On 10/22/2013 03:54 PM, Ankit Agrawal wrote:
> Hi Jim,
>
>          What Joe said is correct when you want to label/classify images, 
> since classifying images by trying to find similarity of the test image with 
> the training images on pixel level would not work even if there is some 
> ordinary geometric transform like scaling or rotation or Intensity changes. 
> This is where Feature Detection and Feature Description algorithms mentioned 
> above come into play. I have implemented a few of them in scikit-image as 
> part of this year's GSoC, though some of them are not yet merged. OpenCV's 
> feature2d module is very comprehensive in such algorithms.
>
>
>          From your description, it seems you want to label each pixel and 
> hence extracting on a features pixel by pixel basis is a better way to go. 
> Depending on your data, the feature vector used to describe every pixel might 
> depend on values/properties of its neighbouring patch say 5 x 5.It is not 
> clear whether you have a labelled training data. If you do, you will need to 
> describe each pixel(i.e. data point) using a feature vector that is 
> discriminates well between different labels and is similar for pixels 
> belonging to the same label. You will have to use the information about the 
> dataset to figure out what features might be appropriate to describe each 
> pixel. If you don't have a labelled dataset, this turns into clustering 
> problem, where the features you choose for representing a pixel will depend 
> on the motivation for clustering.
>
>          
>          Another good free resource for Computer Vision 
> ishttp://szeliski.org/Book/
>
>          Hope this helps. Thanks.
>
Whoops I only say your mail after writing mine ;)

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