I. Visually Identifying Image Quality Degradation
1. Sharpness Test
Use a standard test chart (such as the ISO 12233 resolution test chart) to observe the monitor screen. If the horizontal sharpness is lower than the nominal value (e.g., <650 TVL for a 1080P model), performance is degraded.
When shooting still images of text, if edges appear blurry or jagged, it may be a problem with the lens or sensor.
2. Dynamic Image Performance
If you experience stuttering or freezing when shooting fast-moving objects (such as waving a hand), check whether the frame rate meets the standard (≥25 fps is recommended).
II. Professional Testing Indicators
1. MTF Analysis
Test MTF50 (50% contrast) and MTF20 (20% contrast) using Imatest software. If MTF50 is <60% or MTF20 is <40%, resolution is degraded. 2. Color and Grayscale
Shoot an X-Rite 24-color color chart. If the ΔE value is greater than 5 (color deviation) or the grayscale level is less than 8 (SD) or 9 (HD), white balance calibration is required.
3. Low-Light Performance
Test in an environment below 1 Lux. If the signal-to-noise ratio (SNR) is less than 30dB or significant noise is present, the low-light gain algorithm should be checked.
III. Environmental Adaptability Verification
1. Extreme Condition Testing
If color casts or freezes occur in images under high temperature (+70°C) or low temperature (-40°C), this may indicate sensor or circuit degradation.
2. Protective Performance Inspection
If the lens transmittance decreases (e.g., fogging) after prolonged exposure to dust, the explosion-proof cover should be cleaned or replaced.
IV. Maintenance Recommendations
Regular Calibration: Use a standard test chart to test sharpness and color reproduction every 6 months.
Hardware Inspection: Clean the lens seal to prevent oil contamination from affecting the image; replace an aging cooling fan.
