Latent Filter Image LFI
LFI — Latent Filter Image
An image which is applied by the slit raster technology. The scene of the image changes when changing the angle of observation. A latent filter image consists of a slit raster printed inside a transparent polycarbonate which serves as an optical filter and a scrambled image stripped from two initial images (fig. 1). Lightness of the image changes regarding to the background when changing the angle of observation. Latent (second) image is visualized at an acute angle of observation and printed by offset (fig. 2).
Fig. 1. Scheme of a latent filter image visualization:
1 — scrambled interlaced image stripped from initial images A and B;2 — slit raster; 3 — initial images are visualized at different angles of observation
a
b
c
d
Fig. 2. Estonia. National identity card:
а — reverse side; b — latent filter image: «EST» abbreviation. View at a right angle; c — the same image. View at an acute angle of observation; d — the same image. Slit raster. View at a right angle of observation