Saturday, February 14, 2015

"Autumn at the National Rhododendron Gardens" edit - Part 2: more sky editing

In this second part of the step-by-step description of my final edit of the image in this google+ post of the "Open Source Edit my RAW" discussion group, I want to introduce another simple yet powerful technique for enhancing the sky in landscape pictures.

The technique consists in blending the "b" Lab channel with the original image in "Overlay" mode. Below you can see a comparison between the original image, the result of the previous step, the result of the "b" channel blend and the "b" channel itself.

Click type to see: Original - Step 1 result - "b" channel Overlay result - "b" channel

In the "b" channel, anything that contains some blue is below 50% and gets darkened in the overlay blend, while "yellowish" areas (including leaves and grass) are above 50% and result in lighter tones after blending. In order to keep the lightness of the tree and grass close to the original, I've added a slightly darkening tone curve to the Overlay blending input. The tone curve, as well as the settings for the "b" channel blend, can be seen in the screenshot below.

The nice thing with this technique and the one described in the previous post, is that the result is achieved using only the image data itself, without any masking. The effect is therefore very "natural", without any presence of disturbing halos in the transition areas.

In order to simplify the application of this steps, I've prepared a preset that automatically adds a group layer containing both the red channel blend and the "b" channel overlay. The preset can be downloaded from here
The technique turns out to be also quite powerful for haze removal. Below I have applied the preset to the RAW image shared in this google+ post (mouse over to see original image):

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