Authorial subjective evaluation of non-photorealistic images

I argue in favor of a systematic subjective evaluation of non-photorealistic images. Objective measurements are hard to design, and quantitative user studies are problematic for a multiplicity of reasons. Subjective evaluations are not quantitative but are faster to conduct and offer the chance to dig into subtleties that are obscured by numerical scores. By carefully laying out the important elements of the intended image style, and then evaluating their results according to their adherence to the style, researchers can produce convincing evaluations with a manageable level of effort.