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Figure 4 | EURASIP Journal on Image and Video Processing

Figure 4

From: GRAB: generalized region assigned to binary

Figure 4

Selection of GRAB operator scale. Scale-space pyramid of GRAB operator. Left shows the pyramid of 7 × 7, 5 × 5 and 3 × 3 GRAB operators. The face images on the right are at multiple scales. Face image at left is originally of size 30 × 26 which is upscaled to 150 × 130. The face image at right is of size 150 × 130. The green dots shown in the images are the stable pixels across multiple scales in the pyramid. The corresponding scales can be found comparing relative change in the number of stable pixels. The histograms on the bottom show the frequency of per-image relative differences in stable pixels when the gallery uses either 5 × 5 GRAB operator (G5) or 3 × 3 operator (G3) being compared with the probe using 3 × 3 (P3). The histograms show that the relative differences at G5, P3 are less than at G3, P3 level. In general, one wants to use minimal-matching GRAB level where at least 10% of the pixels are stable as matching using larger GRAB operators will decrease intersubjective discriminability.

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