In this test and this one, I showed that you could get the colors of developed files from the Sony a7RIV, the Nikon Z7, and the Fujifilm GFX 100 reasonably close if you used Lumariver Profile Designer, and the reproduction style. The a7RIV and the Z7 were remarkably statistically accurate and even closer to each other than they were to a perfect result.
Lumariver — quite wisely, I think — separates the calibration of the camera (which gets you to the reproduction styles) and the specification of the “look” of any output-referred image coming from the application of the profile. A logical question is, how well does this work in practice?
To find out, I took the same set of test images made using the CC24 target, and the same set of training images using the CCSG target, and the same flat field images from the above-linked tests. I made new profiles using the Lumariver Default style, which is among other differences from the reproduction style, is more chromatic and has a nonlinear tone curve.
The results were surprising to me.
Here are is the overall mean Delta-E 2000 errors, compared to the previous tests:
The Lumariver Default bars are on the right. Notice that, although the Z7 was basically tied for most accurate in the two reproduction profiles, it’s the worst in the Default profile set.
If you look at the rms Delta-E 2000 errors, which penalize outliers more, it’s the same thing:
And if we look at mean chroma errors, we can see that there are more chroma differences with the Lumarive default profile than with the two reproduction profiles:
Now let’s look at the chromaticity differences in pairwise comparisons between the three cameras.
I can’t find any rhyme or reason to these plots. For some of the patches the images from two cameras show nearly the same chromaticity, albeit different chromaticity from the correct one (indicated by the circles). In some cases the pairs of cameras show quite different renderings of the same patch.
Here are the statistics for the errors with respect to the reference:
For those of you who don’t remember them, I’ll include row descriptions the the end of this post.
Here’s how the cameras do when compared only to each other, not to the reference.
This is passing strange. Look at the mean Delta-E 2000 line. The closest camera pair with the reproduction profile was the a7RIV/Z7. With the Lumariver Default profile, they are virtually tied for worst, and the GFX100/a7RIV pair, which was tied for worst with the reproduction profile, is a clear first here.
I think it’s safe to say that, at least in this case, the promise of separating the desired look from the color filter array characteristics of the camera has not been realized.
Here’s an explanation for the rows.
Mean Delta E is the average CIELab delta E. Since Delta E can never be negative, errors in one direction don’t cancel out errors in another.
Mean Delta L is the average difference in the CIELab and CIELuv vertical (luminance) channel. Positive Delta L means that the output is brighter than it should be. Negative Delta L means that the output is darker than it should be. Thus Delta L is good for detecting systematic luminance bias.
Mean Gray Delta L is the average difference in the CIELab and CIELuv vertical (luminance) channel for the 6 gray patches. Positive Gray Delta L means that the output is brighter than it should be. Negative Gray Delta L means that the output is darker than it should be. Thus Gray Delta L is good for detecting systematic luminance bias in the gray axis.
Mean Delta A and B are the average differences in the CIELab and CIELuv a and b channels. Positive Delta A or B means that the output is redder or yellower than it should be. Negative Delta A or B means that the output is bluer or more cyan than it should be. These measures are good for detecting systematic color balance bias.
Mean Delta Cab is the average chroma error measured in Lab. A positive number means that the output colors are more saturated than they should be. A negative number means that the output colors are less saturated than they should be.
Mean Non-Gray Delta Cab is the average chroma error measured in Lab for the 18 chromatic patches. Mean Non-Gray Delta Cuv is the average chroma error measured in CIELuv for the 18 chromatic patches. A positive number means that the output colors are more saturated than they should be. A negative number means that the output colors are less saturated than they should be. The sigma metrics track the standard deviation of the 18 samples.
Mean Delta Hab is the average hue angle error measured in Lab, expressed in degrees. The gray patches are excluded from this measure, since their target hue angle is undefined. A positive number means that the output colors have a hue angle higher than they should have. A negative number means that the output colors have a hue angle lower than they should have. Mean Delta Huv is the same measure in CIELuv. The sigma metrics track the standard deviation of the 18 samples.