Evaluation Of Memory Colors And Subjective Image Quality Across Cultures

Memory color is the typical color of an object that an observer acquires frequently and memorizes stably through his or her experience with the object.The memory color reproduction is an important factor in judging quality of photographic images of real life.The objective of the research project was to investigate long-term memory colors and subjective image quality on preference and naturalness across two cultural groups,i.e.Chinese and German.The first part of this project investigated the long-term memory colors of twenty-six familiar objects among Chinese and German observers.Three experiments were conducted to evaluate the variation introduced by culture effect,context-based grey image and initial matching color.Observers matched memory color patches of familiar objects using three perceptual attributes,i.e.lightness,chroma and hue angle on a well-calibrated display in a complete dark room.Experimental data was analyzed in CIELAB color space quantitatively and qualitatively.The intra-and inter-observer variability were calculated and compared by a measure of MCDM.Confidence chromatic ellipses were fitted as a measure to visualize the spread of values and to quantify the boundary of the group data.The results show that inter-observer variability was twice larger than intra-observer variability.Overall,cultural effect was larger than experimental setting of grey image,but less than inter-observer variability within groups.The hue navigation direction caused much trouble because of the increase of difficulties in color matching.The second part focused on the image quality on preference and naturalness using 1-and 2-dimensional colour attributes across two cultural groups.The goal of this research was to contribute scientific clue relating to the effectiveness of both 1-and 2-dimensional colour appearance attributes and cultural effect for colour image preference and naturalness enhancement.Images were rendered on 7 different color attributes and on 4 different scales.Method of paired comparison was adopted for image preference and categorical judgement for image naturalness assessment.Image results show that the influence of colour attribute variations on image quality can be described by quadratic function regardless of attribute dimensions and image content difference.Thus,this could be a potential effective method for image enhancement.Overall,colour attribute performance on image preference and naturalness varied with image content.There shows a great correlation between natural colors and preferred colors and also shows a great consistency with memory colors.The experimental results show that Chinese observers preferred more colorful colors than German and regarded them as more natural colors.