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

9 views (last 30 days)
amira hl on 6 Jun 2015
Edited: Walter Roberson on 6 Jun 2015
hi voici le code
clc; clear all; close all;
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

Image Analyst on 6 Jun 2015
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;
Image Analyst on 6 Jun 2015
You need to make sure whether you're dealing with x,y or row, column. Looking at the help to make sure.....
% 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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