how can i change the value of red in a pixel in a photo?

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amira hl 2015-6-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222759-how-can-i-change-the-value-of-red-in-a-pixel-in-a-photo

编辑： Walter Roberson 2015-6-6

采纳的回答： Image Analyst

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hi voici le code

clc; clear all; close all;  
im=imread('photo.jpg');  
b=1;  
delta=20;  
wi=0  
l=impixel(im,1,5);  
f=l(1)  
m=floor(f/((2^b)*delta));  
r=f-(2^b)*m*delta;  
f1=(2^b)*m*delta+wi*delta+r/(2^b)  
impixel(im,1,5)(1)=f1

le dernier ligne a généré cette erreur

??? Error: File: Untitledtest.m Line: 14 Column: 1

()-indexing must appear last in an index expression.

comment faire pour changer un seul valeur parmi le 3 valeurs dans un pixel choisi??

merci

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采纳的回答

Image Analyst 2015-6-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222759-how-can-i-change-the-value-of-red-in-a-pixel-in-a-photo#answer_181791

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You cannot do this:

impixel(im,1,5)(1)=f1

If you want to set row 1, column 5 of image im to a value of f1, you need to do this:

im(1, 5) = f1;

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amira hl 2015-6-6

编辑：Walter Roberson 2015-6-6

在 MATLAB Online 中打开

clc; clear all; close all;
im=imread('photo.jpg');
l=impixel(im,1,5)
im(1,5,1)=10;
impixel(im,1,5)
executing =>
l =
     232   239   255
ans =
     232   239   255

nothing change

Image Analyst 2015-6-6

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You need to make sure whether you're dealing with x,y or row, column. Looking at the help to make sure.....

% Read in RGB image.
im = imread('peppers.png');
% Define a row and column.
c = 1;
r = 5;
% Check value of image at row 5, column 1.
rgbValues1 = impixel(im, c, r)
im(r,c,1)=10;
rgbValues2 = impixel(im, c, r)

You get:

rgbValues1 =
    63    31    62
rgbValues2 =
    10    31    62

Note, impixel takes x,y (which is the same as col, row), whereas indexing an array is always row, col. So you need to make sure you're using the right form (order) in the right place.

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