how to create 2D polynomial regression?

hi I have a 22x34 image. how to create a function just like ax^2+by^2+cxy+dx+ey+f to fit this image

Answer 1

[dpb]

If have CurveFitting Toolbox,

sf = fit([x, y], z, 'poly22');  % doc fit for details...

If not, write the specific model matrix and use \ to solve.

doc mldivide % illustrates

Oh, or if have Statistics Toolbox, there's the regress linear regression method.

[chien-feng Huang]

thank you

Answer 2

[Image Analyst]

You can use John D'Errico's polyfitn in the File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/34765-polyfitn.

Attached is an example of how I used it to correct (flatten) a background.