Trivalent samarium (Sm3+) doped Na3Gd(PO4)2 (NGP) phosphors were prepared by citrate gel combustion process. The structure, optical and energy transfer studies were systematically characterized through photoluminescence (PL), X- ray diffraction, and decay measurements, respectively. Upon 406 nm excitation Sm3+ doped NGP phosphors emit orange-red luminescence with peak maximum at 602 nm. Sm3+ ions were located at the inversion symmetry sites of NGP lattice. The Commission International de I’Eclairage chromaticity coordinates were calculated from the photoluminescence spectra. The NGP: Sm3+ phosphors can be used as a promising material for solid state lighting devices.

Retrieving the image based on the content is one of the most significant research fields in the digital image processing area. The image retrieval is becoming an innovative and quickest way of retrieving the image. Many digital images and videos are uploaded and transitioned everyday, because of the social networking medium development. Google, Yahoo and many search engines are accessing the large collection of database based on the textual annotation. These images are annotated manually with keywords, descriptions and then the images are retrieved using text-based searching methods. Therefore, performances of these systems are not satisfactory. So, we need new techniques. These techniques will easy to handle the data and can easily access the data. The CBIR method is working on the basis of particular image feature such as color, texture and shape which are derived automatically. It uses digital processing and analysis to automatically generate descriptions directly from the media data. This paper represents how the implementation of image retrieval is done based on the content.