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Synthetic aperture radar (SAR) images can be utilised in various fields because they are not affected by the time of day or weather conditions. However, in the process of employing active sensors to obtain a SAR image, speckle noise is generated in the image. Speckle noise degrades the ability of computer vision to observe the Earth. To improve imaging performance, an algorithm for removing speckle noise is necessary. For this purpose, the authors propose a speckle-noise removal algorithm. A speckle reducing anisotropic diffusion filter is employed as a pre-processing filter, in which multiplicative speckle noise can be converted into additive noise using a logarithmic transformation. To remove the additive noise, they use a weighted guided image filter. Experimental results indicate that the proposed method exhibits improved speckle noise suppression and edge preservation results compared with those of existing methods.

This study presents a hash rearrangement scheme to improve coding efficiency of high-efficiency video coding for screen content (HEVC-SCC) by sharing hashes of the inter-search with intra block copy (IBC). Of the various methods introduced during the HEVC-SCC development, the IBC search technique can yield tremendous coding gains, but creates a massive computational burden on the encoder side. The authors propose an effective way to generate the IBC hash table to avoid redundant operations required for hash entry computation. Moreover, the authors propose a hash rearrangement scheme to apply the second hashes used in the inter-search to IBC and the corresponding IBC search method to reduce the computational burden and to improve the coding efficiency. The experimental results show that compared with the HEVC-SCC test model (SCM)-8.0, the proposed algorithm results 80% time reduction when considering IBC hash generation itself, and can save 9-30% of hash generation time even taking into account the proposed second hash generation. It can also reduce the hash-based IBC search time by 14.61%. Furthermore, the proposed algorithm can achieve Bjontegaard delta bit rate savings of -0.66, -0.45 and -0.66% on average for all intra, low-delay, and random access coding structures, respectively.

The deblocking filter of the versatile video-coding (VVC) standard is included in the form of an in-loop filter, as a high efficiency video coding (HEVC) standard. The specifics of the deblocking filter of the VVC remain unchanged from that of the HEVC standard. The presence and type of deblocking filter depend on the quantisation parameters and the conditions of the block boundary. There is a far greater complexity owing to the calculations for boundary condition checks. To verify the enforcement conditions of the weak filter and the filter effectiveness, to propose an efficient judgement condition and to improve the filter are attempted. The scope for improvement of the parameters of the conventional in-loop filter is evaluated and that the compression efficiency of the weak filter part should be improved is proposed.

A transparent thin-film transistor-diode (TFT-diode) circuit through the serial connection of a transparent TFT and a transparent graphene diode comprised of an amorphous indium-gallium-zinc-oxide (a-IGZO) active layer and a graphene electrode are demonstrated. Through transferring the graphene electrode onto the fabricated TFT, the TFT operates in a single direction due to the directional operation of the transparent graphene diode. The resulting transparent TFT-diode device can be applied to transparent a-IGZO and graphene integrated circuits.

A new bilateral frame rate upconversion algorithm using the image texture complexity characteristic is proposed. In the proposed algorithm, as the cost function is adjusted according to the image texture complexity, the accuracy of motion estimation (ME) is improved. In the experimental results, the proposed algorithm outperforms the conventional bilateral ME process by 0.32 dB.

The existing thumbnail extraction method generates a thumbnail by reducing the reconstructed frame after a full decoding process. This method is complex and requires considerable time, particularly for higher resolution video. To alleviate these issues, a fast thumbnail extraction method which utilises an intra-prediction mode for high-efficiency video coding (HEVC) is presented. The proposed method reconstructs only the 4×4 boundary pixels needed for a thumbnail image based on the intra-prediction mode. Experimental results indicate that the proposed method significantly reduces the computational complexity and extraction time for a thumbnail image. The visual quality of thumbnail images obtained with this method does not differ significantly from that of images extracted after a full decoding process.

Most demosaicking solutions focus on improving the accuracy of direction estimation for interpolation, and they achieve a highly precise gradient estimation performance. Direction estimation techniques achieve great improvement in objective image quality; however, in terms of subjective image quality there are remaining demosaicking problems to solve. An adaptive window algorithm to reduce demosaicking artefacts by exploiting the colour similarity of neighbouring pixels is introduced. Experimental results confirm that the proposed method produces the best colour peak signal-to-noise ratio and FSIM performance, and achieves great improvement in subjective image quality.

