Presentation of Strokes of Extreme Width in Pastel Drawings
|關鍵字:||粉筆;粉蠟筆;寬疏筆觸;非擬真;影像處理;顯像;Non-Photorealistic Rendering;Image Process;Pastel;Stroke;width|
This thesis addresses three problems remaining in two pastel drawing simulating systems developed respectively in 2013 and 2014, during which issues that may incur in the simulation were explored and initial attempts of resolution were made, some of which without much success. The major defect in the previous drawing manifested in the presentation of wide and long strokes, in sparse distribution and lighter shades, over the areas in the scene where color/shade variation being deemed as visually unperceivable. To be specific, the thesis tries to resolve the following 3 issues: (1) Applying wide pastel strokes with visually satisfying width, length and spacing in between over ‘low contrast’ areas in an image; (2) Identifying areas in an image, in a way more consistent with what would have been done in hand drawings, over which the wide pastel strokes in to be applied to; (3) Applying lighter shades of wide pastel strokes visually similar to the effect of wiping the paper very lightly and swiftly with a pastel For (1), measures undertaken in the two piloting systems were discarded and an approach borrowed from a referential survey proved to be satisfactory. For(2), image segmentation in HSV color space used in the piloting systems are incorporated with two complementary segment measures in grey-level space, eliminating difficulties encountered in color space quantization over vast low color-contrast areas in the images (the blue sky, out-of-focus zones, etc.). For (3), instead of decreasing degree of saturation to make a shade(color) look lighter, as done in the old, an alternative without lowing color saturation was exploited with visual satisfaction. In all, the system proposed in the thesis achieves the wide-band pastel drawing effect visually similar to that by a hand-held piece of pastel butt sweeping very gently across the paper with its longitudinal section.
|Appears in Collections:||Thesis|