Matlab - perform a function of all matrix cells

Hello,

I have loaded a grayscale image into img so now I have a one matrix in it.

Now I used plot to show a graph of a function and I would like to use this function over all of the matrix values and actually change the gray values of the image.

I do know the "A(A>0) = value" function but I'm not sure how to use it with the plot I've made.

XData=get(get(gca,'children'),'XData'); 
YData=get(get(gca,'children'),'YData'); 
% Get y value for x=3.33 - NOT a data point. 
y_3p33 = interp1(XData,YData,3.33,'spline')

(c) paulo silva http://www.mathworks.com/matlabcentral/answers/1353 so this is actually the way of getting the new Y point for each value but how can I use it over all the matrix cells in a fast way? (actually in any way)

thank you!

[Jan]

Please use meaningful tags. Obviously all questions in thius forum concern "matlab code".

Do you mean "matrix elements"? "Cells" are a special type of arrays, which can contain elements of different types.

Answer 1

[Jan]

Please use meaningful tags. Obviously all questions in thius forum concern "matlab code".

Do you mean "matrix elements"? "Cells" are a special type of arrays, which can contain elements of different types.

I do not see the connection between the XData and YData of your graph and the loaded image. What exactly is a "one matrix"? Are you looking for:

A2 = reshape(interp1(XData,YData, A(:), 'spline'), size(A));

Answer 2

[Despairy]

img=imread('filename');

so img now holds a matrix (the file is a grayscale image) of the gray values of the image.

now I have a plotted function on axes1

lets say f(100)=20
and f(250)=50

so now I want the gray values to change according to the function plotted from what I read about the reshape function it is not exactly what I'm lookin for.

actually what I want is the following to happen

A(A=100)=20
A(A=250)=50

but for all of the values between 0 and 255 using the function plotted.

thanks for your help