logarithmic plot function failure
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Hello,
After reading a certain article connected to pseudocoloring a grey image with HSI map color I wanted to try it on my own but the result didnt meet my expectations, the problem is logarithmic function. Article states that impying these formulas:
I should get plot:
my code:
map = zeros(256,3);
x = 1:256;
map(:,1) = 1/2 - 1/2*sqrt(1 - (x/256).*(x/256));
map(:,2) = 0.8;
map(:,3) = log(((x+1)/(256+1)));
figure;plot(x,map);
回答（1 个）
Jan
2019-1-4
Where do you see a failure? If the argument of the logarithm is smaller then e (which is exp(1)), the output must be negative. In the posted diagram I (the blue line) starts at 0, while this is not possible for:
log((x+1) / (256 + 1))
So the actuial problem is, that your expectations do not match the posted formula.
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