I am using the following lines of code for edge detection using canny edge detector :
I=imread('bradd.tif');
figure,imshow(I);
IDtemp = im2double(I);
[r c]=size(I);
ID(r,c) = 0;
IDx(r,c) = 0;
IDfil(r,c) = 0;
IDxx(r,c) = 0;
IDy(r,c) = 0;
IDyy(r,c) = 0;
mod(r,c) = 0;
for i= 1 : r+4
for j = 1:c+4
if(i<=2 || j<=2 || i>=r+3 || j>=c+3)
ID(i,j) = 0;
else
ID(i,j) = IDtemp(i-2,j-2);
end;
end
end
%figure,imshow(ID);
filter=[2 4 5 4 2;4 9 12 9 4;5 12 15 12 5;4 9 12 9 4;2 4 5 4 2];
for i=1:5
for j=1:5
filter(i,j)=filter(i,j)/159;
end
end
%figure,imshow(filter);
for v = 3 : r
for u = 3 : c
sum = 0;
for i = -2 : 2
for j = -2 : 2
sum = sum + (ID(u+i, v+j) * filter(i+3, j+3));
end
end
IDx(u,v) = sum;
end
end
%figure,imshow(IDx);
IDxtemp = IDx;
for i= 1 : r+2
for j = 1:c+2
if(i<=1 || j<=1 || i>=r || j>=c)
IDfil(i,j) = 0;
else
IDfil(i,j) = IDxtemp(i-1,j-1);
end;
end
end
%figure,imshow(IDfil);
Mx = [-1 0 1; -2 0 2; -1 0 1]; % Sobel Mask in X-Direction
My = [-1 -2 -1; 0 0 0; 1 2 1]; % Sobel Mask in Y-Direction
for u = 2:r
for v = 2:c
sum1 = 0;
for i=-1:1
for j=-1:1
sum1 = sum1 + IDfil(u + i, v + j)* Mx(i + 2,j + 2);
end
end
IDxx(u,v) = sum1;
end;
end
%figure,imshow(IDxx);
for u = 2:r
for v = 2:c
sum2 = 0;
for i=-1:1
for j=-1:1
sum2 = sum2 + IDfil(u + i, v + j)* My(i + 2,j + 2);
end
end
IDyy(u,v) = sum2;
end
end
%figure,imshow(IDyy);
for u = 1:r
for v = 1:c
mod(u,v) = sqrt(IDxx(u,v)^2 + IDyy(u,v)^2) ;
%mod(u,v) = sqrt(IDxx(u,v)^2 + IDyy(u,v)^2);
end
end
%figure,imshow(mod);
modtemp = mod;
for i= 1 : r+2
for j = 1:c+2
if(i<=1 || j<=1 || i>=r || j>=c)
mod(i,j) = 0;
else
mod(i,j) = modtemp(i-1,j-1);
end;
end
end
%figure,imshow(mod);
theta(u,v) = 0;
supimg(u,v) = 0;
ntheta(u,v) = 0;
for u = 2 : r
for v = 2 : c
theta(u,v) = atand(IDyy(u,v)/IDxx(u,v));
if ((theta(u,v) > 0 ) && (theta(u,v) < 22.5) || (theta(u,v) > 157.5) && (theta(u,v) < -157.5))
ntheta(u,v) = 0;
end
if ((theta(u,v) > 22.5) && (theta(u,v) < 67.5) || (theta(u,v) < -112.5) && (theta(u,v) > -157.5))
ntheta(u,v) = 45;
end
if ((theta(u,v) > 67.5 && theta(u,v) < 112.5) || (theta(u,v) < -67.5 && theta(u,v) > 112.5))
ntheta(u,v) = 90;
end
if ((theta(u,v) > 112.5 && theta(u,v) <= 157.5) || (theta(u,v) < -22.5 && theta(u,v) > -67.5))
ntheta(u,v) = 135;
end
if (ntheta(u,v) == 0)
if (mod(u, v) > mod(u, v-1) && mod(u, v) > mod(u, v+1))
supimg(u,v) = mod(u,v);
else supimg(u,v) = 0;
end
end
if (ntheta(u,v) == 45)
if (mod(u, v) > mod(u+1, v-1) && mod(u, v) > mod(u-1, v+1))
supimg(u,v) = mod(u,v);
else supimg(u,v) = 0;
end
end
if (ntheta(u,v) == 90)
if (mod(u, v) > mod(u-1, v) && mod(u, v) > mod(u+1, v))
supimg(u,v) = mod(u,v);
else supimg(u,v) = 0;
end
end
if (ntheta(u,v) == 135)
if (mod(u, v) > mod(u-1, v-1) && mod(u, v) > mod(u+1, v+1))
supimg(u,v) = mod(u,v);
else supimg(u,v) = 0;
end
end
end
end
