in the resulting image. For example, if the top layer's opacity is set to 50%, roughly half of its pixels will be visible, while the other half will be replaced by the corresponding pixels from the bottom layer. The specific pixels that are shown or hidden are chosen randomly, creating the characteristic dithered effect.
It's important to note that the Dissolve blend mode does not produce smooth transitions between layers, unlike most other blend modes. It is best used for special effects or when a grainy, textured appearance is desired.
Please list the brush blending modes.
Brush blending modes in Adobe Photoshop determine how the paint being applied interacts with the existing colors on the canvas or layer. These blending modes are similar to the layer blending modes and often share the same names and equations. Here's a list of brush blending modes available in Photoshop:
1.Normal
2.Dissolve
3.Behind (available only when using the Brush tool)
4.Clear (available only when using the Eraser tool)
5.Darken
6.Multiply
7.Color Burn
8.Linear Burn
9.Darker Color
10.Lighten
11.Screen
12.Color Dodge
13.Linear Dodge (Add)
14.Lighter Color
15.Overlay
16.Soft Light
17.Hard Light
18.Vivid Light
19.Linear Light
20.Pin Light
21.Hard Mix
22.Difference
23.Exclusion
24.Subtract
25.Divide
26.Hue
27.Saturation
28.Color
29.Luminosity
The brush blending modes apply to tools like the Brush, Pencil, and Eraser. The specific behavior of these modes when used with a brush is determined by the opacity and flow settings of the brush, as well as the blending equation corresponding to the selected blending mode.
Keep in mind that this list reflects the brush blending modes available in Adobe Photoshop up to my knowledge cutoff in September 2021. It is possible that new blending modes have been added or that other image editing software may have different brush blending modes.
