Geoscience Reference
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ponds to the 5 cm interval equivalent to the sqrt((y(2,1)-y(1,1))^2+(x(2,1)
-x(1,1))^2) pixels gathered using ginput .
ix = 5 * size(I,2) / sqrt((y(2,1)-y(1,1))^2+(x(2,1)-x(1,1))^2);
iy = 5 * size(I,1) / sqrt((y(2,1)-y(1,1))^2+(x(2,1)-x(1,1))^2);
We can now display the image using the new coordinate system where ix and
iy are the width and height of the image, respectively (in centimeters).
imshow(I,'XData',[0 ix],'YData',[0 iy]), axis on
xlabel('Centimeters'), ylabel('Centimeters')
We now digitize the color-intensity transect from the top of the image to
bottom. h e function improfile determines the RGB pixel values C along line
segments dei ned by the coordinates [CX,CY] .
[CX,CY,C] = improfile;
h e scaled image and the polygon are displayed in the same i gure window.
h e three color-intensity curves are plotted in a separate window.
imshow(I,'XData',[0 ix],'YData',[0 iy]), hold on
plot(CX,CY), hold off
figure
plot(CY,C(:,1),'r',CY,C(:,2),'g',CY,C(:,3),'b')
xlabel('Centimeters'), ylabel('Intensity')
h e image and the color-intensity proi les are on a centimeter scale. To detect
the interannual precipitation variability, as recorded in the color intensity of
the sediments, we need to convert the length scale to a time scale. We use the
22 white diatomite layers as time markers to dei ne individual years in the
sedimentary history. We again use ginput to mark the diatomite layers from
top to bottom along the color-intensity transect and store the coordinates of
the laminae in the new variable laminae .
imshow(I,'XData',[0 ix],'YData',[0 iy]), hold on
plot(CX,CY), hold off
laminae = ginput;
To inspect the quality of the age model we plot the image, together with the
polygon and the marked diatomite layers.
imshow(I,'XData',[0 ix],'YData',[0 iy])
hold on
plot(CX,CY)
plot(laminae(:,1),laminae(:,2),'ro')
xlabel('Centimeters'), ylabel('Centimeters')
hold off
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