Check for incorrect argument data type or missing argument in call to function 'log'.

function [BrightImage] = Brightness(image , val)
[row , col, depth] = size(image);
BrightImage = zeros(row,col);
BrightImage = im2double(BrightImage);

for r = 1:row
    for c = 1:col
        BrightImage(r,c) = val * log(image(r,c) + 1);
    end
end
BrightImage = im2uint8(BrightImage);
end

[Jan]

What is your question? What are the inputs you provide to this function? Do you get an error message? Then please post a copy of the complete message.

This part looks strange:

BrightImage = zeros(row,col);
BrightImage = im2double(BrightImage);

BrightImage is a double matrix and with im2double you convert it to a double array, but this does not change anything.

What happens with the 3rd dimension depth?

You ran replace:

BrightImage = zeros(row,col);
BrightImage = im2double(BrightImage);
for r = 1:row
    for c = 1:col
        BrightImage(r,c) = val * log(image(r,c) + 1);
    end
end

by the much simpler:

BrightImage = val * log(image + 1);

but this does not change the error.

Answer 1

[Steven Lord]

I suspect your image variable (which you probably want to rename, as image already has a meaning in MATLAB) is one of the eight integer data types in MATLAB. The log function is not defined for any of the integer data types.

z = zeros('int8');
which -all log(z)

'log(z)' not found.

It is defined for double and single precision data as you can see from the code below.

d = 0;
which -all log(d)

built-in (/MATLAB/toolbox/matlab/elfun/@double/log)  % double method

s = 0;
which -all log(s)

built-in (/MATLAB/toolbox/matlab/elfun/@double/log)  % double method

If you were to try to call log on z then MATLAB will throw an error. [The exact error message appears to have changed between release R2021a and the current release.]

y = log(z)

Incorrect number or types of inputs or outputs for function 'log'.

Convert your data to double or single precision if you need to take its logarithm.