Using the Thumbnail viewer

You can use the Thumbnail viewer in either of two modes:

Grayscale
RGB

In Grayscale mode, you can click an image in the tiled-image array. You can then click View to display the image in grayscale and at full-size in the Focus window.

In RGB mode, you can click up to three images in the array. Notice that the thumbnails are outlined in red, green, or blue respectively according to the order in which you select them. That is, the first image you click is red, the second is green, and the third is blue. You can select the channel you want based on the order in which you click. Each time you click an image, it cycles through red, green, and blue. You can then click View to display the image in composite RGB at full-size in the Focus window.

Constraining the viewer
You can constrain the contents of the Thumbnail viewer to an area of interest (AOI), such as a specific feature. To do so, in the view pane of the Focus window, zoom to the AOI, and then, in the Thumbnail viewer, click Reload. The thumbnails are recreated by using the extents visible in the Focus view pane.

Refreshing the viewer
When you make changes in the Thumbnail viewer, such as to the channel numbers, click Reload to update the display. For example, you can enter specific channels in the Display ranges box, and then click Reload to have only thumbnails of those channels appear in the Thumbnail viewer.

To specify the bands that you want to view
1. In the Display ranges box, specify the bands that you want to view.
  You can either enter the channel number or the wavelength. To enter wavelength, the metadata must contain band centers. By default, all channels are displayed.
2. Based on the display range you specified, do one of the following:
  - If the range is channel numbers, make sure Channel is selected.
  - If the range is wavelengths stored in the metadata segment of the file, click Wavelength.
To use the minimum and maximum values in the image to apply a histogram to the thumbnail
- Select the Intensity Normalization check box.
With a clear check box, the histogram includes the entire range of values from all the channels.
To view the image as a grayscale layer
1. Make sure Grayscale is selected.
2. On the toolbar, click Select Channel, and then in the view pane, click the thumbnail you want to view.
  The channel number of the thumbnail you select is displayed in the box beside Grayscale.
To view the image as RGB
1. Make sure RGB is selected.
2. On the toolbar, click Select Channel, and then in the view pane, click the thumbnails that you want to use for the red, green, and blue channels.
  The thumbnails are highlighted in the colors of the corresponding channels and the channel numbers are displayed in the boxes beside Red, Green, and Blue, repsectively.
To view the thumbnail or thumbnails in the Focus window
- Click View.
A map and area are added to the Maps tab. With Grayscale selected, the grayscale image is displayed full-size in the Focus window. With RGB selected, a full-size, composite RGB image is displayed.
To update the display in the Thumbnail viewer
- Click Reload.
That is, if you made any changes to the settings, such as the channel numbers, the display is reloaded based on the changes you made.

For information about the toolbar buttons, see Thumbnail viewer toolbar.