Adding radiance/glow to your image with Linear Light layer blending mode
This article is the second one in my layer mode series tutorials, last time I demonstrated Hard Mix blending mode, and today I will show you a practical way to use Linear Light layer blending mode combined with Gaussian Blur to achieve a glowing/radiance effect on the image. The photo below was shot last year during Palouse workshop at sunset time, capturing the beautiful rolling hills bathing in light and shadows. Overall, the image out of camera is too flat comparing to what I saw at the time, I would like to increase the contrast and add atmospheric glow/radiance to the highlight and midtones. I will use the Linear Light layer blending mode and Gaussian Blur to achieve the result.
STEP 1 Open the image in photoshop. click the background layer, press Cmd+J on Mac or Ctrl +J on PC, to duplicate the background layer.
STEP 2 With the duplicated "Layer 1" selected, Click Filter/Blur/Gaussian Blur. The Gaussian Blur window opens, increase the radius to somewhere between 30-60 if your image is the high resolution raw file from the camera (20-60mp sensor).
Next, with "Layer 1" selected, click blending mode dropdown menu, and select "Linear Light", you will see an overly contrasty image(below) because "Linear Light" blending mode dodge the highlights, burn the shadows and increase the contrast of midtones simultaneously. Don't worry, this is not the result I want, more steps to go...
Just like Hard Mix mode I demonstrated last time, Linear Light mode will only be useable, if you lower the value of "Fill" to somewhere between 10% to 30% depends on your taste.
As you can see the image above, the combination of Linear Light blend mode and Gaussian Blur, is making the image glowing/radiant and contrasty, creating a nice atmospheric effect. However, the glow and contrast only look nice with highlight and midtones, the deep shadows(trees and houses at the foreground) look too dark. Also, the brightest highlight on the building is blown out. To solve these problems, I will use "Blend If" in layer style to remove the Linear Light effect and Gaussian blur from the deep shadows and the brightest highlight.
Double clicking Layer 1, the Layer Style window opens (below)
In "Blend If" section of Layer Style owindow, locate the "Underlying Layer" Bar at bottom, move the the two little triangular slider on both sides of the bar, towards the middle (follow red arrow), which means, the Linear Light and Gaussian Blur effect I just applied to the whole image, will be excluded from the dark shadow(very dark parts) and bright highlight (very bright parts) of the image.
If the tonal transition from the contrasty glow effect to no effect is a bit too abrupt, we can split the "Blend If" slider to ease (feather) the transition. Hold down "option" key on Mac or "Alt" key on Windows, click the left part of the slider and drag left(follow red arrow), this will split the triangular slider into two parts, the portion between the two half sliders will have gradual tonal transition in this image, which will makes the image look much natural.
Here is the final image after the edit, contrast and radiance/glow effect were applied to the image except its dark shadows and bright highlights.