Aperture Faux Xprocess Primer

Left: Original | Center: Photoshop | Right: Aperture

Yesterday, I came across a great tutorial called Curvy Cross Processing by Mark Fleming, on using Photoshop’s s-curve to approximate a cross-process look for digital images. Reading my way through Mark’s curves-only tutorial, it became clear that I could probably replicate his approach using Aperture’s levels tool. Since Aperture’s initial release people have been clamoring for a xprocess adjustment block or plugin and I wanted to see if I could get a pretty good xprocess look using levels combined with a little contrast and A2’s new Vignette tool (which rocks!).

Above are two example images. On the left is the original image, in the center the Photoshop image and on the right the Aperture image. The altered images are pretty similar. The photoshop image is slightly punchier. Further along in the primer I’ll get in to the differences.

The Faux Xprocess

I started with the original image in Aperture, adding vignetting to the image (so that each of the final versions would have vignetting). Next, I created a new version for Photoshop and applied the Curves as per the instruction’s of Curvy Cross Processing. I then created another version (from the original) for the Aperture Levels version and played around with Levels until I got the desired effect. It took me a few different tries to get Aperture’s Levels to start looking like the Photoshop version. Below are screenshots of the Curves (Photoshop) and Levels (Aperture) tools:

Left: Photoshop curves | Right: Aperture Levels

In the Aperture Levels version, I turned on the Levels block and dragged the black and white points to the center on the red and green channels, for the blue channel I dragged the quarter tones toward the edges. I’d be fibbing if I said this primer was scientific, basically I just groped around in the dark until I came up with something that seemed to visually equate the Curves version. The best explanation I can come up with is that Aperture’s Level tool combines Curve’s x-axis and y-axis into one plane and so when you move the black, grey or white tones, you’re moving both in and out points. Quarter tones are analogous to the spots in the Curves graph where you’d place points to create the (sometimes magical) S-Curve. You can find more info AUPN article.

The devil is in the details

On first glance, the versions seem to match up pretty well. Some slight differences, but nothing a little tweaking with contrast, saturation, exposure etc… couldn’t fix, but the similarities stop there. As I zoomed into the images, displaying them at 100% I immediately started to notice the banding and posterization in the Levels version. The tonal qualities are not smooth. I also noticed that the Levels version introduces noise into the areas where the posterization breaks up the tones. It’s especially noticeable where the image hits full black. Examples below:

Left: Original | Center: Photoshop | Right: Aperture | details at 100%

I had originally started this post, with the idea of showing how you could accomplish anything with Levels that you could do with Curves, but this just isn’t the case (IMHO). From various experiments like this one, it seems that Curves is a much more elegant solution then Levels. Even when not working on a cross-process look, essentially just trying to recreate a standard s-curve, Levels really chunks up and starts banding and posterizing the image. I think it’s definitely possible to recreate the look of an s-curve simply by using Aperture’s Exposure and Enhance bricks. But strictly using Aperture’s Level brick, I don’t think it’s possible. It’s my suspicion that Levels really only works well when used subtly and judiciously. Unfortunately I couldn’t really figure out how to manipulate the red, green and blue color channels, in Aperture, any other way so for the purpose of this exercise I’m using Levels.

“And so, what are you saying?”

Aperture’s adjustment bricks are sequenced from top to bottom and Apple kinda gives you hints that adjusting photographs should be done in a top down sequence, starting with the Raw Fine Tuning to White Balance* to Exposure to Enhance and then to Levels. From Aperture 1.5 to 2.0, the Levels brick was knocked down a (er, um) level or two and a lot of the adjusting that was done with the Levels brick, can now be done, much more elegantly, with Aperture 2.0’s Exposure and Enhance bricks. The only real reason, I can see, to use the Levels brick is to alter the red, green and blue channels. I could be wrong on this (chime in, if so). It’s my opinion that the Aperture team knows that the Levels brick is kinda busted. I wouldn’t be surprised if it gets a major revamp with the next major version, to address the banding issue and to give Aperture a really strong channel adjustment tool. So, if you’re looking for a cheap and dirty way to do cross processing in Aperture this primer will work fine. For those that want finer tonal qualities, you’ll probably have to wait for a third party plugin or a revamp of the Levels tool, which ever comes first.
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* This is another A2 oddity, they moved the White Balance brick up in the adjustment order. White Balance will change based on Exposure, so wouldn’t the Exposure brick come before the White Balance Brick?