Geoscience Reference
In-Depth Information
Warning: Image is too big to fit on screen; displaying at 33%
and wait for the next response
Click on lower left and upper right corner, then <return>
h e image window can be scaled according to user preference. Clicking on
the lower let and upper right corners dei nes the dimensions of the image.
h ese changes are registered by pressing
return
. h e routine then references
the image to the coordinate system and waits for the input of the points we
wish to digitize from the image.
Click on data points to digitize, then <return>
We i nish the input by again pressing
return
. h e
xy
coordinates of our
digitized points are now stored in the variable
data
. We can now use these
vector data for other applications.
8.8 Image Enhancement, Correction and Rectii cation
h is section introduces some fundamental tools for image enhancement,
correction and rectii cation. As an example we use an image of varved
sediments deposited around 33 kyrs ago in a landslide-dammed lake in the
Quebrada de Cafayate of Argentina (25°58.900'S 65°45.676'W) (Trauth et al.
1999, 2003). h e diapositive was taken on 1st October 1996 with a i lm-based
single-lens rel ex (SLR) camera. A 30-by-20 cm print was made from the
slide, which has been scanned using a l atbed scanner and saved as a 394 KB
JPEG i le. We use this as an example because it demonstrates some problems
that we can solve with the help of image enhancement (Fig. 8.6). We then use
the image to demonstrate how to measure color-intensity transects for use in
time series analysis (Section 8.9).
We can read and decompress the i le
varves_original.jpg
by typing
clear
I1 = imread('varves_original.jpg');
which yields a 24-bit RGB image array
I1
in the MATLAB workspace. Typing
whos
yields
Name Size Bytes Class Attributes
I1 1096x1674x3 5504112 uint8
