From 3fb349ff6597aece970179274c87a14ca1150123 Mon Sep 17 00:00:00 2001
From: Jim Martens <github@2martens.de>
Date: Fri, 9 Dec 2016 13:37:13 +0100
Subject: [PATCH] =?UTF-8?q?[BV]=20Mitschrift=20von=208.=20=C3=9Cbung=20ers?=
 =?UTF-8?q?tellt?=
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Signed-off-by: Jim Martens <github@2martens.de>
---
 bv/uebung8_presence.m | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 bv/uebung8_presence.m

diff --git a/bv/uebung8_presence.m b/bv/uebung8_presence.m
new file mode 100644
index 0000000..1b1201e
--- /dev/null
+++ b/bv/uebung8_presence.m
@@ -0,0 +1,42 @@
+cameraman = imread('cameraman.tif');
+cam_fft = fft2(cameraman);
+%figure, imshow(log(abs(fftshift(cam_fft))), []);
+
+[m, n] = size(cameraman);
+mask = zeros(m, n);
+rm = round(m/2) + 1;
+rn = round(n/2) + 1;
+maskSize = 25;
+mask(rm - maskSize : rm + maskSize, rn - maskSize : rn + maskSize) = 1;
+mask = logical(mask);
+figure (1), imshow(mask);
+
+lowPass = fftshift(cam_fft) .* mask;
+figure (2), imshow(log(abs(lowPass)), []);
+maskHigh = ~mask;
+highPass = fftshift(cam_fft) .* maskHigh;
+figure (3), imshow(log(abs(highPass)), []);
+
+new = ifft2(fftshift(lowPass));
+new_high = ifft2(fftshift(highPass));
+figure (4), imshow(new, []);
+figure (5), imshow(new_high, []);
+new2 = new + new_high;
+figure (6), imshow(new2, []);
+
+%
+circuit = imread('circuit.tif');
+v_filter = [-1;1];
+h_filter = [-1 1];
+circuit_v = imfilter(circuit, v_filter);
+circuit_h = imfilter(circuit, h_filter);
+figure (7), imshow(circuit);
+figure (8), imshow(circuit_v, []);
+figure (9), imshow(circuit_h, []);
+
+%
+coins = imread('coins.png');
+filter = [0 1 0;1 -4 1; 0 1 0];
+coins_filtered = imfilter(coins, filter);
+figure (10), imshow(coins);
+figure (11), imshow(coins_filtered);