I want to read images from a gallery contain 20 color images and then convert these to gray scale images and finding histogram for each,how can I do it? making index for every image!!!

clc
for i=1:20
g(i)=imread(D:\Master\Research\Practical-Matlab\1\m.jpg');%gallery images
f(i)=rgb2gray(g(i));
end

Answer 1

[Joseph Cheng]

you'll have to do something like this:

yourgalleryfolder = 'D:\Master\Research\Practical-Matlab\1\';
imagefiles = dir(fullfile(yourgalleryfolder,'*.jpg'));
Images = struct('data',[],'histogram',[]);
for ind = 1:numell(imagefiles)
    Images(ind).data = imread(fullfile(yourgalleryfolder,imagefiles(ind).name));
    Images(ind).histogram = hist(Images(ind).data);   
end

[Batool Engineer]

thank you, but here I have an error, appear down: Undefined function 'numell' for input arguments of type 'struct'.

Error in ppp1 (line 6) for ind = 1:numell(imagefiles)

[Stephen23]

The correct function name is numel, exactly as any internet search engine would have told you.