Tone-mapped image statistics and quality

This is a supplementary materials of the paper: "Assessment of video tone-mapping: Is camera's S-shaped tone-curve good enough?"

This page contains a detailed analysis of the relation between tone-mapped video quality and either tone-mapping parameters or tone-mapped image statistics. The following plots show the relation between measured image quality (z-scores) and the parameters of tone-mapping. The plots are grouped by attributes, which are either derived from tone mapped video statistics, or estimated from the generic tone mapping operator (ex: Generic TMO: Exposure is the exposure applied by the generic tone mapping operator). For each group, the data is plotted separately for each of the seven plots. The clips in the first row contain the day-time scenes, the clips in the second row are the night-time scenes. The Fountain, Ocean, Flower and Bridge Studios clips were made from HDR panoramas, while the three Rivoli clips are coming from a driving simulator.

During the experiment, 5 variations of the parameters were considered for the 4 operators, resulting in 20 video sequences for each. In the plots, four different colors are used, one for each tone mapping operator. Each variation of tone-mapping and its parameter values is assigned a unique label number, which is the same on each plot. Hovering the mouse over that number reveals operator parameters and clicking on that number (on the right of each plot) opens a page with an example of a tone-mapped frame, a tone-curve and other details.

The value of the correlation coefficient R between the quality and a given attribute is shown above each plot.

Note: if your screen is smaller than 24', you may want to zoom out this web-page for a better visualization.

Attributes from tone mapped video statistics:

Image brightness correlate: Median of tone-mapped image CIE Lab* lightness

Correlation coefficient: 0.66022	1
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Correlation coefficient: -0.018632	1
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Correlation coefficient: 0.53006	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: -0.54156	1
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Correlation coefficient: -0.56742	1
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Correlation coefficient: -0.68029	1
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Correlation coefficient: -0.62731	1
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Image chroma correlate: Mean of tone-mapped image CIE Lab* chroma value

Correlation coefficient: 0.84947	1
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Correlation coefficient: 0.82486	1
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Correlation coefficient: 0.79343	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.064492	1
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Correlation coefficient: 0.3647	1
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Correlation coefficient: 0.44596	1
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Correlation coefficient: 0.43988	1
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Image global contrast correlate: Standard deviation of the CIE Lab* lightness

Correlation coefficient: -0.35359	1
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Correlation coefficient: -0.51992	1
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Correlation coefficient: -0.66464	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.42867	1
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Correlation coefficient: -0.50054	1
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Correlation coefficient: -0.21406	1
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Correlation coefficient: -0.097658	1
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Image sharpness correlate: standard deviation of the CIE Lab* lightness averaged over 8x8 pixel windows

Correlation coefficient: -0.0013809	1
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Correlation coefficient: 0.45644	1
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Correlation coefficient: -0.65994	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.01262	1
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Correlation coefficient: -0.3935	1
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Correlation coefficient: -0.25191	1
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Correlation coefficient: -0.20746	1
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Generic TMO Attributes:

Comparing operators between each other is difficult because each one employs different parameters and processes images in a different way. To allow quantitative comparison of tone-mapping results at a range of parameter settings, we need to bring them to a ``common denominator' that would explain their behaviour in a consistent way. To achieve this, we fit parameter values of a generic tone-mapping operator [Mantiuk and Seidel, 2008], so that it approximates the results of the four investigated video operators.
The generic operator is a sequence of three operations: a parametric tone curve, followed by spatial modulation transfer function (MTF) and color saturation adjustment. The operator was shown to be capable of approximating a wide range of both local and global operators. To get one set of parameters for each video sequence, we fit generic operator parameters for 10 equally spaced frames and average them together. The goodness of fit is validated by computing the PSNR between the original tone-mapped image and that produced by the generic operator. The mean PSNR value was on average 35 for all operators except iCAM06, which was approximated with the mean PSNR of 24. As the result of fitting, we obtain five parameters describing the tone curve, six parameters of the MTF and one color saturation adjustment value. Such statistics let us quickly determine what is relative brightness, contrast and color saturation in the resulting sequences as they are compared to each other.

