Not enough input arguments. Error in feature_extract3 (line 3) imdist=rgb2gray(imdist);

CODE :

function f = feature_extract3( imdist ,scale)
f=[];
imdist=rgb2gray(imdist);
weight=[0.2 0.8];
for i=1:scale
    im=imdist;
    fun0=@(x)secal(x);
    emat=blkproc(im,[8 8] ,fun0); 
    sort_t = sort(emat(:),'ascend');
    len = length(sort_t);
    t=sort_t(ceil(len*weight(1)):ceil(len*weight(2)));
    mu= mean(t);
    ske=skewness(sort_t);
    
    f1=[ mu  ske];
    im=imdist;
    fun1=@(x)fecal(x);
    im=double(im);
    femat=blkproc(im,[8 8],fun1);
    sort_t = sort(femat(:),'ascend');
    len = length(sort_t);
    t=sort_t(ceil(len*weight(1)):ceil(len*weight(2)));
    mu= mean(t);
    ske=skewness(sort_t);
    
    f2=[ mu  ske];
    f=[f f1 f2] ;
    
    imdist = imresize(imdist,0.5);
end
end

Q: This a code for feature extraction from the web, i am getting the error in rgb2gray function

[Dyuman Joshi]

You need to provide (the necessary) input(s) to a function to run it.

Answer 1

[Abhishek]

Hi @syeda,

Generally, MATLAB throws “not enough input arguments” error when a function is called with fewer input parameters than it requires to execute correctly.

The function ‘feature_extract3’ in the code shared requires two input arguments: ‘imdist’ and ‘scale’. However, only ‘imdist’ argument is being passed, which leads to the error.

To resolve the issue, pass the ‘scale’ parameter along with ‘imdist’ parameter when calling the function.

[DGM]

It's worth noting that the code will also throw an error if the image is not RGB. Inputs to rgb2gray() must be MxNx3. If there's a possibility that the input might already be grayscale, either test for it, or use im2gray() instead.

[Walter Roberson]

In order for this errror message to appear, imdist must not have been passed to the function -- the function is being called with no parameters at all. For example the function might have been invoked by pressing the green Run button instead of by calling it at the command line passing in appropriate parameters.