In the previous part of this mini-review, I looked at the color response of Capture One, Lightroom and Aperture against a synthetically generated GretagMacbeth test chart. In this post, I’ll look at the response of the same programs against an image of an actual GretagMacbeth test chart. The process that I will follow for the actual image is a little different to that for the synthetic image. In the case of the synthetic image, I made no adjustment whatsoever to the image – the readings are exactly as they appear when the image is imported into each program. For the real image however, I first adjust the contrast and exposure setting on each program to exactly match expected values of the lightest and darkest monochrome patches on the GretagMacbeth chart. This exactly matches the exposure of the real images to the effective exposure of the synthetic image. As was the case for the synthetic images, all the test results are on a 0 to 100 scale, and represent the difference between the expected value as derived from the color values of the GretagMacbeth chart and the actual values measured. So, for example, if the red bar of the “Cyan patch” shows a value of -5, that means that the actual measured value of the R component of the RGB values as read out by the software in question was 5 units less that the theoretical value.

Relative to the synthetic image, Lightroom was, as expected, very close to the theoretical values for the GretagMacbeth chart. Versus a real image however, it shows significant differences, most noticeably in the red patch, where it has significantly more blue and green than might be expected. At first sight, this is a somewhat counter-intuitive result, as while the greater levels of green and blue indicate a more saturated color than the theoretical representation; Lightroom in general has a reputation for excessive red. It’s only in the green patch that there is significant excess red. This would imply that when the complaint of Lightroom’s “excessive red” is made, it is probably more of a complaint about the saturation of reds in the image, rather than an excess of the red color component.




Aperture shows no clear pattern of greater or lesser overall saturation, but does show two interesting characteristics. Firstly, the green components are still very much less than are the case for Lightroom, but at the same time the absolute variation from the theoretical value is far less – versus the synthetic image, the variation was -15.3, but against the actual it is only -6.3. This suggests that the Aperture calibration for the green components in a real image is probably better than Lightroom’s, even though the Lightroom’s better matches the synthetic image . Secondly however there are significant variations in the blue component, especially in the 1.1 profile. The newer 2.0 and DNG profiles show color rendition that is a lot closer to expected values that the previous version. This is consistent with Apple’s statements that the raw conversion subsystem has been substantially revised and improved in the new version. Overall, the actual M8 inages converted with the Aperture 2.0 profile is a better match to theoretical values than either the previous version of Aperture, or Lightroom.





Turning to Capture One, the most significant feature of the charts is the absence of “negative spikes” – while both Lightroom and Aperture have at least some color patches where at least one color is significantly less than the theoretical value, Capture One is relativley better controlled in this respect – only in the yellow patch is there a significant negative deviation. In addition, this control of negative peaks isn’t at the expense of spikes in the positive direct; no spike exceeds 12 units. It’s also interesting to note that in the three primary patches, the red component is within three units of the theoretical value in the red patch, and the green in the green patch and the blue in the blue patch are similarly well controlled. Thus, while Aperture is overall closer to the theoretical values, Capture One is perhaps “closer where it counts”.



In my next post, I’ll take a brief look at color rendering for the same three programs against an actual image from a Nikon D80, so as to get a feeling for whether the patterns here are M8 specific, or relate more to the programs in question.
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