How do I transform an image to have different dimensions

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image-processing

I want to write code that does the following:

Inputs:
An image of a fully clothed human being (assume from head to toe)
Dimensions of the human in that image (bust, waist, hips, height)
Target dimensions (bust, waist, hips, height)

Outputs:
Transformed image which is just like original image but human being now has the target dimensions.

Does anyone know how to do this transformation? I am guessing that I need 2 pattern recognition algorithms. The first one to detect the human in the picture and the second one to transform the human to another shape.