Abstract
The transparency of thin fabrics has been studied as the property for transferring light from the view point of the visual acuity determined by Randolt's ring-figures through thin fabrics. A definition of opacity of a thin fabric has been given. The results obtained were as follows:
1) First, an influence of conditions of visual inspection were investigated on the visual acuity. Visual acuity=0.4log10 (luminance of back ground, cd/m2) +1.06log10 (contrast) +1.07 where,
contrast= (luminance of back ground) - (luminance of Randolt's ring-figure) / (luminance of back ground)
2) Second, the above result was applied to thin fabrics. The opacity of a thin fabric was defined as follows:
Opacity= (visual acuity) - (visual acuity to Randolt's ring-figure on a white back ground through a thin fabric)
0.66log10 {β/β2+t2} =1.06log10 (t2)
where, β: radiance factor of the fabric,
β2: radiance factor of the back ground of Randolt's ring-figure,
t: transparency of the fabric.
3) The above formula agreed well with the actual visual inspection.
