For the purpose of comparison, we investigated the proposed method with the well-known GMM in three challenging situations: pixel variation, illumination changes and a shadow effect.
Very impressively, even when query sample of one modality is extremely degraded by random pixel corruption, illumination variation, etc., ABSRC can still get performance comparable to the unimodal recognition based on the other modality.
In these experiments, the EMCCD camera was set to a 64 × 64 pixel frame (illumination sequence shown in Figure 3A).
A diffraction grating interferometer-based optical readout is realized by pixel-level illumination of the MEMS chip through the via holes and by capturing the reflected light using a photodetector array on the CMOS chip.
These pixels receive light signals from a number of sources, such as the data-carrying transmitted pixels, the unused transmitter pixels and the illumination outside the transmitter.
Also, the sequence is of low-resolution of size pixels, with decent illumination, and has multiple faces but noncrowded area.
Currently, Apple is using Sony Exmor RS image sensors, but has emphasized improvements like backside illumination and pixel pitch over raw megapixel count.
In another approach, Kalka et al.[8] present quality assessment of iris images based on the evaluation of eight quality parameters (defocus, motion blur, off-angle, occlusion, specular reflectance, illumination, and pixel count).
Cell/substratum distance d at each pixel was derived from illumination intensity I with the low incidence approximation 26, 40: 2where λ is the light wavelength in aqueous medium, and I m and I M are, respectively, the minimum and maximum intensities corresponding to d = 0 and d = λ/4 ≈ 100 nm, respectively.
To decrease the intensity values of the high-illumination pixels and increase the intensity values of the low-illumination pixels simultaneously, the intensity image is treated with enhancement and compression processes, respectively, using a specifically designed nonlinear sine intensity mapping function defined in [6] as T I in x, y = sin 2 π 2 I in x, y q, I in x, y ∈ 0, 1 (3).
Most strategies to solve it are based on determining the particular form of the color transformation which the pixels undergo when an illumination change occurs.
