Advanced Imaging Tutorials 1

In this series I will randomly post some useful, but somewhat difficult at first, image processing steps that I think are a great addition to a workflow toolkit. I'll be focusing mostly on Photoshop, but Lightroom will have some moves as well.

What did I do to the second image to make it so different from the first?



Lets see a tighter crop of the images.



What's going on here? In the second image, the contrast between the colder plants seems greater with respect to the greener/yellower plants. The sky is also brighter and there are other contrast differences like the bark on the bigger trees as well. This change was brought about by luminance channel blending. What I did was blend about 90% of the luminance information from the blue channel into the green channel. Typically, the green or red channel is blended into the blue channel as the blue channel is normally the weak channel, but in this case, the idea was to make the colder or or bluer plants stand out more against the green plants. I'm not saying I like it any better, but it is an interesting effect that manages to shift around the value relationships without affecting the color palette.

This effect was achieved by using Apply Image in Photoshop, but I could of also used the Channel Mixer. I'll skip describing Apply Image for now and explain how it would be done in the Channel Mixer. The simplest way is to add a Channel Mixer Adjustment Layer with the Blend Mode set to Luminosity and then with the green channel selected in the Channel Mixer, change the green from 100% to 10% and the blue from 0% to 90%. Now, the blue channel's luminosity information is taking over the green channel. Note how the two active channel percentages add to 100%. It's very important to understand that we are not changing any colors, just values and we accomplish that by changing the blend mode of the Adjustment Layer from Normal to Luminosity. See, that wasn't so bad. There's so much more one can accomplish with channel manipulation, so stay tuned to this series for more on this powerful subject.

This image shot just days ago, is from the the Bonny Doon Ecological Reserve highlighted in previous posts. Two horizontal shots were stitched together to form a wider more panoramic view.