%figure,imshow(ntheta);
th = 0.2;
tl = 0.1;
resimg(u,v)= 0;
for u = 2 : r-1
for v = 2 : c-1
if(supimg(u,v) > th)
resimg(u,v) = 1;
else
if(supimg(u,v) >= tl && supimg(u,v) <= th )
resimg(u,v) = 1;
else
if (supimg(u,v) < tl)
resimg(u,v) = 0;
end
end
end
if (supimg(u-1,v-1) > th || supimg(u,v-1) > th || supimg(u+1,v-1) > th || supimg(u+1,v) > th || supimg(u+1,v+1) > th || supimg(u,v+1) > th || supimg(u-1,v+1) > th || supimg(u-1,v) > th)
resimg(u,v) = 1;
else
resimg(u,v) = 0;
end
end
end
figure,imshow(supimg);
figure,imshow(resimg);
However, for some of the images it is working fine, while for others it is showing the following error :
Index exceeds matrix dimensions.
Error in canny_edge (line 45)
sum = sum + (ID(u+i, v+j) * filter(i+3, j+3));
Can someone help me sort out this problem ??
Thanks and Regards.
Your loop ranges are in the wrong order leading to the error. If you modify your loop ranges to this
for u = 3 : r
for v = 3 : c
sum = 0;
for i = -2 : 2
for j = -2 : 2
sum = sum + (ID(u+i, v+j) * filter(i+3, j+3));
end
end
IDx(u,v) = sum;
end
end
the problem is solved.
My guess is that the code worked only for square images with c==r.
Note you are not making use of Matlab's vectorization capability, which allows you to shorten the first steps to:
ID = [zeros(2,c+4) ; [zeros(r,2) IDtemp zeros(r,2)]; zeros(2,c+4)];
filter=[2 4 5 4 2;4 9 12 9 4;5 12 15 12 5;4 9 12 9 4;2 4 5 4 2];
filter=filter/159;
for u = 1 : r
for v = 1 : c
IDx(u,v) = sum(reshape(ID(u+[0:4], v+[0:4]).* filter,25,1));
end
end
and this last loop can also be collapsed further but that might make readability an issue.
(edit) The loop can (for instance) be replaced with
IDx = conv2(ID, filter,'same');
Related
I am getting an error when I run this code for disc waves. The code is attached.
The Error is in line 137 and 292. Please help in resolving issue.
function waves
% WAVES Wave equation in one and two space dimensions.
% The two-dimensional domains include a pi-by-pi square, a unit disc,
% a three-quarter circular sector and the L-shaped union of three squares.
% The eigenfunctions of the square are sin(m*x)*sin(n*y). With polar
% coordinates, the eigenfunctions of the disc and the sector involve Bessel
% functions. The eigenfunctions of the L-shaped domain also involve
% Bessel functions and are computed by the MATLAB function membranetx.m.
% 2-D eigenvalues and eigenfunctions
m = 11; % Determines number of grid points
speed = 1;
bvals = [1; 0; 0; 0; 0];
t = 0;
while bvals(5) == 0
% Initialize figure
shg
clf reset
set(gcf,'doublebuffer','on','menubar','none','tag','', ...
'numbertitle','off','name','Waves','colormap',hot(64));
for k= 1:5
b(k) = uicontrol('style','toggle','value',bvals(k), ...
'units','normal','position',[.15*k .01 .14 .05]);
end
set(b(1),'style','pop','string', ...
