Is artists' perception more veridical?

Abstract

Figurative artists spend years practicing their skills, analyzing objects, and scenes in order to reproduce them accurately. In their drawings, they must depict distant objects as smaller and shadowed surfaces as darker, just as they are at the level of the retinal image. However, this retinal representation is not what we consciously see. Instead, the visual system corrects for distance, changes in ambient illumination and view-point so that our conscious percept of the world remains stable. Does extensive experience modify an artist's visual system so that he or she can access this retinal, veridical image better than a non-artist? We have conducted three experiments testing artists' perceptual abilities and comparing them to those of non-artists. The subjects first attempted to match the size or the luminance of a test stimulus to a standard that could be presented either on a perspective grid (size) or within a cast shadow. They were explicitly instructed to ignore these surrounding contexts and to judge the stimulus as if it were seen in isolation. Finally, in a third task, the subjects searched for an L-shape that either contacted or did not contact an adjacent circle. When in contact, the L-shape appeared as an occluded square behind a circle. This high-level completion camouflaged the L-shape unless subjects could access the raw image. However, in all these tasks, artists were as much affected by visual context as novices. We concluded that artists have no special abilities to access early, non-corrected visual representations and that better accuracy in artists' drawings cannot be attributed to the effects of expertise on early visual processes.

Mid-space-independent deformable image registration

“…Another approach to mid-space based pairwise registration is through constructing an unbiased atlas from the images (Ashburner and Ridgway, 2013; Hart et al, 2009; Joshi et al, 2004). In atlas construction, the observed images are assumed to be instances generated from a template image (atlas) with some geometric and intensity variation.…”

“…In a different approach to achieve symmetry in pairwise registration, both images are deformed and compared in an abstract reference space chosen to be “in between” the native spaces of the images, known as the mid-space (Ashburner and Ridgway, 2013; Avants and Gee, 2004; Beg and Khan, 2007; Chen and Ye, 2010; Joshi et al, 2004; Lorenzen et al, 2004; Lorenzen et al, 2006; Lorenzi et al, 2013; Noblet et al, 2008, 2012; Škrinjar et al, 2008; Yang et al, 2008; Ye and Chen, 2009). Since both images are treated equally, mid-space registration is invariant with respect to the ordering of the images.…”

“…They typically either restrict the space of possible pair of transformations (resulting in fewer degrees of freedom), or penalize those values of the two transformations that move the mid-space away from the native spaces. The most common such constraints, proposed in the mid-space registration and atlas construction literature, are restrictions on the two transformations to have opposite displacement fields (Aljabar et al, 2008; Bhatia et al, 2004; Bouix et al, 2010; Fonov et al, 2011; Guimond et al, 2000; Miller et al, 1997; Noblet et al, 2012; Studholme and Cardenas, 2004; Yang et al, 2008) or velocity fields (Ashburner and Ridgway, 2013; Grenander and Miller, 1998; Lorenzi et al, 2013). In large deformation models, geodesic averaging of the deformations has also been proposed, which preserves the desired properties of the transformations (Avants and Gee, 2004; Joshi et al, 2004; Lorenzen et al, 2006).…”

“…Unbiased atlas construction techniques can constitute mid-space registration, as the images are deformed to the atlas space (Ashburner and Ridgway, 2013; Hart et al, 2009; Joshi et al, 2004). In an atlas construction approach to image registration, the desired output is the deformation field, but not the auxiliary atlas.…”

“…A better-justified generative model, however, progresses from the atlas to the images and compares the deformed atlas to the images in the native image spaces (Allassonnière et al, 2007; Ma et al, 2008; Sabuncu et al, 2009). Taking advantage of this native-space atlas construction resolves the issue of susceptibility to shrinkage-type problems, leading to a proper implicit-atlas cost function for mid-space registration (Ashburner and Ridgway, 2013). Nevertheless, the registration still remains a function of two transformations taking the images to a mathematically defined mid-space.…”