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The noise test can be applied to all gray scales and color charts.
- Select the test chart.
- Select the test (Noise Analysis).
- Open the test image.
- Click Analyse.
The noise test computes also signal-to-noise ratio (SNR), dynamic range (DR),
tonal range (TR), and color sensitivity (CS).
The quantity of noise is not the only factor when analysing the noise.
The quality of noise has remarkable effect on the image quality:
- Chroma noise reduction is usually more difficult than luminance noise reduction.
- Chroma noise is usually more disturbing than luminance noise.
- Low frequency reduction is usually more difficult than high frequency noise reduction.
- Low frequency noise is usually more disturbing than high frequency noise.
Particularly low frequency chroma noise reduction is very difficult and is very disturbing.
Therefore the quality of noise should be analysed very carefully.
Naturally the image processing application of the user has also remarkable effect on the image quality,
because the noise reduction algorithms of the image processing applications differ remarkably from each other.
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The noise test computes the quantity and quality of noise.
The noise test computes the noise levels of red, green, and blue channels in the RGB color space and
L, C, a, and b channels in the LAB color space.
The noise levels in the LAB color space enables separate analysis of luminance and chroma noise.
The noise levels in the RGB color space are expressed in percentages of the maximum intensity.
The noise levels in the LAB color space are expressed in absolute values.
The noise test computes also signal-to-noise ratios (SNR), dynamic ranges (DR), and
tonal ranges (TR) and color sensitivities (CS).
The signal-to-noise ratios are expressed in desibels.
The dynamic ranges are expressed in f-stops (EV).
The tonal ranges and the color sensitivities are expressed in bits.
The noise test draws four or eight plots depending on whether the noise test in frequency domain is disabled or enabled.
The first plot includes the noise levels in the RGB color space:
- The noise of the R component (red)
- The noise of the G component (green)
- The noise of the B component (blue)
- The total noise in the RGB color space (black)
The second plot includes the noise levels in the LAB color space:
- The noise of the L component (red)
- The noise of the a component (orange)
- The noise of the b component (yellow)
- The noise of the C component (gray)
- The total noise in the LAB color space (black)
The third plot includes the signal-to-noise ratios and the dynamic ranges:
- The signal-to-noise ratio (dark blue)
- The dynamic range (light blue)
The fourth plot includes the tonal ranges and the color sensitivities:
- The tonal range (gray)
- The color sensitivity of the R component (red)
- The color sensitivity of the G component (green)
- The color sensitivity of the B component (blue)
- The total color sensitivity (black)
The last four plots include the noise levels in the frequency domain in the RGB and LAB color spaces
if the noise test in the frequency domain is enabled.
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