MLUnsold Digital Imaging

Process History Control Point & Image Masks

ImagesPlus has two ways to generate masks. Image masks are created by applying an operation to an image such as luminance to create a luminance mask. Control point masks are synthetic masks genereated by moving points similar to moving points to define a curve used by a standard Curves or Micro Curves tool.

General Mask Properties

A mask is a grayscale image that defines how two images are blended together to make a single image.
Unlike blending modes and opacity which apply the same fixed blend to each pixel a mask can apply a variable blend.
The mask blend is given by [masked image] = [previous image] * (1.0 - Mask) + Mask * [current image] where mask values range from 0.0 for black to 1.0 for white.
White mask areas select the same area from the current image 100%.
Black mask areas select the same area from the previous image 100%.
Gray mask areas blend the current and previous image based on the gray value at each pixel.
A mask in ImagesPlus is always a single channel grayscale image with the same width and height as the current and previous image.
A control point mask is a synthetic mask generated by moving points in 3 dimensions to define the grayscale mask similar to moving points in 2 dimensions to define a curve used by a standard Curves tool.

Control Point Mask Properties

Control point masks are created using the Mask Surface tool which is displayed using the Mask button on the Process History window.
The default control point mask is all white and will select the current operation image 100%.
The control point mask can be set to a constant black or gray level using the Mask Level slider on the Mask Surface tool.
Left-click and hold on one of the red mask control points to move it up and down. This changes the z-coordinate of the control point and makes the mask lighter or darker.
Hold Shift and Left-click on one of the red mask control points to move in x-coordinate or y-coordinate direction and make the mask lighter or darker.
Control points can be moved as separate points or as a group. Use the Mask Control Point Groups list on the Mask Surface Tool to select separate or groups of points.
Preset control point masks are shown by the Preset Mask list on the Mask Surface tool.
Use the Load and Save buttons on Mask Surface to save control point masks to a hard drive or load a control point mask to a different operation or image.
Copy a control point mask to different operations or images. Right-click on the control point mask on the Mask Surface window then select Copy. Right-click on the control point mask on the Mask Surface window of a diffenent image operation and select Paste.
Use the Display button on the Mask Surface tool to display a control point mask as an image mask. The image mask can be modified and used as an image mask as described in the Image Mask Properties section below.
Note : Since control point mask are generated the same mask can be used with any image size. The control point mask is automatically sized to match the image.

Control point masked used to restrict application of Micro Curves to just the top right corner of the image on right. Original image shown on left with dark top left and right corners caused by vignetting.

Control point masked used to consentrate application of Additive Color Balance red and blue increase to the center of the image. Soft light blend mode is set on the Process History window to increse contrast. Opacity = 0.714 blends 71.4% of the masked soft light Additive Color Balance image with 28.6% of the image before Additive color Balance was applied.

Image Mask Properties

Image masks are grayscale images the same width and height as the image they are applied to.
Image masks are assigned to an operation applied to an image using the Mask button on the Process History window.
Copy a grayscale image as an image mask. Left-click on a grayscale image then use the Save As Then Copy Mask toolbar button to name and copy the image mask. Right-click on the mask area in the Mask Surface tool of an operation and select Paste.
Copy an image mask from one operation to another. Right-click on the image mask on the Mask Surface window and select Copy. Right-click on the mask area on the Mask Surface window of a diffenent image operation and select Paste.
Use the Display button on the Mask Surface tool to display the image mask. The image mask can be modified using any of the image process tools then saved or copied as an image mask.
Common image mask creation tools in ImagesPlus include Selective Color Mask, High Pass Filter, Threshold, Gaussian Blur, LRGB Luminance, Custom Luminance, Edge, Area, and Local Painting. Many different image masks can be created using these tool including star, inverse luminance, edge, difference, exclusion, background, object, and high pass masks.
Note : Image masks are always the same wide and height as the current image they are applied to.

Inverse luminance threshold mask restricts smoothing to the background.

Luminance threshold mask restricts deconvolution to M1 and stars.

Selective color mask isolates green. Hue tool rotates green toward red.

Control point masked used to restrict application of Micro Curves to just the top right corner of the image on right. Original image shown on left with dark top left and right corners caused by vignetting.

Inverse luminance threshold mask restricts smoothing to the background.

Luminance threshold mask restricts deconvolution to M1 and stars.

Selective color mask isolates green. Hue tool rotates green toward red.