The first area of processing we’re going to look at is color accuracy, and it’s arguably the most obvious results of different processors. The basis of the color processing of any RAW system is how it maps the gamut of colors the camera captures around the axis of the gray (or neutral) point. Generally that mapping is done with considerable detailed information about the characteristics of the camera, often referred to as a “Camera Profile”, although not always a typical ICC profile we see in most color management applications.

Here’s where we’re getting an insight into how the software is guessing we like the file processed. For consumer applications, for example, we often see higher saturation and contrast, since that’s what “looks nice” to an average viewer. Professional applications often will favor a more accurate rendering- more correct, less “pretty”, so the photographer can control the rendering to give the results they intend.

We’re going to look at three cameras- the Canon 5DM2, the Nikon D3X and the Olympus E-P1, just to give a bit of a feel for how these packages deal with different product lines, and to check for consistency in processing trends.

Starting with the Nikon, let’s take a look at the color accuracy between C1Pro, first, and then ACR. The square icons indicate the target values, the circles indicate the actual values rendered by the camera/processor combination.

Click on the thumbnails below to view a larger version of the image.
 

Nikon RAW Files

Nikon D3x: C1 Pro	Nikon D3x: ACR

One of the first things we notice is the general accuracy of ACR in rendering the colors, but the consistent mapping the blue hues in both processors to magenta. ACR, in this case handles the entire gamut slightly better, especially in the typically problematic reds and magentas, but still has the greatest error in the cyan and blues.

Canon RAW Files

Canon 5D Mk II: C1 Pro	Canon 5D Mk II: ACR

Here, we’re seeing a more general accuracy for ACR, but we’re getting an interesting drift in the blues that we’re not seeing in the C1P processing. Of the two, C1P is less accurate overall, with a consistent drift for most colors. However, where ACR goes wrong, it goes very wrong, picking up a significant amount more drift than C1P.

Olympus RAW Files

Olympus PEN E-P1: C1 Pro	Olympus PEN E-P1: ACR

Finally, with the Olympus E-P1 we’re seeing a couple of things. Primarily we’re seeing the results of a sensor that is struggling to capture a full gamut with a smaller sensor and reduced pixels. We’re also seeing the result of a less mainstream camera with significantly less professional market share, and choices that have to be made in committing resources to developing processors for these types of cameras. The result is a file that is a more generic stab at color rendering.

ACR tends to be mapping colors with more error, and to the center- that is, more towards neutral gray. As such, though, the colors are more on-axis- that is,they are closer to the correct hue if they were to be tracked out towards the correct saturation. This could be considered a “safe bet” calculation by Adobe- if you make a small mistake in a generic rendering, it doesn’t get amplified to badly. Phase, on the other hand, maps the colors closer to their correct saturation, but does have some drifting of colors, pretty much in the entire range, and, curiously, shifting consistently to counter-clockwise on our chart.