JVET-AN0237 AHG13: Film grain analysis improvement [M. Radosavljević, F. Lefebvre, P. de Lagrange, Z. Ameur (InterDigital)]

This work presents several enhancements to the film grain analysis process. They include:

• Unified block size (16x16 blocks) used to estimate scaling function and to estimate cut-off frequencies (to speed-up calculations).
• Cut-off frequencies are now estimated by accumulating data over frames.
• Improved cut-off frequencies estimation algorithm.
• The number of different cut-off frequencies (different cut-off pairs) within the frame is limited.

Experiments were carried out on different film grain sequences, and the visual evaluation demonstrated that the estimated film grain parameters result in a higher fidelity representation of the film grain compared to the source.

(note that the sequence of the four changes is different in a version that was uploaded after presentation – the third and fourth bullet points are switched.)

The major change is in the improved cut-off frequency estimation algorithm. Based on a threshold, the cut-off may me switched off in cases where the estimation is likely wrong. In that case, the weight of the highest band is used up to the maximum of the frequency scale.

It was commented by one expert that in case of inputs that had been coded (even if at high rate) it might be necessary to adjust the threshold values. In the reported case however, the processing was done using the grained original and denoised sequences.

Cases were demonstrated where improvements over the previous estimation algorithm (which was already described in the latest draft of ed. 2 of the FG TR) were clearly visible.

Decision: Adopt JVET-AN0237, description to be added in JVET-AN2020, and software in VTM and HM.

Implementation studies (0)

This section is kept as a template for future use.

Profile/tier/level specification (1)

Contributions in this area were discussed during 1250–1310 on Friday 11 Oct. 2025 (chaired by JRO).