A. Vadivel, M. Mohan, Shamik Sural and A. K. Majumdar SEGMENTATION USING SATURATION THRESHOLDING AND ITS APPLICATION IN CONTENT-BASED RETRIEVAL OF IMAGES A. Vadivel, M. Mohan, Shamik Sural and A. K. Majumdar INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR, INDIA. shamik@sit.iitkgp.ernet.in

ANALYSIS OF THE HSV COLOR SPACE Three dimensional representation of the HSV color space Central vertical axis represents intensity, I Hue, H, is an angle in the range [0,2p] relative to the red axis. Saturation, S, is the depth or purity of color 11/11/2018 Indian Institute of Technology, Kharagpur

VISUAL PERCEPTION IN THE HSV COLOR SPACE (b) Variation of color perception with (a) saturation (Decreasing from 1 to 0 right to left) for a fixed value of intensity and (b) intensity (Decreasing from 255 to 0 right to left) for a fixed value of saturation. 11/11/2018 Indian Institute of Technology, Kharagpur

SATURATION THRESHOLDING Use Saturation of a Pixel to Determine Hue or Intensity is more pertinent to Human Visual Perception Ignore Actual Value Saturation Image pixels from a distribution of “colors” “gray color” and “true color” Threshold to determine a “true color” and a “gray color” pixel: thsat(V) = 1.0 – (0.8V/255) 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur IMAGE REPRESENTATION Each image is represented as a collection of pixel features I{(pos, [t|g], val)} val [0,2p] if [t|g] takes a value of t and val [0,255] if [t|g] takes a value of g. Approximation occurs as shown below (a) (b) (c) (d)   (a) Original Image (b) HSV Approximation (c) RGB approximation with all low order bits set to 0 and (d) RGB approximation with all low order bits set to 1. 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur IMAGE SEGMENTATION Pixel Grouping by K-means Clustering Algorithm I {O1|O2|O3|….|On} Oi([t|g], val, {pos}) Each partition represents either a “true color” value or a “gray color” value Consists of the positions of all the image pixels that have colors close to val. Post Processing Connected Component Analysis Filtering Merging 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur DIFFERENT STAGES OF IMAGE SEGMENTATION (a) (b) (c) (d) (a) Original image (b) Image after clustering (c) Image after connected component analysis and (d) Final segmented Image 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur IMAGE SEGMENTATION RESULTS Natural Scene Images 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur IMAGE SEGMENTATION RESULTS – CONTD. Miscellaneous Images 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur WEB BASED IMAGE RETRIEVAL APPLICATION Query Specification By Example Image Display of Result Set Nearest Neighbor Retrieval External Image Upload Utility to Upload External Image Files 11/11/2018 Indian Institute of Technology, Kharagpur

Relevant Set is not known for Large Uncontrolled Data Sets PERFORMANCE MEASURE Recall = Precision = Relevant Set is not known for Large Uncontrolled Data Sets Perceived Precision = 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur RESULTS Precision vs. recall on a controlled database of 2,015 images Perceived precision variation on a large un-controlled database of 28,168 images 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur CONCLUSIONS AND FUTURE WORK Effective way to capture Pixel Color Information using the HSV Color Space Relative importance of Hue and Intensity determined based on Saturation Pixel represented as True Color or Gray Color Clustering of Image Pixels for Segmentation Post-processing Web-based Image Retrieval System Perceived Precision for Testing on Large Data Sets More Experiments and Comparative Studies being Carried out New Distance Metrics 11/11/2018 Indian Institute of Technology, Kharagpur

Indian Institute of Technology, Kharagpur Thank You 11/11/2018 Indian Institute of Technology, Kharagpur