{'1-d','square','disc','sector'})
set(b(2),'string','modes/wave')
set(b(3),'string','slower')
set(b(4),'string','faster')
set(b(5),'string','close')
if bvals(3)==1
speed = speed/sqrt(2);
set(b(3),'value',0);
end
if bvals(4)==1
speed = speed*sqrt(2);
set(b(4),'value',0);
end
bvals = cell2mat(get(b,'value'));
region = bvals(1);
modes = bvals(2)==0;
if region == 1
% 1-D
x = (0:4*m)/(4*m)*pi;
orange = [1 1/3 0];
gray = get(gcf,'color');
if modes
% 1-D modes
for k = 1:4
subplot(2,2,k)
h(k) = plot(x,zeros(size(x)));
axis([0 pi -3/2 3/2])
set(h(k),'color',orange,'linewidth',3)
set(gca,'color',gray','xtick',[],'ytick',[])
end
delta = 0.005*speed;
bvs = bvals;
while all(bvs == bvals)
t = t + delta;
for k = 1:4
u = sin(k*t)*sin(k*x);
set(h(k),'ydata',u)
end
drawnow
bvs = cell2mat(get(b,'value'));
end
else
% 1-D wave
h = plot(x,zeros(size(x)));
axis([0 pi -9/4 9/4])
set(h,'color',orange,'linewidth',3)
set(gca,'color',gray','xtick',[],'ytick',[])
delta = 0.005*speed;
a = 1./(1:4);
bvs = bvals;
while all(bvs == bvals)
t = t + delta;
u = zeros(size(x));
for k = 1:4
u = u + a(k)*sin(k*t)*sin(k*x);
end
set(h,'ydata',u)
drawnow
bvs = cell2mat(get(b,'value'));
end
end
elseif region <= 5
switch region
case 2
% Square
x = (0:2*m)/(2*m)*pi;
y = x';
lambda = zeros(4,1);
V = cell(4,1);
k = 0;
for i = 1:2
for j = 1:2
k = k+1;
lambda(k) = i^2 + j^2;
V{k} = sin(i*y)*sin(j*x);
end
end
ax = [0 pi 0 pi -1.75 1.75];
case 3
% Disc, mu = zeros of J_0(r) and J_1(r)
mu = [bjzeros(0,2) bjzeros(1,2)];
[r,theta] = meshgrid((0:m)/m,(-m:m)/m*pi);
x = r.*cos(theta);
y = r.*sin(theta);
V = cell(4,1);
k = 0;
for j = 0:1
for i = 1:2
k = k+1;
if j == 0
V{k} = besselj(0,mu(k)*r);
else
V{k} = besselj(j,mu(k)*r).*sin(j*theta);
end
V{k} = V{k}/max(max(abs(V{k})));
end
end
lambda = mu.^2;
ax = [-1 1 -1 1 -1.75 1.75];
case 4
% Circular sector , mu = zeros of J_(2/3)(r) and J_(4/3)(r)
mu = [bjzeros(2/3,2) bjzeros(4/3,2)];
[r,theta] = meshgrid((0:m)/m,(3/4)*(0:2*m)/m*pi);
x = r.*cos(theta+pi);
y = r.*sin(theta+pi);
V = cell(4,1);
k = 0;
for j = 1:2
for i = 1:2
k = k+1;
alpha = 2*j/3;
V{k} = besselj(alpha,mu(k)*r).*sin(alpha*theta);
V{k} = V{k}/max(max(abs(V{k})));
end
end
lambda = mu.^2;
ax = [-1 1 -1 1 -1.75 1.75];
case 5\
% L-membrane
x = (-m:m)/m;
y = x';
lambda = zeros(4,1);
V = cell(4,1);
for k = 1:4
[L lambda(k)] = membranetx(k,m,9,9);
L(m+2:2*m+1,m+2:2*m+1) = NaN;
V{k} = rot90(L,-1);
end
ax = [-1 1 -1 1 -1.75 1.75];
end
if modes
% 2-D modes
p = [.02 .52 .02 .52];
q = [.52 .52 .02 .02];
for k = 1:4
axes('position',[p(k) q(k) .46 .46]);
h(k) = surf(x,y,zeros(size(V{k})));
axis(ax)
axis off
view(225,30);
caxis([-1.5 1]);
end
delta = .08*speed;
mu = sqrt(lambda(:));
bvs = bvals;
while all(bvs == bvals)
t = t + delta;
for k = 1:4
U = 1.5*sin(mu(k)*t)*V{k};
set(h(k),'zdata',U)
set(h(k),'cdata',U)
end
drawnow
bvs = cell2mat(get(b,'value'));
end
else
% 2-D wave
h = surf(x,y,zeros(size(V{1})));
axis(ax);
axis off
view(225,30);
caxis([-1.5 1]);
delta = .02*speed;
mu = sqrt(lambda(:));
a = 1.25./(1:4);
bvs = bvals;
while all(bvs == bvals)
t = t + delta;
U = zeros(size(V{1}));
for k = 1:4
U = U + a(k)*sin(mu(k)*t)*V{k};
end
set(h,'zdata',U)
set(h,'cdata',U)
drawnow
bvs = cell2mat(get(b,'value'));
end
end
elseif region == 6
figure
bizcard
set(b(1),'value',1)
end
% Retain uicontrol values
bvals = cell2mat(get(b,'value'));
end
close
% -------------------------------
function z = bjzeros(n,k)
% BJZEROS Zeros of the Bessel function.
