Artifacts appear on my matlab image

Question

Tina 2024-8-20

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2146619-artifacts-appear-on-my-matlab-image

评论： Tina 2024-8-23

Hello everyone,

I wrote a matlab program to process my data, the results and in the form of image of different colors. The color scale is a choice and this is the problem, because when I use a colormap with 3 different colors I don't have this artifact that appears but when I use the one with the rainbow colors the artifact appears. I'm attaching the image and the code snippet for the colormap. Do you have any idea why I'm having this problem? How can I fix it?

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Cris LaPierre 2024-8-20

编辑：Cris LaPierre 2024-8-20

在 MATLAB Online 中打开

k = [0 0 0]; %# start

p = [1 0 1];

n = [0 0 1];

b = [0 1 1];

g = [0 1 0]; %# middle

y = [1 1 0];

r = [1 0 0];

z = [0 0 0];%# end

% Colormap de taille 64x3, dégradée en arc-en-ciel

cl = zeros (32,3); c2 = zeros (32,3); c3 = zeros (32,3); c4 = zeros (32,3);

c5 = zeros (32,3); c6 = zeros (32,3); c7 = zeros (32,3);

for i = 1:3

cl(:,i) = linspace (k(i), p(i), 32);

c2(:,i) = linspace (p(i), n(i), 32);

c3(:,i) = linspace (n(i), b(i), 32);

c4(:,i) = linspace (b(i), g(i), 32);

c5(:,i) = linspace (g(i), y(i), 32);

c6(:,i) = linspace (y(i), r(i), 32);

c7(:,i) = linspace (r(i), z(i), 32);

end

% Combinaison de toutes les parties sans doublons

c = [cl(1:end-1,:); c2(1:end-1,:); c3(1:end-1,:); c4(1:end-1,:); c5(1:end-1,:); c6(1:end-1,:); c7];

% Afficher la surface

surf (peaks), shading interp

caxis([-1 1])

colormap(c)

colorbar

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Answer 1

Cris LaPierre 2024-8-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2146619-artifacts-appear-on-my-matlab-image#answer_1501814

We'd have to see your code for 3 colors to say for certain, but here, your colormap sets anything above or below abs(1) to [0 0 0], or black. We don't have your processed data, but it would appear the region of the artifact must contain absolute values >= 1.

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Tina 2024-8-20

编辑：Walter Roberson 2024-8-20

在 MATLAB Online 中打开

I've commented on the absolute value as you can see from the photo, but the problem persists.

For the colormaps code which contains only 3 colors (in reality we have 5 colors with two blue and two red), here it is at the bottom, you can see on the result picture that in this case I don't have an artifact even though it's the same data.

%----------------------------------------------------------------------------------bleu-blanc-rouge----------------------------
B = [0.0840 0.1747 0.3910];   %# start
b = [0 0 1];     
g=[0.8290,0.8940, 0.0250];  %# middle
r = [1 0 0];      
R = [0.6350 0.0780 0.1840];       %# end
%colormap of size 64-by-3
c1 = zeros(32,3); c2 = zeros(32,3);c3 = zeros(32,3);c4 = zeros(32,3);
for i=1:3
    c1(:,i) = linspace(B(i), b(i), 32);
    c2(:,i) = linspace(b(i), g(i), 32);
    c3(:,i) = linspace(g(i), r(i), 32);
    c4(:,i) = linspace(r(i), R(i), 32);
end
c = [c1(1:end-1,:);c2;c3;c4];
%surf(peaks), 
shading interp
caxis([-1 1])
colormap (c)
%--------------------------------------------------------------------------------

Cris LaPierre 2024-8-20

在 MATLAB Online 中打开

V.mat

Here is my best guess at what you may be doing. Note that it does not show the artifact. The code you have not shared must be doing something additional to the data that is causing the artifact to appear.

load V.mat

surf(X,Y,V1,'LineStyle','none')

view(2)

%----------------------------------------------------------------------------------bleu-blanc-rouge----------------------------

B = [0.0840 0.1747 0.3910]; %# start

b = [0 0 1];

g=[0.8290,0.8940, 0.0250]; %# middle

r = [1 0 0];

