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Doubling Landsat-7 Image Resolution
Use Landsat-7 panchromatic band to double true color resolution.
By Ryan Foss

This tutorial desribes how to get real sattelite imagrey and convert it into usable graphics.

The image to the right illustrate the level of detail achievable. It might not seem much, but you have access to the entire world at this resolution!

image of 2x res


 

1

Pick up with True Color image

With the combined true color bands 1, 2 and 3, we can double the resolution using band 8.

This tutorial expands on the tutorial Getting and Using Satellite Image Data, picking up where it left off. Essentially you should have combined LANDSAT RAW image bands into a true color image. We can use this to represent the color, while using the higher resolution band 8 to represent the intensity. Essentially, band 8 is a higher resolution image representing the intensity of light emitted.

I should warn you that working with these images is intense, requiring lots of resources (memory, hard drive space, processor, etc.). Thus, you may find that you’ll need to be inventive (such as dividing the image into parts) in order to produce results.

 

2

Double Resolution

Double the resolution of your true color image.

Image>Image Size and set the percent to 200. Be sure to constrain proportions.

 

3

LAB Color Mode

Convert to LAB color mode. Image>Mode>LAB color. This converts your RGB (red-green-blue channels) to LAB channels, representing the lightness (L), the green-red channel (A) and blue-yellow (B). Essentially, it combines your color information into the A and B channels, leaving the L channel to define the lightness. Since Band 8 is essentially light intensity, we can replace the L channel with Band 8. Open the band 8 image and select-all (Ctrl-a) and copy (Ctrl-c). Close band 8 and in your LAB image, paste into the L channel.

4

Color Balance

Now you’ll need to do some color adjustment to get good results. It’s up to you if you want to do it in LAB mode or back in RGB mode. But after some fuss, you should be able to get double the resolution than the original true color combination.

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