In my previous post on the subject of the color responses of Aperture, Lightroom and Capture, I mentioned that once I adjusted for exposure and contrast, the rendition that Capture One gave became very bright. The image that I was using was taken with a Nikon D80, and is not particularly badly exposed. Below is the rendering that Aperture gives completely unadjusted:

Aperture 2 test chart, unadjusted

And now the image that Aperture 2 gives when the adjusted. The process that I followed was to adjust the exposure and contrast setting of each program to get the “White” and “Black” patches to exactly the correct values. In both Lightroom and Aperture, this gives a normal looking image - ceratinly more exposed than the original, to be expected given the underexposed "grey" look to the white patch, but generally correct.

Aperture 2 test chart, adjusted for contrast and exposure

The Capture One test chart however is very different; as we might have expected from the numeric results in my previous post, it’s very bright, to the point that the image is becoming washed out. For example, the “Light Skin” patch is effectively no longer skin colored – it’s closer to white.

Capture One V4 test chart, adjusted for contrast and exposure

A numeric view confirms the different brightness behavior of the three programs. The three charts below compare the expected versus actual values for the five neutral toned patches on the D80 test image above. Both Aperture and Lightroom hold the deviation from expected to within 6 units. However, Capture One deviates from its unadjusted tone curve by 21 units, a very substantial difference. Some difference in tone curve is probably unavoidable in practice – at the end of the day, any adjust made to exposure effectively impacts on the tone curve of the raw developer in question. But its clear that Capture One’s exposure and contrast controls interact with the tone curve to an extent not seen in the other software.

A few questions come up here; firstly, is there a better way to make exposure adjustments, and secondly, is this a problem, or just a quirk? The answer to the first question is that while Capture One experts may be able to point out a way to make basic exposure adjustments that doesn’t interact with the Capture one tone curve, when I used the shadow and highlight controls, the only obvious alternatives:

1. I was unable to get both the white and black patch to simultaneously be at the correct value, and
2. Using those controls to adjust basic exposure would rather beg the question of what the role of the exposure and contrast controls should be.

To answer the second question, I attempted to use each program’s brightness control to get the “standard” tone curve for each program after making the adjustments to exposure and contrast. In the case of Aperture and Lightroom, this was quite easy, and I could “dial in” the value of each of the neutral patches to within a unit or two quite easily, using a combination of exposure, contrast and brightness adjustments. For Capture One however, it proved impossible to get close to having all the neutral patches at near to their correct values. The settings required were such that the exposure, contrast and brightness controls ended up at the extremes of their ranges. Given that what I was doing was making fairly minor (less than 1 stop) exposure adjustments, this seems to me to be a fundamental flaw in the way that Phase One have implemented their exposure controls. Now it may be that the forthcoming pro version of Capture One will function differently, but it seems unlikely that so basic a part of a raw developer would change between the standard and pro version.