% z = bjzeros(n,k) is the first k zeros of besselj(n,x)
% delta must be chosen so that the linear search can take
% steps as large as possible without skipping any zeros.
% delta is approx bjzero(0,2)-bjzero(0,1)
delta = .99*pi;
Jsubn = inline('besselj(n,x)''x','n');
a = n+1;
fa = besselj(n,a);
z = zeros(1,k);
j = 0;
while j < k
b = a + delta;
fb = besselj(n,b);
if sign(fb) ~= sign(fa)
j = j+1;
z(j) = fzerotx(Jsubn,[a b],n);
end
a = b;
fa = fb;
end
Problem (THE QUESTION)
Strokes to paint
Alex wants to paint a picture. In one stroke, Alex can only paint the same colored cells which are joined via some edge.
Given the painting as a 2-dimensional array of letters indicating colors, determine the minimum number of strokes to completely paint the picture.
Example: The canvas height, h = 3 and width, w = 5 is to be painted with picture=["aabba", "aabba", "aaacb"]. The diagram below shows the 5 strokes needed to paint the canvas. It takes two strokes each for colors a and b, and one for c
a a b b a
a a b b a
a a a c b
Function Description Complete the function strokesRequired in the editor below. The function must return an integer, the minimum number of strokes required to paint the canvas.
strokesRequired has the following parameter(s): picture[picture[0],...picture[h-1]] an array of strings where each string represents one row of the picture to be painted
Constraints
1 <= h <= 10^5
1<= w <= 10^5
1 <= h*w <= 10^5
len(pictureffl) = w (where 0 <= i < h)
picture[i][j] <- (a, b, c) (where 0 <= i < h and 0 <= j < w)
Hello.. so i attended one company interview and they asked me this problem and iam not getting any ideas please help
class Paint:
def __init__(self, row, col, arr):
self.ROW = row
self.COL = col
self.arr = arr
def visit(self, i, j, visited):
ele = self.arr[i][j]
for k in range(i,self.ROW):
for l in range(j, self.COL):
if self.arr[k][l]==ele:
visited[k][l]=True
v=l
if l>0 and self.arr[k][l-1]==ele and not visited[k][l-1]:
self.visit(k, l-1, visited)
if k>0 and self.arr[k-1][l]==ele and not visited[k-1][l]:
self.visit(k-1, l, visited)
elif l>=v:
break
# 2D matrix
def count_cells(self):
# Make an array to mark visited cells.
# Initially all cells are unvisited
visited = [[False for j in range(self.COL)]for i in range(self.ROW)]
# Initialize count as 0 and travese
count = 0
for i in range(self.ROW):
for j in range(self.COL):
# If a cell value false then not visited yet
# then visit
if visited[i][j] == False:
# Visit all cells in the array
self.visit(i, j, visited)
print(visited)
count += 1
return count
arr = ["aabba", "aabba", "aaacb"]
row = len(arr)
col = len(arr[0])
p = Paint(row, col, arr)
print (p.count_cells())
function visit(picture, i, j, visitedBoxes) {
const currentElem = picture[i][j];
if (picture[i][j] === currentElem) {
visitedBoxes[i][j] = true;
// go in four directions
// south
if (i + 1 < picture.length && picture[i+1][j] === currentElem && visitedBoxes[i+1][j] === false) {
visit(picture, i+1, j, visitedBoxes);
}
// west
if (j+ 1 < picture[i].length && picture[i][j+1] === currentElem && visitedBoxes[i][j+1] === false) {
visit(picture, i, j+1, visitedBoxes);
}
// north
if (i > 0 && picture[i-1][j] === currentElem && visitedBoxes[i-1][j] === false) {
visit(picture, i-1, j, visitedBoxes);
}
// west
if (j > 0 && picture[i, j-1] === currentElem && visitedBoxes[i, j-1] === false) {
visit(picture, i, j-1, visitedBoxes);
}
}
}
function countStrokes(picture) {
const visitedBoxes = [];
for (let i = 0; i < picture.length; i++) {
visitedBoxes[i] = [];
for(let j = 0; j < picture[i].length; j++) {
visitedBoxes[i][j] = false;
}
}
let srokesCount = 0;
for (let i = 0; i < picture.length; i++) {
for (let j = 0; j < picture[i].length; j++) {
if (!visitedBoxes[i][j]) {
visit(picture, i, j, visitedBoxes);
srokesCount++;
}
}
}
console.log('Strokes Count', srokesCount);
}
countStrokes(['aaaba', 'ababa', 'aacba']);
This will output 5.
