Zernike Moments-Based Gurumukhi Character Recognition

Figures & data

Figure 1. Inner circle mapping approach in which an image is mapped onto the unit circular disk.

Figure 2. Inscribed circular disk approximated by square grids.

Figure 3. Outer circle mapping approach in which an image is mapped entirely within the unit circular disk.

Figure 4. Sample images from Gurumukhi character dataset.

Table 1. Recognition rates (%) obtained on GC-s dataset using both mapping techniques.

	Binary images		Grayscale images
Similarity measure used	Inner circle mapping	Outer circle mapping	Inner circle mapping	Outer circle mapping
Euclidean	66.17%	75.77%	77.83%	81.26%
Bray–Curtis	64.23%	77.71%	74.51%	80.34%
Squared Chord	58.86%	74.06%	73.37%	76.34%
Chi-Square	59.89%	75.43%	73.60%	77.49%
Extended Canberra	61.14%	74.74%	70.40%	76.34%

Figure 5. Recognition rate (%) versus moment order for binary images on GC-s dataset, using inner circle mapping approach.

Figure 6. Recognition rate (%) versus moment order for grayscale images on GC-s dataset, using inner circle mapping approach.

Figure 7. Recognition rate (%) versus moment order for binary images on GC-s dataset, using outer circle mapping approach.

Figure 8. Recognition rate (%) versus moment order for grayscale images on GC-s dataset, using outer circle mapping approach.

Figure 9. Performance comparison of inner circle mapping versus outer circle mapping approach for binary images on GC-s dataset.

Figure 10. Performance comparison of inner circle versus outer circle mapping approach for grayscale images on GC-s dataset.

Table 2. Recognition rates (%) obtained at different image sizes using both inner circle and outer circle mapping schemes.

Image size		28 × 28	32 × 32	36 × 36	48 × 48	64 × 64
Binary images	Inner circle	60.11%	61.46%	62.03%	63.09%	62.83%
	Outer circle	71.60%	71.03%	72.11%	72.31%	72.57%
Grayscale images	Inner circle	70.54%	71.86%	70.46%	69.66%	66.86%
	Outer circle	75.97%	76.29%	76.46%	75.66%	73.89%

Table 3. Comparison of recognition rates (%) obtained by Euclidean distance and SVM for binary and grayscale images, using both mapping techniques.

	Binary images		Grayscale images
Similarity measure used	Inner circle mapping	Outer circle mapping	Inner circle mapping	Outer circle mapping
Euclidean	61.46%	71.03%	71.86%	76.29%
SVM	67.17%	78.46%	78.03%	81.97%