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Improved Color Descriptor for Image Retrieval in MPEG-7 using Merged Palette Histogram Similarity Measure

A novel approach utilizing Merged Palette Histogram Similarity Measure (MPHSM) to enhance the dominant color descriptor (DCD) in MPEG-7 for image retrieval. MPHSM redefines query histograms based on a common color space, enabling identification of identical and similar colors while measuring similarity based on area matching. Experimental results demonstrate significant improvement over existing methods, with potential for further enhancement. Visit the link for a demo.

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Improved Color Descriptor for Image Retrieval in MPEG-7 using Merged Palette Histogram Similarity Measure

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  1. MPEG-7 DCD using Merged Palette Histogram Similarity Measure Lai-Man Po and Ka-Man Wong ISIMP 2004 Oct 20-22, Poly U, Hong Kong Department of Electronic Engineering City University of Hong Kong

  2. A compact and effective descriptor Generated by GLA color quantization Maximum of 8 colors in storage MPEG-7 Dominant Color Descriptor

  3. Percentage p color Percentage q color Dominant Color Descriptor • Similarity measure • A modified Quadratic Histogram Distance Measure (QHDM) • Since each DCD may have different set of colors, QHDM is used to account for identical colors and similar colors.

  4. F 1/3 3 I I I I 2 3 1 1 1/2 1/2 1/2 F F F 2 1 1 DCD-QHDM upper bound problem • Limitations of QHDM - 1 • Distance upper bound is varied by number of matching colors • Completely different image cannot be identified by its upper bound

  5. DCD-QHDM upper bound problem • Analysis of problem 1 • The upper-bound of the distance measured varies by number of color in the descriptor • Maximum of positive part is not a constant • Maximum of negative part is zero • So, the maximum of QHDM result is not fixed • This property makes DCD unable to identify completely different images by the values measured Positive part Negative part

  6. I I I I 2 1 1 4 1 1/2 1/2 1/2 F F F F 2 1 1 4 DCD-QHDM Similarity coefficient problem • Limitations of QHDM - 2 • The similarity coefficient does not well model color similarity • It does not balance between color distance and area of matching

  7. T d d a = 1.2 a = 44% a = 16.67% a = 0% DCD-QHDM Similarity coefficient problem • The similarity coefficient use the color distance to fine tune the similarity • Difficult to define a quantitative similarity between colors, • Sensitivity of human eye depends on many conditions (e.g. light source of the room, spatial layout of the image, etc.)

  8. Common Palette Proposed Merged Palette Histogram Similarity Measure • MPHSM Process - 1 • Find the closest pair of colors using Euclidian distance in CIELuv color space • MPHSM process - 2 • If the distance smaller than a threshold Td, merge them to form a new common palette color

  9. Common Palette Merged Palette Histogram Dominant Color Descriptor Proposed Merged Palette Histogram Similarity Measure • MPHSM process - 3 • A new common palette is then generated • Form new descriptors based on the common palette

  10. Proposed Merged Palette Histogram Similarity Measure • MPHSM process - 4 • Histogram intersection is used to measure the similarity • Count the non-overlapping area as the distance

  11. Initial DCDs Step 1: Find a pair of colors with minimum distance d d<Td ? Step2: Merge colors having minimum distance Y N Common Palette Step 3: Update each DCD based on the common palette Step 4: Histogram Intersection Flow of MPHSM

  12. Experiment Result of MPH-RF • Experiment Methodology • ANMRR • Image Database • 5466 Images from MPEG-7 common color dataset (CCD) • 50 Pre-defined query and ground truth sets

  13. Latest experimental results • MPHSM without spatial coherence improves DCD by about 0.04 of ANMRR in average • Very close to QHDM with spatial coherence • Significant improve in medium queries • It gives significant improvement on visual results *ANMRR (smaller means better)

  14. Experimental results • Visual results - Query #32 from MPEG-7 CCD • Demo available in http://www.ee.cityu.edu.hk/~mirror/ Query image QHDM results, ANMRR=0.4 MPHSM result, ANMRR=0.0111

  15. Experimental results • Visual results - Query #25 from MPEG-7 CCD • Demo available in http://www.ee.cityu.edu.hk/~mirror/ Query image QHDM results, ANMRR=0.3935 MPHSM result, ANMRR=0.0481

  16. Conclusion • A new merged palette histogram similarity measure for dominant color descriptor of MPEG-7 is proposed • The merged palette formed a common color space and used to redefine the new query histograms for histogram intersection similarity measure. • Can matchidentical colors as well as similar colors • Use area of matching for similarity measure

  17. Conclusion • Experimental results show that the proposed MPHSM improve DCD-QHDM using ANMRR rating by about 0.04 and very close to the result of DCD-QHDM with spatial coherence • Our experiment result also found that the result of proposed method can be further improved by spatial coherence • The proposed method also provide better perceptually relevant image retrieval.

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