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This project was carried out as thesis work during the last semester of my Master studies Electronics Design at the Mid Sweden University. Firstly, it considers a robust and exible implementation of ITU-G4 in hardware based on earlier work, and secondly, it covers review of related work and investigation in the weaknesses of two published designs. More specically, it is an investigation on the robustness of the previously developed VHDL implementation ofthe ITU-G4 algorithm. This includes designing of a debug interface to track the compression process inside the FPGA. The nal result, when comparing to earlier work and other published designs, the ITU-G4 compression performs without any glitches or crashes at certain patterns. The maximum frame rate the design can run at is 60fps at a frame size of 752x480 and clockrate of 33.3MHz. The design is tested with three sets of images: easy, medium and complexwhich are all successfully compressed. This includes imperfect images of bar-codes and Q-codes without the need of morphological preprocessing when comparing to the published design that needs preprocessing for medium and complex images to remove unexpected transitions.

Vacuum harvested peatlands do not easily regain their hydrological function after peat production therefore restoration is required to create hydrological conditions appropriate for the growth of peat producing fen plant species. Peat extraction at Bic-Saint-Fabien peatland by the block-cut method began in 1946, converted to vacuum harvesting in the early 1970’s and ceased in 2000. After exploitation, about 0.04-1 m of residual minerotrophic sedge peat remained; therefore Bic-Saint-Fabien was restored as a fen. Research occurred in 2008-2011 and restoration began fall 2009 so we have two pre-restoration and two post-restoration study years. Rewetting consisted of blocking active drainage ditches, contouring the peat surface into level terraces to even out elevation differences, and building peat ridges (bunds) to retain runoff. Vegetation was introduced to some recontoured parts of the site by the surface layer transfer method. A straw mulch treatment was applied to minimize evapotranspiration. A water budget was created for the harvested cutover area and an adjacent undisturbed section of Bic-Saint- Fabien for all study years. Data collection for the water budget occurred June 2-August 7 (day of year 153-219). Water table, volumetric soil moisture content and soil-water pressure were also examined to better understand the impact of reconfiguration on the hydrology of the system. A 1-1.5 m thick layer of gyttja (a low permeability, high porosity lake-bed sediment) underlies the residual peat; it was parameterized and assessed to see if it could potentially compress and supply water to the overlying peat when the system is stressed. In 2011, the volumetric moisture content and thickness of gyttja were monitored in the field to estimate the strain placed on the gyttja by seasonal water table variability. Gyttja samples were collected and brought back to the laboratory for parameterization and compressibility tests. A water budget was completed annually for the cutover and undisturbed areas of the peatland. There were no distinguishable differences between study years except that 2008 and 2009 were climatologically wetter. During the water budget period surface and groundwater run-on into the cutover area were negligible making precipitation the principle water input. The dominant water loss from the cutover area was evapotranspiration since runoff was only 2 and 9 mm in 2010 and 2011, respectively. Rewetting did not result in a uniform wetness across the cutover site chiefly due to local differences in peat surface elevation. An interior section of Bic- Saint-Fabien remained saturated for nearly all of 2011; it had mean seasonal water table of +2.8 cm, and volumetric soil moisture content and soil-water pressure, 5 cm below the peat surface were 86% and +4 mbar. At a peripheral section (~100 m away) the values were -14.4 cm, 67% and -13 mbar, respectively. While the interior was generally wetter than the peripheral regions, there were some exceptions, notably near where dams were installed on peripheral drainage ditches. The markedly different spatial patterns of wetness suggests that a uniform prescription regarding vegetation re-establishment in the rewetted section may not be warranted. The bulk density, particle density and porosity of gyttja averaged 0.12 g cm-3 1.57g cm-3 and 92%, in the top 40 cm of the layer. The organic matter content of gyttja decreased with depth from about 70% at a 5 cm depth to 45% at a 45 cm depth. Laboratory compression tests showed 9 and 72% strain at effective stresses of 3.5 and 200 kPa, respectively, demonstrating the potential for releasing water upon compression, which in the field is caused by water table lowering. From day of year 192 to 202 in 2011, when a ~8 cm water level change occurred (effective stress range ~0.8 kPa), the volumetric moisture content and thickness of the top 30 cm of gyttja decreased by 0.4%, and 0.5 cm, respectively, representing 0.1 and 1.7% strain, respectively, as determined from these two different approaches. The compression of gyttja after Bic-Saint-Fabien was rewetted (2011) was small but might have been significant under drier conditions with greater water table variability, such as during the early stages of site drainage when it was being prepared for peat extraction or after peat production ceased. The release of water to the peat layer from the compression of gyttja after peat production finished and before rewetting occurred, might have been an important self-preservation mechanism, eventually making it easier to rewet. Water table drawdown in 2011 produced very small strain rates suggesting gyttja compression in this year had no important role; hence rewetting success was more reliant on other rewetting techniques implemented at this site.

Efficient methods for the calculation of radial influence are described and applied to two image processing problems, digital halftoning and mixed content image compression. The methods operate recursively on scanlines of image values, spreading intensity from scanline to scanline in proportions approximating a Cauchy distribution. For error diffusion halftoning, experiments show that this recursive scanline spreading provides an ideal pattern of distribution of error. Error diffusion using masks generated to provide this distribution of error alleviate error diffusion "worm" artifacts. The recursive scanline by scanline application of a spreading filter and a complementary filter can be used to reconstruct an image from its horizontal and vertical pixel difference values. When combined with the use of a downsampled image the reconstruction is robust to incomplete and quantized pixel difference data. Such gradient field integration methods are described in detail proceeding from representation of images by gradient values along contours through to a variety of efficient algorithms. Comparisons show that this form of gradient field integration by convolution provides reduced distortion compared to other high speed gradient integration methods. The reduced distortion can be attributed to success in approximating a radial pattern of influence. An approach to edge-based image compression is proposed using integration of gradient data along edge contours and regularly sampled low resolution image data. This edge-based image compression model is similar to previous sketch based image coding methods but allows a simple and efficient calculation of an edge-based approximation image. A low complexity implementation of this approach to compression is described. The implementation extracts and represents gradient data along edge contours as pixel differences and calculates an approximate image by performing integration of pixel difference data by scanline convolution. The implementation was developed as a prototype for compression of mixed content image data in printing systems. Compression results are reported and strengths and weaknesses of the implementation are identified.