Editing Selected Areas- Part II
  by Dennis Wilkins


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Picture Window and Picture Window Pro provide two functions that enable combining images, or parts of images. These are the Composite transformation and Stack Images transformation. In some cases, you can choose one or the other method to obtain the same result, but other situations will require choosing only one. The Stack Images tool is new to Picture Window Pro 3.5 and provides combining two or more images (up to five at once) based on Density Masks (these use a form of brightness curve control) and Amount Masks (like used with the Rocky Mountain creek image to control the intensity of the effect or totally mask off parts of an image).

The Stack Images tool is intended to combine two otherwise identical images that have different brightness ranges, such as two different exposures captured with a digital camera, one capturing shadow detail but “burning out” highlights, the other capturing the highlights. It can also be used for creative “graphic-arts” effects to blend images.

The Composite transformation is a general purpose image combining tool that includes Amount Masks to isolate what area of an image is used, but does not have Density Masks. On the other hand, the Composite transformation has very flexible Alignment capabilities that enables shifting the position of one image relative to the other. In fact there are six different alignment methods in addition to “none” (“none” simply combines the two images directly over one another, aligned at the lower left corner if the Overlay image is smaller than the Input image).

The image below was captured in the Rocky Mountains above Vail, Colorado, and suffers from overexposed clouds and compressed tones in what were very bright Aspen leaves. Digital cameras and slide film have limited dynamic range and often force you to either overexpose bright areas or underexpose the darker areas of an image.

masking step 1