Editing Content-based image retrieval (section)

===Shape===
Shape does not refer to the shape of an image but to the shape of a particular region that is being sought out.  Shapes will often be determined first applying [[Segmentation (image processing)|segmentation]] or [[edge detection]] to an image.  Other methods use shape filters to identify given shapes of an image.<ref>{{cite book | last=Tushabe | first=F. |author2=M.H.F. Wilkinson | title=Advances in Multilingual and Multimodal Information Retrieval | chapter=Content-Based Image Retrieval Using Combined 2D Attribute Pattern Spectra | volume=5152 | pages=554–561 | year=2008| doi=10.1007/978-3-540-85760-0_69 | series=Lecture Notes in Computer Science | isbn=978-3-540-85759-4 | s2cid=18566543 | url=https://pure.rug.nl/ws/files/2720522/2008LNCSTushabe.pdf }}</ref>  Shape descriptors may also need to be invariant to translation, rotation, and scale.<ref name="Rui"/>

Some shape descriptors include:<ref name="Rui"/>
* [[Fourier transform]]
* [[Image moment|Moment invariant]]