Generic TMO: Exposure

Correlation coefficient: -0.30818	1
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Correlation coefficient: -0.030681	1
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Correlation coefficient: -0.11823	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.024812	1
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Correlation coefficient: 0.59877	1
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Correlation coefficient: 0.70982	1
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Correlation coefficient: 0.76103	1
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Generic TMO: Contrast

Correlation coefficient: -0.67018	1
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Correlation coefficient: -0.81811	1
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Correlation coefficient: -0.72796	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.18469	1
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Correlation coefficient: 0.55813	1
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Correlation coefficient: 0.62168	1
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Correlation coefficient: 0.59936	1
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Generic TMO: Low Midtone Range

Correlation coefficient: 0.23058	1
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Correlation coefficient: -0.16057	1
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Correlation coefficient: 0.55179	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: -0.41237	1
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Correlation coefficient: -0.10389	1
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Correlation coefficient: 0.048839	1
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Correlation coefficient: -0.1683	1
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Generic TMO: High Midtone Range

Correlation coefficient: -0.15383	1
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Correlation coefficient: -0.22981	1
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Correlation coefficient: -0.051078	1
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PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.24065	1
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Correlation coefficient: -0.20613	1
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Correlation coefficient: -0.21048	1
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Correlation coefficient: -0.21516	1
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	18
	19
	20

Generic TMO: Saturation

Correlation coefficient: 0.54405	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
	16
	17
	18
	19
	20

Correlation coefficient: 0.46563	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
	16
	17
	18
	19
	20

Correlation coefficient: 0.47274	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
	16
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	19
	20

PTMO {g=2.2, c=0.6}

PTMO {g=1.6, c=1.8}

PTMO {g=2.2, c=1.8}

PTMO {g=2.8, c=1.8}

PTMO {g=2.2, c=1}

DATMO {e=1, c=0.6}

DATMO {e=0.6, c=1.8}

DATMO {e=1, c=1.8}

DATMO {e=3, c=1.8}

DATMO {e=1, c=1}

Camera {x=medium, c=0.6}

Camera {x=long, c=1.8}

Camera {x=medium, c=1.8}

Camera {x=short, c=1.8}

Camera {x=medium, c=1}

iCAM06 {p=134, ct=0.5}

iCAM06 {p=134, ct=0.65}

iCAM06 {p=33, ct=0.65}

iCAM06 {p=536, ct=0.65}

iCAM06 {p=134, ct=0.8}

Correlation coefficient: 0.30411	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
	16
	17
	18
	19
	20

Correlation coefficient: 0.73918	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
	16
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	18
	19
	20

Correlation coefficient: 0.65802	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
	14
	15
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	17
	18
	19
	20

Correlation coefficient: 0.52914	1
	2
	3
	4
	5
	6
	7
	8
	9
	10
	11
	12
	13
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	20

Tone-mapped image statistics and quality

Attributes from tone mapped video statistics:

Image brightness correlate: Median of tone-mapped image CIE L*a*b* lightness

Image chroma correlate: Mean of tone-mapped image CIE L*a*b* chroma value

Image global contrast correlate: Standard deviation of the CIE L*a*b* lightness

Image sharpness correlate: standard deviation of the CIE L*a*b* lightness averaged over 8x8 pixel windows

Generic TMO Attributes:

Generic TMO: Exposure

Generic TMO: Contrast

Generic TMO: Low Midtone Range

Generic TMO: High Midtone Range

Generic TMO: Saturation

Image brightness correlate: Median of tone-mapped image CIE Lab* lightness

Image chroma correlate: Mean of tone-mapped image CIE Lab* chroma value

Image global contrast correlate: Standard deviation of the CIE Lab* lightness

Image sharpness correlate: standard deviation of the CIE Lab* lightness averaged over 8x8 pixel windows