find perceptual similarity between two images in java

I'm looking for an algorithm that can find perceptual similarity between two images, actually i want to input one picture into system and it search whole my database which contain huge amount of picture and then retr开发者_如何学Cieve the images which have more perceptual similarity with source image, could any body please help me ?

I mean i want to find similar pic. i heard some algorithm can find similar pictures base on the source pic's shape, color and etc (pixel by pixel). i wanna have the system that i input the source image and system retrieve the similar images based on perceptual features like shape, color, size and etc.

Thanks

You need to define carefully what 'perceptually similar' means to you, before trying to find a measurable entity that captures that. Imagine a picture of of a grass field under a blue sky with a horse. Should your application retrieve all horse pictures? Or all pictures with green grass and a blue sky? In the latter case, the above mentioned color histograms are a good start. Alternatively you could look at gaussian mixture models (GMM), they are used quite a bit in retrieval. This code could be a starting point and this article Image retrieval using color histograms generated by Gauss mixture vector quantization

More complicated is the so called "bag of words" or "visual words" approach. It is increasingly used for image categorization and identification. This algorithm usually starts by detecting robust points in an image, meaning that these points will survive certain image distortions. Example popular algorithms are SIFT and SURF. The region around these found points is captured with a descriptor, which could for example be a smart histogram.

In the most simple form, one can collect all data from all descriptors from all images and cluster them, for example using k-means. Every original image then has descriptors that contribute to a number of clusters. The centroids of these clusters, i.e. the visual words, can be used as a new descriptor for the image. The VLfeat website contains a nice demo of this approach, classifying the caltech 101 dataset. Also noteworthy, are results and software from Caltech itself.

One simple way to start is comparing the Color Histogram.

But the following article proposes the use of Joint Histogram instead. You may also take a look.

http://www.cs.cornell.edu/rdz/joint-histograms.html