increase of efficiency for manipulating image pixels

hello guys, i have two arrays of pixels coordinates witch i'd like to change their value,one contains rows (named R) the other columns (named C) this instruction: image(R(:),C(:))=new value; doesn't result in what i want and i have to use two for loops. do you know any more efficient way to achieve this goal? thank you in advance

[Ashish Uthama]

http://www.mathworks.com/matlabcentral/answers/11082-how-do-i-index-into-a-2d-matrix-using-two-equal-length-r-and-c-vectors

Answer 1

[Walter Roberson]

image(sub2ind(size(image),R,C)) = newvalue;

See sub2ind