ETM+ Cloud Removal
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Now working with open water, harbors, and reef areas is equally as difficult because of the subtle variations and hues in the water. Again you need to very aware of these subtle shifts in brightness, intensity, depth, color, hue, and even water or underwater patterns in the reef or harbor.
Begin with sourcing from the small areas that have no clouds or shadows. Again holding down the "Alt" key while pressing the left mouse button over one specific area, then releasing the "Alt" key and moving your mouse to the adjacent cloud for airbrushing over it.
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Now you may have bigger areas of open water to work with, but you still need to be aware that these areas of open water still have a slight and very subtle difference in hue. You will need to continue to source your data near the clouds that you are airbrushing away.
Make sure your strokes go in a uniform direction so any patterns that you do leave behind in the hue of color variation can appear to be underwater reef patterns that are natural to the subsurface texture of the water.
Also make sure that you press and hold down the "Alt" key to change your source reference location often, this will improve on the believability of your final product, and result in better hidden brush strokes.
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Remember to keep your brush strokes uniform in direction. The open water makes it slightly easier because the cloud and the cloud shadow often line up in a single direction. Try to keep these strokes in a believable reef direction. Here it happens that my strokes and the reef direction are in the same line. You may have to be more creative in different circumstances.
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Now again you can see in the image below, that it is even possible to remove clouds from the reefs and open ocean areas as well. Even with the subtle changes in color and hue across this ocean area.
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When you are totally done with removing all the clouds and cloud shadows from the tile.
Navigate the menu control "File->Save As...".
You may need to save several times before you are finally done with all the cloud removal, because some tiles have a lot of really messy clouds, or lots of very tinny clouds. This cloud removal process can become VERY tedious. You may need to save your work and return to it at a later time, when you may have more time to devote to it.
Navigate to a location on your hard drive where you can save the file. Recall that it is best if you make an entire folder for the region you are working on. Type in the appropriate "Path###Row###" designation. You can see that I have added the "-Location" as an additional designator for where the image is.
Make sure the output is set to ".bmp".
Click the "Save" button to save the final cloudless image.
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When the "BMP Options" popup window is displayed, check to make sure the "File Format" is "Windows", the "Depth" is "24 bit".
Click the "OK" button to output the image to the file.
The final cloudless image should look exactly, or very nearly exactly like the image linked below.
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