and i want to detect an elipse in it and measure its axes. all i was able to do is convert image to binary and using close- i got rid of most of noise.
The best way to do what you want is to use the Gaussian Bivariate Ellipse fitting technique. You can find the details in any good statistics textbook or on the internet. You'll probably have to write a plug-in. When the technique is applied to the type of data you show in this post, it will output the data you need to draw a fitting ellipse including center point (X,Y) major and minor axes (a and b) and the long angle of the ellipse.