An enhanced constrained one-bit transform (C1BT)-based fast motion estimation (ME) method is proposed. Binary transform-based ME identifies the proper motion vector by transforming the 8-bit pixels in the original image into a low bit depth of the bit plane, substantially reducing the computational complexity and facilitating hardware implementation by using the number of non-matching points (NNMPs) instead of the sum of absolute difference (SAD). However, a motion block size is N × N , therefore the dynamic range of NNMP (0 ≤ NNMP ≤ N × N ) is decreased to 1/256 compared to that of the SAD with 8-bit images (0 ≤ SAD ≤ 256 × N × N ). The higher the NNMP between the current bit plane and the previous bit plane, the more probable that it will be the block most similar to each other. Therefore, the matching error criterion of NNMP is extended to improve ME performance. Experimental results show that the proposed algorithm improves the performance of ME accuracy by 0.27, 0.38 and 0.67 dB compared to the C1BT-based ME, two-bit transform (2BT)-based ME and 1BT-based ME, respectively.

A new bilateral frame rate up-conversion (FRUC) algorithm based on the bi-directional comparison of the texture complexity in the reference frame is proposed. In the proposed algorithm, the accuracy of the motion estimation (ME) process is determined by the comparison of the prediction size in the reference region of the bi-directional ME process. Base on this comparison, the adaptive refinement process is adjusted. In the experimental results, the proposed algorithm outperforms the conventional bilateral FRUC algorithm by 0.27 dB.

Proposed is an error surface based selective mathematical modelling algorithm for quarter-pixel motion estimation during video encoding. In this method, first the tendency of the error surface is assessed. Using the strength of the edge at the error surface, the error surface region is classified as plain or textured. For plain regions, interpolation-free mathematical modelling is appropriate for the quarter-pixel motion estimation method. For textured regions, half-pixel interpolation is needed for more accurate modelling. Additional half-pixel SAD values are calculated and more accurate modelling is completed to find the best motion vector (MV). Experimental results show that the proposed scheme is faster than conventional modelling algorithms, and the PSNR performance is also better than that of competitive algorithms.

This study introduces a block-based motion estimation algorithm based on projection with adaptive window-size selection. Using one-dimensional (1D) projection, the original 2D block-matching problem is translated to a simpler 1D matching problem which eliminates the majority of potential pixel participation. The authors propose an efficient fast-motion estimation method using an intensity gradient algorithm to reduce the encoding time. The proposed algorithm estimates the texture direction of the block, and then a horizontal or vertical projection is employed for the sum of absolute difference calculation. Experimental results show that the proposed algorithm achieves a greater than 60% time reduction with negligible peak signal to noise ratio (PSNR) loss and BR increments.

Proposed is an interpolation-free quarter-pixel motion estimation method based on a mathematical model for video encoding. In this method, only three shift operators and four compare operators are required in each horizontal and vertical direction to find a quarter-pixel resolution motion vector. Experimental results show that the proposed method reaches almost the same performance as an interpolation-based full-search for quarter-pixel motion estimation with much less computational complexity.

A simple algorithm to reduce the computational complexity of two bit transform (2BT) block motion estimation is presented. The difference between pixel intensity and the mean value is added and compared to a certain threshold value. The proposed algorithm is much faster than the conventional 2BT algorithm, while maintaining visual quality.

A fast partial distortion elimination algorithm based on a Hadamard transform and its probability model is presented. Using the Hadamard transform, we obtain local block complexities, and by computing the cumulative distribution function of the local block complexities, we can accurately predict the total matching error without calculation.

Rate distortion optimisation (RDO), which is the best performing mode decision method for H.264, does not consider dependence between neighbouring blocks, because calculating rate distortion (RD) costs for all possible mode sets requires too many computations. However, in H.264 intra coding, RD performance of the current block is affected by reference pixels in neighbouring blocks. Thus, considering dependence between neighbouring blocks can enhance RD performance in mode decision. Proposed is an adaptive RDO for H.264 intra coding. To consider block dependence with only a few more computations, a mode decision criterion is proposed for 14times4 using the partial boundary sum of the squared differences. Experimental results show that the proposed method improves RD performance compared to RDO.

A signal-dependent wavelet transform based on the lifting scheme is proposed. The transform can be made reversible (i.e. an integer-to-integer transform). The reversible transform, followed by arithmetic coding, is applied to lossless image compression. Simulation results indicate that the proposed method is superior to the S+P method.

An efficient feature extraction in the time-frequency plane is proposed for automatic classification of power disturbances. For that purpose, singular value decomposition and principal component analysis are utilised. Finally, the performance of the proposed approach is tested using a maximum likelihood predictor classifier.