A new structure of integer DCT least sensitive to finite word length expression of multipliers

While conventional DCT outputs real numbers and it is not suitable for lossless coding of images, the integer DCT (Int-DCT) outputs integer numbers and can serve as a lossless coding and lossy coding compatible to the conventional DCT. Recently, our group has proposed an optimum assignment method of word length of multipliers in the Int-DCT assuming "colored" spectrum of input signals to reduce total hardware complexity of the circuit. However, it has been ignored to include variations of the integer rotation transforms. This report theoretically and experimentally investigates various rotation transforms and finds the best combination to construct the Int-DCT least sensitive to finite word length expression of multiplier coefficients. As a result, improvement up to 1.8 [dB] to the existing one was confirmed for a colored signal.