How to Use Hard Mix Layer Blending Mode in Photoshop
If you process your photos in Adobe Photoshop, most likely you have used layer blending mode like Soft Light, Overlay or Multiply. However, few people knows how to properly use Hard Mix blending mode. Here I will show you a good way to use it.
The photo below was shot in a cold autumn morning in the southern swamp a month ago, fogs/mist were rising from the water surface. Overall, the image is a bit too cool/blueish to my taste, I would like to warm up the fogs and the colorful foliage, but keep the shadows(dark trunks) cool. The resulting warm highlight vs.cool shadow color contrast will certainly enhance the visual appeal of this image. I will use the Hard Mix layer blending mode to achieve the result.
Open the image in photoshop. At the bottom of layers panel, click the adjustment layers icon to open the dropdown menu, select the first item, which is "Solid Color Fill" adjustment layer (follow red arrow).
Double click the Color Fill adjustment layer icon (follow red arrow), to open the "Color Picker" window, select a warm bright color like light orange or similar. Click "OK".
With "Color Fill" layer selected, click the "layer blending mode" dropdown menu (follow red arrow), scroll down until you find "Hard Mix" , and click it.
The image will immediately turn into a horrible mess of blotch, super contrasty saturated colors. This is why very few people use this blending mode by default, the result is always an unsightly mess. But wait, it's not finished yet...
The secret to successfully use "Hard Mix" blending mode is: After you selected Hard Mix layer mode, adjust the "Fill" from 100% to somewhere like "10%-30%" based on your taste. In most other layer blending modes like Soft Light, we adjust "Opacity" to apply the effect, but with Hard Mix, we have to adjust "Fill", NOT "Opacity" to apply the effect to the image on the layer below. In my image here, I change "Fill" to 21%, it warms up the whole image to my liking.
However, I don't like the warmth applied to the shadows like dark tree trunks, which should be staying cool. To remove the warmth effect from the shadow, I will make adjustment of "Layer Style" of Color Fill layer, by double click the empty part of "Color Fill" layer (follow red arrow), "Layer Style" window will open.
In "Blend If" section of Layer Style window, locate the "Underlying Layer" Bar at bottom, move the the little triangular slider from the left, towards the middle (follow red arrow), which means, the hard mix warmth effect we just applied to the whole image, will be excluded from the shadow(dark parts) of the image, so the shadow will be staying cool without any warming applied.
If the transition from the warmth to coolness 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 transition from warmth to coolness in this image. I understand it's hard to understand if you are new to this technique, but if you keep learning and practicing, you will get it.
Here is the final image after the edit, Warmth/Vibrance added to fogs and foliage, while shadows staying cool.