DCT/DST-based transform coding for intra prediction in image/video coding.

Area of Science:

• Digital video coding
• Image and video compression
• Signal processing

Background:

• Conventional Discrete Cosine Transform (DCT) is widely used in video coding.
• Discrete Sine Transform (DST) has shown promise for specific intra-prediction modes.
• Optimizing transforms for intra-prediction is crucial for efficient video compression.

Purpose of the Study:

• To develop and evaluate a novel DCT/DST based transform scheme for video coding intra-prediction.
• To demonstrate the effectiveness of adaptive DCT/DST selection across various intra-prediction modes.
• To validate the performance improvements in the context of High Efficiency Video Coding (HEVC) standardization.

Main Methods:

• A transform scheme combining DCT and type-7 DST for all intra-prediction modes (vertical, horizontal, oblique).
• Applicability to block-based intra-prediction schemes with separable horizontal and vertical transforms.
• Proof of DST optimality for oblique modes, complementing prior findings for horizontal and vertical modes.

Main Results:

• The DCT/DST scheme was adopted into the HEVC standard in March 2011.
• A simplified DST-only approach for 4x4 intra luma blocks was adopted in July 2012.
• Significant BD-rate improvements were observed compared to conventional DCT-based schemes.

Conclusions:

• The adaptive DCT/DST scheme offers superior performance for intra-prediction without additional signaling.
• The findings contributed to the HEVC standard, demonstrating practical benefits in video compression.
• Further simplifications led to reduced implementation complexity while maintaining efficiency.