Krufka, Stephen Edward2020-09-242020-09-242006https://udspace.udel.edu/handle/19716/27741Methods to automatically convert graphics into raised-line images have been recently investigated. In this thesis, concepts from previous research are extended to the vector graphics case, producing tactile pictures in which important features are emphasized. The proposed algorithm extracts object boundaries and employs a classification process, based on a graphic's hierarchical structure, to determine critical outlines. A single parameter is introduced into the classification process, enabling users to tailor graphics to their own preferences. The resulting outlines are printed using a Braille printer to produce tactile output. Critical outlines are embossed with raised dots of highest height while other lines and details are embossed with a lower height. Psychophysical experiments including discrimination, identification, and comprehension are utilized to evaluate and compare the proposed algorithm. Results indicate that the proposed method outperforms other methods in all three considered tasks. The results also show that emphasizing important features significantly increases comprehension of tactile graphics, validating the proposed method's effectiveness in conveying visual information. ☐ Raised-line graphics, while providing valuable boundary information, exclude intensity information contained within images. To address this issue, intensity information is incorporated into raised-line graphics using textures of various roughness. Since no formal definition of roughness exists, we validate through psychophysical experiments that the concept of roughness is universal. A tunable texture is proposed (for Braille printers) based upon a set of guidelines and experimental results found in the literature. We demonstrate that the proposed texture preforms better in identification tasks than relief maps through psychophysical experiments. Hence, the proposed raised-line method coupled with texturing yields tactile graphics with unsurpassed abilities to convey spatial and intensity information.Image processing -- Digital techniquesComputer graphicsBrailleThesis81252974