Also you can use
function printVisited(visitedBoxes) {
for (let i = 0; i < visitedBoxes.length; i++) {
let str = ''
for(let j = 0; j < visitedBoxes[i].length; j++) {
str += visitedBoxes[i][j] ? '1 ': '0 ';
}
console.log(str);
}
console.log('-------------');
}
to print after each loop.
Output
1 1 1 0 0
1 0 1 0 0
1 1 0 0 0
-------------
1 1 1 1 0
1 0 1 1 0
1 1 0 1 0
-------------
1 1 1 1 1
1 0 1 1 1
1 1 0 1 1
-------------
1 1 1 1 1
1 1 1 1 1
1 1 0 1 1
-------------
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
-------------
Strokes Count 5
I have written a code that reads an image and does scaling of 2 units in x-axis direction. Scaling matrix is filled by values that are read from a text file.
Scaling Matrix looks like
2 0 0
0 1 0
0 0 1
Original Image
Transformed Image (Scaling of 2 units in X-direction)
Code
file = importdata('transform_c.txt');
fileData = file.data;
image = imread('mecca06.pgm');
[row, col] = size(image);
scalingMatrix = zeros(3,3);
scalingMatrix(1,1) = fileData(2);
scalingMatrix(1,2) = fileData(3);
scalingMatrix(1,3) = fileData(4);
scalingMatrix(2,1) = fileData(5);
scalingMatrix(2,2) = fileData(6);
scalingMatrix(2,3) = fileData(7);
scalingMatrix(3,1) = fileData(8);
scalingMatrix(3,2) = fileData(9);
scalingMatrix(3,3) = fileData(10);
m1Inverse = inv(scalingMatrix);
outputImage = applyTransformation(image, row, col, m1Inverse);
figure
imshow(outputImage);
function outImage = applyTransformation(image, row, col, m1Inverse)
points = zeros(3,1);
for i=1:row
for j=1:col
points(1,1) = i;
points(2,1) = j;
points(3,1) = 1;
m2 = m1Inverse * points;
x = m2(1,1);
y = m2(2,1);
xlb = floor(x);
ylb = floor(y);
if(xlb <= 0)
xlb = 1;
end
if(xlb > row)
xlb = row;
end
if(ylb <= 0)
ylb = 1;
end
if(ylb > col)
ylb = col;
end
xub = xlb+1;
yub = ylb+1;
if(xub <= 0)
xub = 1;
end
if(xub > row)
xub = row;
end
if(yub <= 0)
yub = 1;
end
if(yub > col)
yub = col;
end
exub = xub-x;
eyub = yub-y;
exlb = x-xlb;
eylb = y-ylb;
outImage(i,j) = (exub*eyub*image(xlb,ylb))+(exlb*eyub*image(xub,ylb))+(exub*eylb*image(xlb,yub))+(exlb*eylb*image(xub,yub));
end
end
end
My question is how can i modify the above code to get uncropped image ?
I want to get following image
Try to see if this code produces the result you need:
img = imread('aSxLS.png');
scale = [
2 0 0
0 1 0
0 0 1
];
tform = maketform('affine',inv(scale));
img_tform = imtransform(img,tform,'bilinear');
figure();
imshow(img);
figure();
imshow(img_tform);
I have this program that finds the vanishing point for a given set of images. Is there a way to find the distance from the camera and the vanishing point?
Also once the vanishing point is found out, I manually need to find the X and Y coordinates using the tool provided in matlab. How can i code a snippet that writes all the X and Y coordinates into a text or excel file?
Also is there a better and simpler way to find the vanishing point in matlab?
