Camera Module Image Quality Characterization
NomiCam Camera module image quality characterization provides preliminary image quality tunings as early as possible during the camera module development project. This work will help to identify possible imaging related issues already before product prototyping phase. We can also help to select the most suitable camera by characterizing and comparing different candidates.
Characterization images include:
- Black level
- Flat field
- Camera sensor linearity
- Noise characterization
- Studio images
- Siemens star
- Ghost and Flare
Black images are needed to characterize the camera module pedestal and estimate the amount of defect pixels. This can be done also under different temperatures.
Shading characteristics depends on light source spectrum and therefore flat field images are needed with multiple light sources with different spectrums.
GretagMacbeth color checker images are used to create sRGB color conversion matrix. Result of this test is a set of color matrix values under different illuminants.
The target of this test is to check that pixels will not saturate until at maximum digital value.
Camera sensor linearity
Camera sensor linearity test shows how each color channel behaves from pedestal to saturation. If sensor has any non-linearity points those are seen in this test.
Sweep images are used in the IQ characterization and tuning for noise modeling. The model shows amount of noise at different pixel intensity levels.
Image Engineering lightSTUDIO scene is used for color performance evaluation and visual inspection. Captured raw images are processed with NomiCam’s reference ISP to get understanding what level of image quality can be achieved with the camera module.
Camera module resolution is calculated from Siemens Star images. This test tells how sharp the camera module is spatially in the image plane (center to corners).
Camera module sensitivity is calculated with SNR10 measurement. Test reports the lux value when SNR10 level is reached.
Ghost and Flare
These measurements show if the camera lens has any unwanted reflections or artifacts that can decrease image quality.