Creating and Editing a Composite Image

You can create a composite (layered) image in AugerMap by combining any number of colored images over a base, grey-scale image (normally an SED or ABS image). This gives you the ability to compare elemental intensities, map intensities to features, etc.

Each composite you create is a new, independent image. One of the advantages to this is that, once you create the composite, you are free to do what you want with the original images. For example, if you wanted to reduce the size of a file before e-mailing it, you could create a composite, then delete all the other images in the file. The disadvantage is that if you update one of the underlying images (for example, by re-acquiring an SED), you must manually update the composite.

There are two ways to create a composite image: using the mouse and drag-drop, or using the composite dialog. In either case, you must already have at least two image acquisitions, and all but one of them should have colors assigned.

To Create a Composite Image Using Drag+Drop

First, use the Project Window to open a view of the image you want to use for the base (grey-scale) layer of the composite. Next, open a view of the first image you want to layer on top of the base (if you have not done so already, assign a color or colors to this image), and arrange both windows so you can see each of them. Then, “drag” (by clicking the left mouse button and holding it down) the colored image over the base image and “drop” it (by letting go of the button). A new window will open – this window will be your view of the composite. You can add new layers by dragging them on top of this window or by using the composite dialog

To Create a Composite Image Using the Composite Dialog Box

From the Image menu, select the New Composite command. In the Composite Image Dialog, select an image for your base (grey-scale) image from the list of Acquired Images, then click the Add button. Next, select a color image, and click Add. This is your first layer. You may continue to add layers in this fashion. The rest of the dialog functions are described below

Deleting a Composite Image

You delete a composite image the same way you delete any other map component. From the Project Window, select the image, the click Delete from the Edit menu, or hit the Delete key.

Editing a Composite Image

You may edit a composite image at any time after creating it by selecting the image and clicking Edit Composite from the Image menu. This will bring up the Edit Composite Image Dialog. The dialog controls are described below

Comment

Type a comment here – this will be displayed in various locations, including the Project Window. It is optional.

Acquired Images List

This is the list of available images for creating your composite images.

Add

Clicking this button will add the selected image to the list of composite layers. The order you add images in matters – it determines the layering of the images. Normally, you will select a grey-scale image first, then various color images.

Composite Layers List

This is the list of composite layers – images that have already been added to the composite.

Remove

Click this button to remove the selected image from the list of composite layers.

Update

Click this button to update the selected image in the list of composite layers. This will replace the current layer with an updated version of the same image. For example, if you already have a layer for a C1 image, but you have since changed the C1 image (i.e. by changing a color, inverting, etc.), clicking this button will replace the original C1 image layer with the new C1 image layer. In effect, it saves you the trouble of having to remove a region then add it again, if that region’s image characteristics have been changed.

Transparent

Change the transparency of the layers. By default, all layers are opaque – the colors of the layers appear over the base grey-scale image without any of that image showing through. By clicking transparent, the grey-scale base image will be combined with the colored layers, i.e. it will “show through” or be transparent. This option applies to all layers, not just the one selected.

Some Tips on Compositing

Probably the most useful application of composites is layering elemental images on top of an SED or ABS (SEM video) image.

To prepare the SEM image, you may want to enhance the contrast using the Processing command. Next, there are image enhancements available to help in creating a good base image. Sharpening and degraining the image are most helpful. Also, you may choose to use edge-enhancement filters to create topo-map affect, thereby only allowing the edges to show through.

If you use a base SEM image with edge detection, it can be helpful to overlay elements the transparency turned off. Done properly, the result can be an image that shows the gradient of each element’s data against the backdrop of a “wire-frame” SEM image.

If you don’t use edge detection one the base SEM image, leaving the elemental layers transparent will result in the SED showing through. With transparency on, the image your see will detail more the position of each element, without much regard to the amount. This can be most useful when comparing the position of many elements, without regard to their overall concentration.