Matlab Calling Function to find Vanishing Point:
clear all; close all;
dname = 'Height';
files = dir(dname);
files(1) = [];
files(1) = [];
for i=1:size(files, 1)
original = imread(fullfile(dname, files(i).name));
original = imresize(original,0.35);
im = im2double(rgb2gray(original));
[row, col] = findVanishingPoint(im);
imshow(original);hold;plot(col,row,'rx');
saveas(gcf,strcat('Height_Result',num2str(i)),'jpg');
close
end
The findVanishingPoint function:
function [row, col] = findVanishingPoint(im)
DEBUG = 0;
IM = fft2(im);
ROWS = size(IM,1); COLS = size(IM,2);
PERIOD = 2^floor(log2(COLS)-5)+2;
SIZE = floor(10*PERIOD/pi);
SIGMA = SIZE/9;
NORIENT = 72;
E = 8;
[C, S] = createGaborBank(SIZE, PERIOD, SIGMA, NORIENT, ROWS, COLS, E);
D = ones(ROWS, COLS);
AMAX = ifftshift(real(ifft2(C{1}.*IM)).^2+real(ifft2(S{1}.*IM))).^2;
for n=2:NORIENT
A = ifftshift(real(ifft2(C{n}.*IM)).^2+real(ifft2(S{n}.*IM))).^2;
D(find(A > AMAX)) = n;
AMAX = max(A, AMAX);
if (DEBUG==1)
colormap('hot');subplot(131);imagesc(real(A));subplot(132);imagesc(real(AMAX));colorbar;
subplot(133);imagesc(D);
pause
end
end
if (DEBUG==2)
figure('DoubleBuffer','on');
end
T = mean(AMAX(:))-3*std(AMAX(:));
VOTE = zeros(ROWS, COLS);
for row=round(1+SIZE/2):round(ROWS-SIZE/2)
for col=round(1+SIZE/2):round(COLS-SIZE/2)
if (AMAX(row,col) > T)
indices = lineBresenham(ROWS, COLS, col, row, D(row, col)*pi/NORIENT-pi/2);
VOTE(indices) = VOTE(indices)+AMAX(row,col);
end
end
if (DEBUG==2)
colormap('hot');imagesc(VOTE);pause;
end
end
if (DEBUG==2)
close
end
M=1;
[b index] = sort(-VOTE(:));
col = floor((index(1:M)-1) / ROWS)+1;
row = mod(index(1:M)-1, ROWS)+1;
col = round(mean(col));
row = round(mean(row));
The creatGaborBank function:
function [C, S] = createGaborBank(SIZE, PERIOD, SIGMA, NORIENT, ROWS, COLS, E)
if (length(NORIENT)==1)
orientations=[1:NORIENT];
else
orientations = NORIENT;
NORIENT = max(orientations);
end
for n=orientations
[C{n}, S{n}] = gabormask(SIZE, SIGMA, PERIOD, n*pi/NORIENT);
C{n} = fft2(padWithZeros(C{n}, ROWS, COLS));
S{n} = fft2(padWithZeros(S{n}, ROWS, COLS));
end
The gabormask function:
function [cmask, smask] = gabormask(Size, sigma, period, orient, E)
if nargin < 5; E = 8; end;
if nargin < 4; orient = 0; end;
if nargin < 3; period = []; end;
if nargin < 2; sigma = []; end;
if nargin < 1; Size = []; end;
if isempty(period) & isempty(sigma); sigma = 5; end;
if isempty(period); period = sigma*2*sqrt(2); end;
if isempty(sigma); sigma = period/(2*sqrt(2)); end;
if isempty(Size); Size = 2*round(2.575*sigma) + 1; end;
if length(Size) == 1
sx = Size-1; sy = sx;
elseif all(size(Size) == [1 2])
sy = Size(1)-1; sx = Size(2)-1;
else
error('Size must be scalar or 1-by-2 vector');
end;
hy = sy/2; hx = sx/2;
[x, y] = meshgrid(-hx:sx-hx, -hy:sy-hy);
omega = 2*pi/period;
cs = omega * cos(orient);
sn = omega * sin(orient);
k = -1/(E*sigma*sigma);
g = exp(k * (E*x.*x + y.*y));
xp = x * cs + y * sn;
cx = cos(xp);
