The present invention relates to methods and apparatus for identifying features in an image. More particularly, but not exclusively, the present invention relates to methods and apparatus for fitting models to an image to identify features in the image.
Automated image analysis may be used to reduce manual workloads in determining properties of images. Image analysis is used in a variety of different fields to identify features of images. One area in which image analysis techniques are used is to process medical images where the identification of anatomical features in an image can provide useful information to medical practitioners. Often many images are required to be processed, for example in a screening program, and each image should be processed as accurately as possible.
Images of a particular anatomical feature obtained from different patients vary considerably. This may particularly be the case when an anatomical feature is in a diseased state. It can therefore be difficult to accurately identify anatomical features in images given such variance. An existing approach to identifying anatomical features in an image is based upon statistical modelling of an anatomical region of interest. Statistical models are generated from a training set of images in which features within the anatomical region of interest have been manually identified and a statistical model indicates a mean model and an acceptable degree of variation from the mean model, as indicated by the training set. Where a small number of training images are available, a statistical model can often fail to identify particular anatomical features in previously unseen images due to the failure of the statistical model to capture a true indication of acceptable variation.
Additionally, existing approaches for fitting statistical models to previously unseen images can be inaccurate, particularly when an anatomical feature is in a diseased state in the previously unseen image. A robust and accurate method of modelling structures in images and fitting such models to previously unseen images is therefore desirable.
It is an object of some embodiments of the present invention to obviate or mitigate at least some of the problems set out above.