In this approach, Bilateral weight is computed for
each center pixel based on the input (guide) image:
- i: center pixel index,
j: neighbor pixel index
- Ii: center
pixel input image intensity, Ij: neighbor pixel input
image intensity
The following are details of this approach:
- (i-j) is 3-bit for 5×5: use 3 bits
- (Ii - Ij) is 13-bits: quantize to 8 bits
- Pre-compute Wi, j as 8-bit values including normalization and put in a 2D lookup table
- LUT[i][j]: i is 3-bit pix index, j is 8-bit image intensity diff
- Lookup value is 8-bit
- Total storage: 5 × 256 × 8b = 1280 Bytes
- Can be reduced further based on symmetric nature of range
- For 1/Ki (refer to Section 6.7.6.4.4.4)
The LUT organization is shown in Figure 6-168.
Figure 6-169 shows details of weight LUT logic for this approach.