cmask = g .* cx;
sx = sin(xp);
smask = g .* sx;
cmask = cmask - mean(cmask(:));
cmask = cmask/sum(abs(cmask(:)));
smask = smask - mean(smask(:));
smask = smask/sum(abs(smask(:)));
The padWithZeros function:
function out = padWithZeros(in, ROWS, COLS)
out = padarray(in,[floor((ROWS-size(in,1))/2) floor((COLS-size(in,2))/2)],0,'both');
if size(out,1) == ROWS-1
out = padarray(out,[1 0],0,'pre');
end
if size(out,2) == COLS-1
out = padarray(out,[0 1],0,'pre');
end
The findHorizonEdge function:
function row = findHorizon(im)
DEBUG = 2;
ROWS = size(im,1); COLS = size(im,2);
e = edge(im,'sobel', [], 'horizontal');
dd = sum(e, 2);
N=3;
row = 1;
M = 0;
for i=1+N:length(dd)-N
m = sum(dd(i-N:i+N));
if (m > M)
M = m;
row = i;
end
end
imshow(e);pause
The findHorizon function:
function row = findHorizon(im)
DEBUG = 2;
IM = fft2(im);
ROWS = size(IM,1); COLS = size(IM,2);
PERIOD = 2^floor(log2(COLS)-5)+2;
SIZE = floor(10*PERIOD/pi);
SIGMA = SIZE/9;
NORIENT = 72;
E = 16;
orientations = [NORIENT/2-10:NORIENT/2+10];
[C, S] = createGaborBank(SIZE, PERIOD, SIGMA, orientations, ROWS, COLS, E);
ASUM = zeros(ROWS, COLS);
for n=orientations
A = ifftshift(real(ifft2(C{n}.*IM)).^2+real(ifft2(S{n}.*IM))).^2;
ASUM = ASUM + A;
if (DEBUG==1)
colormap('hot');subplot(131);imagesc(real(A));subplot(132);imagesc(real(AMAX));colorbar;
pause
end
end
ASUM(1:round(1+SIZE/2), :)=0; ASUM(end-round(SIZE/2):end, :)=0;
ASUM(:,end-round(SIZE/2):end)=0; ASUM(:, 1:1+round(SIZE/2))=0;
dd = sum(ASUM, 2);
[temp, row] = sort(-dd);
row = round(mean(row(1:10)));
if (DEBUG == 2)
imagesc(ASUM);hold on;line([1:COLS],repmat(row,COLS));
pause
end
The lineImage function:
function v = lineimage(x0, y0, angle, s)
if (abs(tan(angle)) > 1e015)
a(1,:) = repmat(x0,s(1),1)';
a(2,:) = [1:s(1)];
elseif (abs(tan(angle)) < 1e-015)
a(2,:) = repmat(y0,s(2),1)';
a(1,:) = [1:s(2)];
else
k = tan(angle);
hiX = round((1-(s(1)-y0+1)+k*x0)/k);
loX = round((s(1)-(s(1)-y0+1)+k*x0)/k);
temp = max(loX, hiX);
loX = max(min(loX, hiX), 1);
hiX = min(s(2),temp);
a(1,:) = [loX:hiX];
a(2,:) = max(1, floor(s(1)-(k*a(1,:)+(s(1)-y0+1)-k*x0)));
end
v = (a(1,:)-1).*s(1)+a(2,:);
The lineVector function:
function [abscissa, ordinate] = linevector(x0, y0, angle, s)
if (rad2deg(angle) == 90)
abscissa = repmat(x0,s(1),1);
ordinate = [1:s(1)];
else
k = tan(angle);
hiX = round((1-(s(1)-y0+1)+k*x0)/k);
loX = round((s(1)-(s(1)-y0+1)+k*x0)/k);
temp = max(loX, hiX);
loX = max(min(loX, hiX), 1);
hiX = min(s(2),temp);
abscissa = [loX:hiX];
ordinate = k*abscissa+((s(1)-y0+1)-k*x0);
end
The lineBresenham function:
function [i] = lineBresenham(H,W,Sx,Sy,angle)
k = tan(angle);
if (angle == pi || angle == 0)
Ex = W;
Ey = Sy;
Sx = 1;
elseif (angle == pi/2)
Ey = 1;
i = (Sx-1)*H+[Ey:Sy];
return;
elseif k>0 & k < (Sy-1)/(W-Sx)
Ex = W;
Ey = round(Sy-tan(angle)*(Ex-Sx));
elseif k < 0 & abs(k) < (Sy-1)/(Sx-1)
Ex = 1;
Ey = round(Sy-tan(angle)*(Ex-Sx));
else
Ey = 1;
