ILAV   21219
INSTITUTO DE INVESTIGACION EN LUZ, AMBIENTE Y VISION
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Brightness contrast and brightness assimilation in photopic and mesopic adaptations.
Autor/es:
PABLO BARRIONUEVO; ELISA COLOMBO; LUIS ISSOLIO
Lugar:
Kongsberg
Reunión:
Simposio; ICVS 2011. The 21st Symposium of the INTERNATIONAL COLOUR VISION SOCIETY; 2011
Institución organizadora:
INTERNATIONAL COLOUR VISION SOCIETY
Resumen:
The brightness of a region of the visual scene is influenced by the luminances of adjacent regions. This phenomenon is known as brightness induction and includes both brightness contrast and assimilation effects. The different nature of rod and cone pathways could affect this induction. We analyze the effect of light adaptation in the perception of grey patches embedded in three foveal stimuli configurations. A Simultaneous Brightness Contrast display (SBC) , brightness assimilation stimuli were implemented in both a White’s display (W) and a Brightness Illusory Contour configuration (BIC) (Barrionuevo et. al., J. Vis, 9(8), 2009). Using a forced choice method with constant stimuli, we measured the luminance of a grey patch over the black stripe (W and BIC) or over the black square (SBC) that had been matched in brightness to a grey patch over the white region (stripe or square), which had a constant luminance value (Lr). Two adaptation conditions were evaluated, a photopic one (Lr=76cd/m2) and a mesopic one (Lr=0.076 cd/m2). Mesopic condition was achieved using neutral density filters. Three normal subjects were tested. In the SBC configuration, the induction was significantly higher under the photopic condition. However, in W and BIC, the induction was significantly higher under the mesopic condition. In the mesopic range, the low light levels arriving the photoreceptors in the periphery reduce both the lateral inhibition as rod intrution on the test perception, thus the induction in the brightness contrast case is reduced. In the assimilation cases (W and BIC) the opposite found effects show the participation of posretinal mechanisms. These results evidence the different processing of the effects of simultaneous contrast and assimilation in brightness.