logarithmic plot function failure

1 次查看（过去 30 天）
iMatten
iMatten 2019-1-3
评论： iMatten 2019-1-4
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);

请先登录，再回答此问题。

回答（1 个）

Jan
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.
  1 个评论
iMatten
iMatten 2019-1-4
yes, I agree with that. I was wondering if there is any trouble with formula or I was doing something wrong.
I hadn't thought that might be a mistake in this article. Then what formula for "I: component that would be?

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Blue 的更多信息

标签

产品


版本

R2018a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by