使用rgb2ind时未定义的变量

Question

I have this simple program where I'm trying to set the number of colors of an image to 1000, but I get the following error: Undefined function or variable 'rgb'. I also tried with uppercase and quotes, although in the examples I found there where no quotes. I am using Matlab R2012a.

clc
clear all

rgbImage = imread('peppers.png');
[rgbImage,map]=rgb2ind(RGB,1000);

Answer 1

The variable you're using as the first parameter to rgb2ind is wrong. You need to do:

[rgbImage, map] = rgb2ind(rgbImage, 1000);

My guess is that you consulted the MATLAB documentation on rgb2ind and you literally took the first parameter to be substituted as RGB . The documentation clearly says that RGB is an image loaded into MATLAB. This is not a constant.