The Auto Levels feature in Capture One 8.2 now has some new options, allowing you to optimize your images more efficiently and with more control.
Auto Levels now has two different modes: linked RGB channel optimization and individual channel optimization.
The new individual channel mode can, for instance, be very efficient for optimizing landscape images of mountains in the winter and spring time, where the combination of UV, snow, blue sky and distant haze can introduce a color cast.
The left image has been optimized using Auto Level set for linked RGB Channel Mode. The right image has been optimized using Auto Level set for individual Channel Mode. The individual channel mode removes the color cast both in the highlights (the snow) and in the shadows giving a much more pleasing image.
A Level tool for each color channel:
Let’s take a look at the image from the comparison above. In order to show you the optical challenges I will start creating three floating Levels tools. This allows me to see all the individual channels at the same time.
When placing a tool underneath another floating tool, it will automatically stick to the first one. Now with the three individual histograms open at the same time, it is obvious to see that the black offset is not the same for the three channels. Distant haze and the high amount of scatter light hitting the lens cause this.
Individual channel mode:
When the histograms look like this, it makes sense to optimize the Levels for each individual color histogram. This can of course be done manually by dragging the end points but the new Auto Levels mode makes it possible to automate this task. To change the Auto Level mode from the default linked RGB Mode to the individual Red, Green, and Blue Channels mode, go the Preferences under the Exposure tab.
In the Preferences for the Levels tool it is now also possible to set the Auto Level Clipping thresholds. These thresholds determine how far into the histogram the shadow and highlight slider moves when using the Auto button in the tool.
The result of using the Auto button for the Levels tool when in individual channel mode. Notice how each color histogram has been optimized. The Exposure Warning is turned on and shows just a bit of highlight warning for areas reading more than 250. The red circle shows the Auto button for the Levels tool.
The default values are set for clipping only 0.1% of the histograms, which works well for most images. Setting higher values for the thresholds will lead to more clipping but will also result in an image with more contrast.
Comparing the two different channel modes:
Now let’s go back to the comparison image where the Auto Levels feature has been applied using the two different modes. When using RGB channel mode we see that the RGB levels histogram gets clamped leaving the individual color histograms untouched.
In Red, Green, and Blue Channel mode the individual histograms get clamped, which leads to a fully expanded RGB histogram. Again it is easy to see the benefit of using the individual channel mode in this case as it leads to a more clean green color of the trees, removes the blue cast of the distant trees and cleans up the color cast in the snow.
Picking a Shadow or Highlight point works differently depending on the Channel Mode:
When the channel mode is set for the default RGB channel, the Shadow and Highlight picker will set the corresponding sliders as well as any target value in the RGB histogram. This will ensure that the White Balance of the image is maintained, which is extremely important for many images
In Red, Green, and Blue Channel mode the Shadow and Highlight picker as well as target values will work in the individual histograms.
All the best,
The Image Quality Professor
The digital pioneer, Niels V. Knudsen, is Phase One’s Image Quality Professor and founder of the IQP blog. Moreover, he is responsible for breakthrough advancements in image quality both in Phase One’s medium format camera systems and in Capture One Pro.