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# Spatial Resolution / Image Composing

[Laboratory]

Spatial resolution is related to the resolving power to distinguish image details. As image processing is a multidisciplinary field, there are many ways to specify spatial resolution, each one is application oriented.

In remote sensing, it is common to specify the spatial resolution as the size each pixel represents in the real world by the terms ground resolution element and ground resolution distance. As an example the LANDSAT has resolution ranging from 30 m to 120 m. In this case as smaller the resolutin distance, the better one can resolve image spatial contents.

In medical imaging, the resolution is also used as in remote sensing, but using milimeters as their standard unit. Typical CT (Computer Tomography) Scanners have pixel size of 1 mm.

In document industry, the resolution is used as number of pixels per world dimension. As an example desktop scanners has resolution of 600 dpi (dots per inch).

What it important is to understand the concept behind the spatial resolution term, no matter which are you are in.

Shown below are two images of the moon sampled at two different resolutions. In order to observe resolution effects, a small image of a ruler is superimposed on both moon images. The ruler measures the number of pixels within an image.

a)20 km/pixel; b)10 km/pixel
a) | b)

There are approximately 27 pixels across the diameter of the lunar crater shown on the first image, and approximately 55 pixels across the crater shown on the second image on the right. The image at the right has higher resolution. This implies that it is possible to measure its features more accurately. Assume the crater has a diameter of 550 km, then the resolution of the image on the left is 20 km/pixel while the image on the right has a resolution of 10 km/pixel.

- Lab: Spatial Resolution / Image Composing
- Other Examples