The UDC’s unique flare characteristics
UDC flares arise from light diffraction as it passes through the display panel above the digital camera lens. Thus, it is essential for each frame in the UDC video dataset to precisely depict the UDC’s unique flare characteristics, including spatially variant flares, light source variant flares, and temporally variant flares. The P-OLED dataset rarely exhibits flares as it captures images displayed on a monitor in a controlled environment.
Visual comparison
| VidUDC33K (GT) |
UDC-VIT (GT) |
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| VidUDC33K (Input) |
UDC-VIT (Input) |
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Spatially variant flares
Since UDC distortion increases outward from the camera lens center, spatially variant flares manifest within an image. Distorted PSFs must be convolved across different image regions to depict this flare distortion accurately. However, VidUDC33K applies the same PSF convolution across all areas using Equation below, failing to represent spatially variant flares.
\[I_t^{D} = f(\gamma \cdot I_{t}^{G} * k_t + n),\]
where $I_t^{D}$ and $I_{t}^{G}$ denote the UDC-degraded and ground-truth frames, respectively. $\gamma$ is the intensity scaling factor, $k_t$ refers to the diffraction kernel (i.e., PSF), $n$ is the noise, and $f$ denotes the clamp function for the pixel value saturation.
Light source variant flares
Various light sources, such as artificial (e.g., fluorescent, LED and halogen) and natural light, can alter the spectra, affecting UDC flares’ shapes. However, VidUDC33K fails to depict light source variant flares.
| VidUDC33K (GT) |
UDC-VIT (GT) |
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| VidUDC33K (Input) |
UDC-VIT (Input) |
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| VidUDC33K (GT) |
UDC-VIT (GT) |
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| VidUDC33K (Input) |
UDC-VIT (Input) |
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Temporally variant flares
A notable characteristic of UDC videos is temporally variant flares caused by the camera’s motion when capturing light sources. The motion results in changes in PSFs. However, in the VidUDC33K dataset, attempts to simulate PSF changes through inter-frame homography matrix computations using the method proposed by the previous studies yield rare temporally variant flares.
| VidUDC33K (GT) |
UDC-VIT (GT) |
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| VidUDC33K (Input) |
UDC-VIT (Input) |
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