Saturday, February 7, 2015

"Autumn at the National Rhododendron Gardens" edit - Part 1: the sky

This post describes step-by-step how I've obtained the final edit of the image in this google+ post of the "Open Source Edit my RAW" discussion group. You can see the final result here.

When editing this picture I had few guiding ideas in mind:

  • the sky was too bright, and I wanted to obtain a more saturated blu tint as well as more contrast and "texture" in the clouds
  • the tree in the foreground is the main element of the composition, so I wanted to give it some "pop"
  • the scene gave me a "late afternoon" feeling, so I wanted to add some overall warm tone

The starting point is the original RAW image, processed using the in-camera settings and the standard Adobe color matrices (for a detailed tutorial on how to open and process a RAW image, see here).

Let's see my editing step-by-step, starting from the sky and clouds. Actually, the techniques described in this and the next posts are not really peculiar to PhotoFlow, and most likely can be applied with minor modifications in other image editors.

Part 1: sky editing

In oder to darken the sky and clouds, I will use a rather common but very powerfull technique, which consists in replacing the luminosity channel of the original image with its own RED channel, and then blend the result back with the original image in "Darken" mode.

The screenshots below shows how this can be achieved in PhotoFlow.

Here are the detailed steps that I've followed:
  1. Add a group layer (I've called it "Sky edit") above the developed RAW image (new groups can be created by clicking on the "G+" button).
  2. Add a "clone" layer inside the group: for that, you have to select the empty row below the group name, than click on the "+" button to open the tool chooser dialog, and then select the "Clone layer" row in the "Misc" tab before clicking the "OK" button to close the dialog.
  3. In the "clone layer" configuration dialog that will pop up, you have to choose the layer corresponding to the initial image (in my vcase "RAW developer") for the layer name, and the "R" channel for the source. The image is graysacle at this point, since we only cloned one channel. To "restore" the colors, set the  blend mode to "Luminosity".
  4. You will notice at this point that the sky got quite darker, but the reddish leaves in the trees became very bright. What we would like is to keep what is darker in this R channel blend, and preserve everything else from the original image... to achieve this, you have to change the blend mode of the "Sky edit" group from "Normal" to "Darken"

There it is! The sky has now a deeper blue and more contrast in the clouds, all that without any masking and unwanted halos around the transition regions. Click on the caption elements to see the original image, the red channel, and the luminosity blend before the final "Darken" blend.

Click type to see: Original - Red channel - R channel Luminosity blend - Final result
The next part will show how the contrast in the foreground tree has been improved through a mid-tones liminosity mask associated to a curves adjustment.

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