R = [0.6350 0.0780 0.1840]; %# end

%colormap of size 64-by-3

c1 = zeros(32,3); c2 = zeros(32,3);c3 = zeros(32,3);c4 = zeros(32,3);

for i=1:3

c1(:,i) = linspace(B(i), b(i), 32);

c2(:,i) = linspace(b(i), g(i), 32);

c3(:,i) = linspace(g(i), r(i), 32);

c4(:,i) = linspace(r(i), R(i), 32);

end

c = [c1(1:end-1,:);c2;c3;c4];

% surf(peaks),

shading interp

caxis([-1 1])

colormap(c)

colorbar

%----------------

figure

surf(X,Y,V1,'LineStyle','none')

view(2)

k = [0 0 0]; %# start

p = [1 0 1];

n = [0 0 1];

b = [0 1 1];

g = [0 1 0]; %# middle

y = [1 1 0];

r = [1 0 0];

z = [0 0 0];%# end

% Colormap de taille 64x3, dégradée en arc-en-ciel

cl = zeros (32,3); c2 = zeros (32,3); c3 = zeros (32,3); c4 = zeros (32,3);

c5 = zeros (32,3); c6 = zeros (32,3); c7 = zeros (32,3);

for i = 1:3

cl(:,i) = linspace (k(i), p(i), 32);

c2(:,i) = linspace (p(i), n(i), 32);

c3(:,i) = linspace (n(i), b(i), 32);

c4(:,i) = linspace (b(i), g(i), 32);

c5(:,i) = linspace (g(i), y(i), 32);

c6(:,i) = linspace (y(i), r(i), 32);

c7(:,i) = linspace (r(i), z(i), 32);

end

% Combinaison de toutes les parties sans doublons

c = [cl(1:end-1,:); c2(1:end-1,:); c3(1:end-1,:); c4(1:end-1,:); c5(1:end-1,:); c6(1:end-1,:); c7];

% Afficher la surface

caxis([-1 1])

colormap(c)

colorbar

Tina 2024-8-21

编辑：Cris LaPierre 2024-8-21

在 MATLAB Online 中打开

Here is my entire code, i use the txt file 'index' for the triangle contour.

Thanks again for your help.

%% Edit to run code here

load V.mat

index = readmatrix('Au_Triangle_Index.txt');

x = X;

y = Y;

k = [0 0 0]; %# start

p = [1 0 1];

n = [0 0 1];

b = [0 1 1];

g = [0 1 0]; %# middle

yy = [1 1 0];

r = [1 0 0];

z = [0 0 0];%# end

% Colormap de taille 64x3, dégradée en arc-en-ciel

cl = zeros(32,3); c2 = zeros(32,3); c3 = zeros(32,3); c4 = zeros(32,3);

c5 = zeros(32,3); c6 = zeros(32,3); c7 = zeros(32,3);

for i = 1:3

cl(:,i) = linspace (k(i), p(i), 32);

c2(:,i) = linspace (p(i), n(i), 32);

c3(:,i) = linspace (n(i), b(i), 32);

c4(:,i) = linspace (b(i), g(i), 32);

c5(:,i) = linspace (g(i), yy(i), 32);

c6(:,i) = linspace (yy(i), r(i), 32);

c7(:,i) = linspace (r(i), z(i), 32);

end

% Combinaison de toutes les parties sans doublons

c = [cl(1:end-1,:); c2(1:end-1,:); c3(1:end-1,:); c4(1:end-1,:); c5(1:end-1,:); c6(1:end-1,:); c7];

%%---------------------------------------------------------------------------

figure % Complete

hold all

pcolor(X,Y,V1)

contour(x,y,real(index'),'linecolor','G');

colorbar

%box on

AX=gca;

AX.LineWidth=2;

AX.FontSize=14;

AX.TickLength=[0.02 0.02];

AX.XTick=-300:150:300;

AX.YTick=-300:150:300;

axis tight

%xlabel('X position (nm)','Fontsize',18,'FontWeight','bold')

%ylabel('Y position (nm)','Fontsize',18,'FontWeight','bold')

axis equal

%axis([-160-Rod_Width-Gap_Width/2,160+Rod_Width+Gap_Width/2,-160-Rod_Length+Gap_Length/2,160+Rod_Length-Gap_Length/2])

%axis([-40-Rod_Width-Gap_Width/2,40+Rod_Width+Gap_Width/2,-150-Rod_Length+Gap_Length/2,150+Rod_Length-Gap_Length/2])

colorbar

CA=caxis;

