Image Stack

Command:

Tools > Image Stack

The Image Stack can be used to superimpose images on top of photos and combine these images in various ways ("image fusion"). In order to be able to exactly superimpose photos with calculated images, one has first to load and calibrate the photo(s), or to create an artificial "photo" which is rendered as a gray-scale contour map displaying the integral of the available spectra.

The current image stack may be stored on disk and reloaded later-on for presentation purposes. Please note that loading a stored image stack requires the same data file to be loaded as when the image stack has been stored. Loading the image stack anyway might cause problems (either a missing background photo or a mismatch of the scaled layers).

How To:

Whenever you want to copy an image to the Image Stack, right-click the image and select "Copy to Image Stack" from the context menu, or click the "copy to image stack" button , if available. Adjust the blending weight an blending mode to fit your needs Hint: You can adjust the default settings for the blending mode and the blending level in the Preferences dialog.

Hint:

The Image Stack is a window which can be moved outside the Epina ImageLab main window in order to facilitate the parallel display of the image stack and the main window (which is especially usefull with multi-monitor systems).

Combination	Explanation
Add	Adds the background image B and the layer L; the intensities of both B and L are scaled by the factor w [0..100]. Each color component (red, green, blue) is added separately and the results are clipped to avoid overflow effects: result := (w*L+(100-w)*B)/100
Difference	Computes the absolute difference the background image B and the layer L. the intensity of the layer L can be scaled by the factor w [0..100]: result := abs(B-L*w/100)
Exclusion	The resulting image is formed by adding the background and the foreground image and subtracting the properly scaled product of the background and foreground image. The foreground image is scaled by the factor w [0..100]: result := B + F*w/100 - F*w/100*B/128
Max	Calculates the maximum of the background image B and the layer L; the intensity of the layer L can be scaled by the factor w [0..100]: result := max(B,w*L/100)
Min	Calculates the minimum of the background image B and the layer L; the intensity of the layer L can be scaled by the factor w [0..100]: result := min(B,w*L/100)
Multiply	Multiplies background image B and the layer L; the intensity of the layer L can be scaled by the factor w [0..100]: result := B*L*w/100
Opaque	The layer L is opaque, all layers below L are hidden.
Sub	Subtracts the layer L from the background image B; the intensities of L can be scaled by the factor w [0..100]. Each color component (red, green, blue) is subtracted separately and the results are clipped to avoid underflow effects: result := B-w*L/100
WhiteMix	Mixes the background image B with gray/white of different lightness; the intensities of the background image B and the white area A are weighted by the factor w [0..100] in a way that the background images fades out towards white with increasing w: result := (w*A+(100-w)*B)/100
HSI Fusion	The image fusion is performed by combining the intensity information of the background image B and the hue and saturation of the image layer L. A weighting factor w of zero results in a combined image which receives the entire intensity information from the background photo. Please note that HSI fusion is not transparent to lower layers (i.e. the top layer using HSI fusion controls the colors of the fused image).
Brovey	The Brovey algorithm performs a color-normalized sharpening. The weighting factor controls how much of the HSI information is injected into the high resolution background image.