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Creating a false-color composite image with Geographic Imager for Adobe Photoshop

One of the powerful remote sensing tools available in Adobe Photoshop is to detect the land surface information by creating a false color composite image. Multispectral images contain the reflectance information from the visible and invisible electromagnetic spectrum. Using this information, we can detect many kinds of land surface information. For this example, we will detect the green area using Landsat images imported by Geographic Imager for Adobe Photoshop, which ensures all the georeference information is maintained.

Landsat images consist of several gray scale images, with each image containing one of the bands of the electromagnetic spectrum. For example, in the Geographic Imager tutorial folder, there are a set of Landsat images available. Those gray scale images are from Band 1, 2, 3, 4, 5, 7, and 8.

Landsat Images available in the Geographic Imager tutorial folder

These images need to be combined into one image. The Adobe Photoshop function called “Merge Channels” produces one image by combining mulitple gray scaled images. With this example, those gray scale images from Band 2, 3, and 4 will be merged into one image by assigning a color for each band.

Image analysis trick

1) Open the Landsat image from Band 2, 3, and 4. Note that the Geographic Imager panel shows the information on the coordinate system and image extents.

Georeference information on the Geographic Imager panel

2) Open the Channel panel (Window > Channels). Choose “Merge Channels” from the panel options menu.

Merge Channels

3) In the Merge Channels dialog box, select RGB color as the mode.

Merge Channels - RGB

4) In the Merge RGB Channels dialog box, specify the band for each channel: band 4 for the red channel, band 3 for the green channel, and band 2 for the blue channel.

Specifying the channels for Merge channels

5) As a result, those three images from Band 2, 3, and 4, are assigned to the Blue, Green and Red channels, respectively.

Merge channels result in the Channels panel

6) Now, let’s take a look at the image!

Merge channels result - false color composite image

This combination of false-color makes vegetation appear as red tones. The bright red color indicates the growing vegtation. Water is displayed in a blue color. When the water contains high sediment concentrations, the color will be lighter blue. Urban areas will appear gray to blue-gray in color.

7) All the georeferenced information is inherited by the new image with merged channels from those original images. The georeference information is displayed in the Geographic Imager panel.

The georeference information was maintained from the original georeferenced image.


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