CB=colorbar;

CB.LineWidth=1;

CB.FontSize=14;

CB.Ticks=-10:1:10;

CB.Label.String='V';

CB.Label.FontSize=18;

CB.Label.FontWeight='bold';

figure % Axis only

colormap (c)

shading interp

box on

AX=gca;

AX.LineWidth=2;

AX.FontSize=14;

AX.TickLength=[0.02 0.02];

AX.XTick=-300:150:300;

AX.YTick=-300:150:300;

%xlabel('X position (nm)','Fontsize',18,'FontWeight','bold')

%ylabel('Y position (nm)','Fontsize',18,'FontWeight','bold')

%axis equal

%axis([-80-Rod_Width-Gap_Width/2,80+Rod_Width+Gap_Width/2,-80-Rod_Length+Gap_Length/2,80+Rod_Length-Gap_Length/2])

%axis([-40-Rod_Width-Gap_Width/2,40+Rod_Width+Gap_Width/2,-150-Rod_Length+Gap_Length/2,150+Rod_Length-Gap_Length/2])

axis tight

colorbar

caxis(CA);

CB=colorbar;

CB.LineWidth=1;

CB.FontSize=14;

CB.Ticks=-10:1:10;

CB.Label.String='V';

CB.Label.FontSize=18;

CB.Label.FontWeight='bold';

Tina 2024-8-21

编辑：Cris LaPierre 2024-8-21

在 MATLAB Online 中打开

figure

index=dlmread('Au_Triangle_Index.txt');

%% Edit so that code runs here

load V.mat

x = X; y = Y;

% [X,Y]=meshgrid(x,y);

%% -----------------------------------------

hold all

contour(x,y,real(index'),'linecolor','G');

surf(X,Y,V1,'LineStyle','none')

view(2)

k = [0 0 0]; %# start

p = [1 0 1];

n = [0 0 1];

b = [0 1 1];

g = [0 1 0]; %# middle

y = [1 1 0];

r = [1 0 0];

z = [0 0 0];%# end

% Colormap de taille 64x3, dégradée en arc-en-ciel

cl = zeros (32,3); c2 = zeros (32,3); c3 = zeros (32,3); c4 = zeros (32,3);

c5 = zeros (32,3); c6 = zeros (32,3); c7 = zeros (32,3);

for i = 1:3

cl(:,i) = linspace (k(i), p(i), 32);

c2(:,i) = linspace (p(i), n(i), 32);

c3(:,i) = linspace (n(i), b(i), 32);

c4(:,i) = linspace (b(i), g(i), 32);

c5(:,i) = linspace (g(i), y(i), 32);

c6(:,i) = linspace (y(i), r(i), 32);

c7(:,i) = linspace (r(i), z(i), 32);

end

% Combinaison de toutes les parties sans doublons

c = [cl(1:end-1,:); c2(1:end-1,:); c3(1:end-1,:); c4(1:end-1,:); c5(1:end-1,:); c6(1:end-1,:); c7];

% Afficher la surface

caxis([-1 1])

colormap(c)

colorbar

%box on

AX=gca;

AX.LineWidth=2;

AX.FontSize=14;

AX.TickLength=[0.02 0.02];

AX.XTick=-300:150:300;

AX.YTick=-300:150:300;

axis tight

%xlabel('X position (nm)','Fontsize',18,'FontWeight','bold')

%ylabel('Y position (nm)','Fontsize',18,'FontWeight','bold')

axis equal

%axis([-160-Rod_Width-Gap_Width/2,160+Rod_Width+Gap_Width/2,-160-Rod_Length+Gap_Length/2,160+Rod_Length-Gap_Length/2])

%axis([-40-Rod_Width-Gap_Width/2,40+Rod_Width+Gap_Width/2,-150-Rod_Length+Gap_Length/2,150+Rod_Length-Gap_Length/2])

colorbar

CA=caxis;

CB=colorbar;

CB.LineWidth=1;

CB.FontSize=14;

CB.Ticks=-10:1:10;

CB.Label.String='V';

CB.Label.FontSize=18;

CB.Label.FontWeight='bold';

Cris LaPierre 2024-8-21

Great to hear. I've edited your post so that your code runs here as well, showing no artifact.

Tina 2024-8-23

Thank you very much for your invaluable help.

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Artifacts appear on my matlab image

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