Ex = round((Sy-1)/tan(angle)+Sx);
end
Dx = Ex - Sx;
Dy = Ey - Sy;
iCoords=1;
if(abs(Dy) <= abs(Dx))
if(Ex >= Sx)
D = 2*Dy + Dx;
IncH = 2*Dy;
IncD = 2*(Dy + Dx);
X = Sx;
Y = Sy;
i(iCoords) = (Sx-1)*H+Sy;
iCoords = iCoords + 1;
while(X < Ex)
if(D >= 0)
D = D + IncH;
X = X + 1;
else
D = D + IncD;
X = X + 1;
Y = Y - 1;
end
i(iCoords) = (X-1)*H+Y;
iCoords = iCoords + 1;
end
else
D = -2*Dy + Dx;
IncH = -2*Dy;
IncD = 2*(-Dy + Dx);
X = Sx;
Y = Sy;
i(iCoords) = (Sx-1)*H+Sy;
iCoords = iCoords + 1;
while(X > Ex)
if(D <= 0)
D = D + IncH;
X = X - 1;
else
D = D + IncD;
X = X - 1;
Y = Y - 1;
end
i(iCoords) = (X-1)*H+Y;
iCoords = iCoords + 1;
end
end
else
Tmp = Ex;
Ex = Ey;
Ey = Tmp;
Tmp = Sx;
Sx = Sy;
Sy = Tmp;
Dx = Ex - Sx;
Dy = Ey - Sy;
if(Ex >= Sx)
D = 2*Dy + Dx;
IncH = 2*Dy;
IncD = 2*(Dy + Dx);
X = Sx;
Y = Sy;
i(iCoords) = (Sy-1)*H+Sx;
iCoords = iCoords + 1;
while(X < Ex)
if(D >= 0)
D = D + IncH;
X = X + 1;
else
D = D + IncD;
X = X + 1;
Y = Y - 1;
end
i(iCoords) = (Y-1)*H+X;
iCoords = iCoords + 1;
end
else
D = -2*Dy + Dx;
IncH = -2*Dy;
IncD = 2*(-Dy + Dx);
X = Sx;
Y = Sy;
i(iCoords) = (Sy-1)*H+Sx;
iCoords = iCoords + 1;
while(X > Ex)
if(D <= 0)
D = D + IncH;
X = X - 1;
else
D = D + IncD;
X = X - 1;
Y = Y - 1;
end
i(iCoords) = (Y-1)*H+X;
iCoords = iCoords + 1;
end
end
end
The vanishing point is at infinity hence the distance to the camera is of no use.
Use xlswrite or dlmwrite to write into excel or text file respectively.
I basically have a few variables
0 < na < 250
0 < max <= 16
nb = (na + max - 1) / max
n has the following characterstics
0 <= i < nb - 1 => n = max
i = nb - 1 => n = na - i * max
Is there an easy way to do this without the ternary operator?
for (i = 0; i<nb;i++) {
n = ((i + 1) * max > na ? na - (i * max) : max);
}
Examples
na = 5
max = 2
nb = 3
i = 0 => n = 2
i = 1 => n = 2
i = 2 => n = 1
na = 16
max = 4
nb = 4
i = 0 => n = 4
i = 1 => n = 4
i = 2 => n = 4
i = 3 => n = 4
na = 11
max = 3
nb = 4
i = 0 => n = 3
i = 1 => n = 3
i = 2 => n = 3
i = 3 => n = 2
The question is not very clear. Perhaps you're looking for something like this:
for (i=0;i < nb;++i)
{
n = i < nb - 1 ? max : (na - 1) % max + 1;
}
You don't need to calculate nb. This is one way you could do it (C#):
int na = 11;
int max = 4;
for (int i = 0, x = 0; x < na; i++, x += max)
{
int n = Math.Min(max, na - x);
Console.WriteLine("i = {0}, n = {1}", i, n);
}
Output:
i = 0, n = 4
i = 1, n = 4
i = 2, n = 3
Just to add more confusion to the thread:
If only you print max in the first two cases, then you could do something like: (not in any particular language)
//for 0
printf("i = %d, n = %d\n",i,max)
//for 1
printf("i = %d, n = %d\n",i,max)
//for the rest
for (i = 2; i<nb;i++) {
printf("i = %d, n = %d\n",i,na - (i * max));
}
You can avoid the operator doing two for loops
for (i = 0; (i + 1) * max) > na AND i < nb;i++) {
printf("i = %d, n = %d\n",i,0);
}
for (; i<nb;i++) {
printf("i = %d, n = %d\n",i,na - (i * max));
}