Figure S3. Modulation transfer functions of light-field
renderings at different microlens conditions. A modulation transfer
function (MTF) evaluates the fundamental spatial resolution performance
and image sharpness of an imaging system from a black and white line
pattern image. In particular, a MTF50, i.e., the 0.5 contrast value from
the MTF curve, represents the resolving power of the images. The Quick
MTF® software measures the quantitative MTF curves
based on a slanted-edge method from the light-field rendering. a) MTF
curves comparison of light-field renderings through NIR-LFC with
iMLA-AFF (red triangles) and NIR-LFC with only iMLA (brown rhombus). The
MTF50 values at each NIR-ULFCs demonstrate that the NIR-LFC with
iMLA-AFF improves the image sharpness of light-field rendering by 34%
(MTF50iMLA-AFF =16.2 cycle/mm, MTF50iMLA= 12.1 cycle/mm). b) MTF curves of light-field renderings depending on
microlens diameter (DMLA) from 25 μm to 100 μm. The
MTF50 value from 30 μm in DMLA is 16.2 cycle/mm, which
is higher than the MTF50 value from 25 μm in DMLA, 15.1
cycle/mm. The smaller DMLA results in more pixels in
each sub-aperture image, which generally improves spatial resolution.
But at DMLA less than 30 μm, the spatial resolution
decreases due to very low magnification. Therefore, the
DMLA of iMLA-AFF is determined to be 30 μm, which
represents the highest MTF50 measurement in the CMOS image sensor of
Sony IMX 219 (pixel size = 1.12 μm).