Process History - Basic Steps to Apply a Filter with Blend Mode, Opacity, and Image Mask

The Process History window tracks each stretch, smooth, sharpen, deconvolution, and color adjustment filter that is applied to an image. Each filter applied to an image creates a filtered image layer that has its own blend mode, opacity, and mask specified on the Process History window. Blend mode and opacity of a filtered image layer define how the layer is blended with the previous image layer. A mask selects and blends different areas from the filtered image layer and previous image layer. Lighter mask areas select more of the current filter image layer while darker mask areas select more of the previous image layer.

To assign a mask to a filter first apply the filter to an image to enable Blend Mode, Opacity, and the Mask button on the Process History window. Press the Mask button on Process History to display the Mask Surface window with the default all white control point mask already enabled. If a control point mask is best suited for processing then just use the mouse to manipulate the red control points. To use an image mask first create and save the image mask then right click on the mask surface and select Paste. The image mask is assigned to the current image layer and the display updated.




Step 1) Open the Image & Process History Window


When an image is first opened Blend Mode, Opacity, and Mask are disabled on the Process History window since it takes two image layers to use these functions. The Read operation shown in the Operation list of Process History is the initial image layer. A filter is applied to create a second image layer and enable Blend Mode, Opacity, and Mask options. The mask along with blend mode and opacity define how the previous read layer is combined with the current filter layer to create the current image displayed.





Step 2) Create The Image Mask


The image mask used with a filter is usually created from the image before the filter is applied since the goal is to control areas where the filter is applied. To create a luminance mask use the Luminance Mask button second from the top on the left vertical toolbar. The Luminance Mask button will create a single channel gray scale image from either a color or monochrome image. The luminance mask image can then be saved with a descriptive name as a mask.



To name and save the luminance mask use the Save As Then Copy Mask button or top button on the left vertical toolbar. After the image mask is saved it can be assigned to a filter in the Process History layer list.





Step 3) Apply Filter to Image then Assign Image Mask


Apply any stretch, smooth, sharpen, deconvolution, or color adjustment filter to the intital image. In this case Smooth Sharpen | Sharpening & Texture Enhancement | Adaptive Contrast is appiled to sharpen the image. Note that Adaptive Contrast is added to the Operation list of the Process History window and all pixels of the image are sharpened by the same amount. Blend Mode is set to Normal and Opacity is set 100%. The Mask button is enabled with the default all white reveal all control point mask set. The initial read image layer is totally replaced by the Adaptive Contrast sharpened image layer when the default normal blend mode, 100% opacity, and all white reveal all mask are used. After a filter is applied to an image blend mode and opacity can be modified to blend the previous read image layer with the current Adaptive Contrast filter layer. A mask is used to weight the blending of the Adaptive Contrast layer with the previous read layer pixel by pixel. Whiter mask areas weight the Adaptive Contrast filter pixel more than darker mask areas which weight the previous image layer pixel more. The next step shows how to assign an image mask to a filter.




To assign the image mask created and saved in step 2) above press the Mask button on the Process History Window to display the Mask Surface window then right click on the mask surface and select Paste. The image mask is assigned to the current Adaptive Contrast image layer and the display updated.



The luminance mask is assigned to the Adaptive Contrast layer. Lighter mask areas of the image will be sharpened more than darker mask areas. Many different types of image masks can be created and assign to a filter.





Step 4) Modify Blend Mode, Opacity, Mask, and Filter Parameters


Blend mode can be modified to change contrast or color. The mask defines which parts of the current and previous layer are blended. Opacity perform a weighted average of the masked blend mode with the previous image layer. Opacity and blend mode are modified using the controls on the Process History window. To modify the mask press the Mask button on Process History to display the Mask Surface window. Press the Display Mask button on the Mask Surface window to display the mask image. Apply any filter to the mask image to modify the mask.



In this case Stretch | Micro Curves is used to apply an S curve to make the whiter mask areas brighter and darker mask areas darker. The modified mask will increase Adaptive Contrast sharpening of the image where the mask is lighter and decrease sharpening of the image where the mask is darker.



Use the Save button on the top horizontal toolbar to save the modified image mask. Since the image mask was displayed using the Display Mask button on the Mask Surface window the modified image mask is already assigned to Adaptive Contrast sharpening.



After the modified image mask is saved press the Apply button on Mask Surface or Adaptive Contrast to display the image using the updated mask.




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