|
Translucent fabrics transmit light but provide sufficient diffusion to eliminate perception of distinct images. Traditional
translucent woven fabrics include organdie, silk chiffon and muslin cotton, among many others. When such materials are
used in curtains they provide even light transmission, solar protection and natural lighting, with a wide range of degrees
of view-through. Since all these properties can be referred to the concepts of privacy, space and boundary, they are
highly appreciated in interior design and architecture. The conventional metrics used to characterize a translucent fabric
are the UV or Visible light transmission, the cover factor and the shading coefficient. In this work we propose to use
other metrics commonly utilized to characterize imaging systems such as the Modulation Transfer Function (MTF).
When looking through a curtain, the translucent fabric can be modeled as a low-pass filter that is combined with human
eye imaging system. We replace our visual system by a high-quality still photographic camera. The MTF curve allows
one to characterize the view-through performance of the translucent fabric in a more realistic way than the simple light
transmittance, cover factor or shading coefficient. Two object tests, placed at a distance from the fabric, have been used
to experimentally derive the MTF of the whole imaging system (translucent fabric and camera): a USAF test and a
Slanted Edge (ES) test. In the latter case the Line Spread Function (LSF) is firstly obtained and the MTF estimated. The
method has been applied to a set of translucent fabrics with different thread diameters and densities. From the MTF
curves obtained using both tests, the transparency of the fabrics is objectively and quantitatively characterized in terms of
view-through. The results are presented and discussed.
|
