Guest post By Michael Hoffman
The Luminosity Blend Mode allows us to use the brightness values from one layer to make adjustments to the brightness of underlying layers, without creating unwanted shifts in the hue of the underlying layers.
This can come in useful with our sharpening workflow.the image below is an example of an image that was sharpened heavily, and the resulting halo along the edge boundary. This has developed some weird color shifts as a result of the sharpening:
Let’s take a look at three ways to use the principles with Luminosity Mode blending to eliminate the color shifting, and leave the hue intact as we add brightness and darkness along the edges to sharpen our images. You may have seen recommendations that you convert your image from RGB to Lab and sharpen the L channel, then convert back to RGB. This technique will achieve essentially the same result, without the conversion – and without having to flatten a multi-layer image.