MLUnsold Digital Imaging

Process History Blend Modes & Opacity

The Process History window in ImagesPlus is used to assign a blend mode and opacity to an operation. Blend mode and opacity define how the image created by the current operation is combined or blended with the image created by the previous operation. First the current and previous image are combined using the blend mode to create a blend mode image. Opacity is applied to mix the blend mode image with the previous image to create the current image.

Blend Modes

Normal - Default mode - The current image is used and hides the previous image 100%.
Darken - Selects the minimum or darkest pixel from the current and previous image.
Multiply - White is unchanged and no part of the image gets lighter. Darkens the previous image directly based on the darkness of the current image.
Color Burn - Burns in the color of the current image with the previous image. No part of the current image will get lighter.
Linear Burn - Similar to color burn but the results are more intense.
Lighten - Selects the maximum or lightest pixel from the current and previous image.
Screen - Screen brightens by lightning the previous image based on the lightness of the current image. The result is always lighter.
Color Dodge - Similar to screen but with more intense results.
Linear Dodge - Similar to color dodge but with more intense results.
Overlay - Multiplies light areas and screens dark areas. Similar to an S-curve or contrast increase.
Soft Light - Muliplies the dark areas and screens the light areas. Softer S-curve or contrast increase.
Hard Light - Muliplies the dark areas and screens the light areas. Stronger S-curve or contrast increase.
Vivid Light - Dodge or burn the previous image depending on whether the current image pixels are brighter or darker than neutral gray. Similar to hard light but with more intense results.
Linear Light - Similar to vivid light but with more intense results.
Pin Light - Multiply when the current image is darker than neutral gray otherwise use screen.
Hard Mix - Similar to linear light but with more intense results.
Reflect - Has the appearance of reflecting the current image off of the previous image.
Glow - Has the appearance of reflecting the previous image off of the current image.
Add - Add the current and previous image.
Average - Average the current and previous image.
Subtract - Subtracts the current image from the previous image.
Difference - Subtract the current image from the previous image then uses the absolute value. Large difference is lighter than small difference.
Exclusion - Previous image masks the difference between the current and previous image.
Negation - White minus the absolute value of white minus current and previous image.
Hue - Select hue from the current image. Saturation and luminance are selected from the previous image.
Saturation - Select Saturation from the current image. Hue and luminance are selected from the previous image.
Color - Select hue and saturation from the current image. Luminance is selected from the previous image.
Luminosity - Select luminance from the current image. Hue and saturation are selected from the previous image.

Opacity

Opacity is used to mix the previous image with the image created by the current operation with blend mode.
The mix is defined as [current image] = (1.0 - opacity) * [previous image] + opacity * [current operation with blend mode image] where 0 <= opacity <= 1.0.
If opacity is 1.0 then the current operation with blend mode image is shown 100%.
If opacity is 0.0 then the previous image is shown 100%.
If opacity is between 0.0 and 1.0 then the current image shown is the weighted average of the previous image and the current operation with blend mode image.

Initial image on left. Center image has a mild increase micro curve applied with screen blend mode and opacity = 1.0 set on the Process History window to boost brightness. Opacity = 1.0 allows the micro curve screen blend to show at 100%.

Image on right has opacity = 0.516 which mixes the previous and micro curve screen image. The mix is given by [current image] = (1.0 - opacity) * [previous image] + opacity * [micro curve screen image] which is very near an average of the two images.

Initial image on left. Center image has a mild increase micro curve applied with screen blend mode and opacity = 1.0 set on the Process History window to boost brightness. Opacity = 1.0 allows the micro curve screen blend to show at 100%.

Image on right has opacity = 0.516 which mixes the previous and micro curve screen image. The mix is given by [current image] = (1.0 - opacity) * [previous image] + opacity * [micro curve screen image] which is very near an average of the two images.