Last week we started an Advanced Photoshop SIG (special-interest group) at our local photo club. Based on a survey of our members, I chose Blend Modes as the topic for our first meeting. Here’s a cleaned-up version of the notes I used in preparation.

Here’s an image of 0%/25%/50%/75%/100% that you can use in a layer to see the monochromatic effects of blend modes. (Public domain. Click to enlarge.)

For example, here’s the above image in Overlay mode over another image. Note that in this mode, black darkens the image, white lightens the underlying image and 50% gray causes no change.

Here are some tutorials and tools:

• Julianne Kost on Blend Modes: Julianne walks through each of the blend modes in this series of videos:
  • http://blogs.adobe.com/jkost/2010/11/controlling-pixel-interaction-through-blend-modes.html
  • http://blogs.adobe.com/jkost/2010/11/the-second-group-of-blend-modes.html
  • http://blogs.adobe.com/jkost/2010/11/the-third-group-of-blend-modes.html
  • http://blogs.adobe.com/jkost/2010/11/the-fourth-group-of-blend-modes.html
  • http://blogs.adobe.com/jkost/2010/11/the-fifth-group-of-blend-modes.html
  • http://blogs.adobe.com/jkost/2010/11/the-sixth-group-of-blend-modes.html
• Also check out Robert Thomas’ Photoshop Blend Modes Explained.
• Lee Varis  has a free video on Layer Modes Blending Options.
• Corey Barker has a complete series of lessons on Mastering Blend Modes (Kelby Training, $$).
• Channel Power Tools from Roberto Bigano is a handy Photoshop plugin I use to see and apply any of the RGB/Lab/CMYK channels to layers and masks (20€). Also check out the video tutorials there by Giuliana Abbiati.

(Thanks to Scott Loftesnsess for his recommendations to the above list.)

These are some of the techniques I demonstrated:

• Scrolling Through the Blend Modes: Select the layer you want to change in the Layers palette. Select the Move tool. Use Shift- and Shift+ to scroll through all the blend modes and see their effects.
• Difference Mode: Just as a demonstration of the more obscure and creative blend modes, set your brush to white in Difference mode at 20% opacity and paint directly on your image or a copy. Now change the brush to 100% and see what happens. (Don’t forget to return your brush’s blend mode to Normal, otherwise you’ll wonder why it doesn’t work correctly later on.)
• Dodging: Duplicate the image, set to Screen mode, add a black mask and paint on the mask with 20% opacity white.
• Better Dodging (Levels Adjustment Layer Trick): Duplicating your image in a new layer substantially increases the size of your .psd file, so instead of the above, try dodging this way: Add a Levels adjustment layer set to Screen mode. Paint 20% white on a black mask. Just as easy as above, but your layered files will be smaller.
• Burning: Add a Levels adjustment layer set to Multiply mode, paint on a black mask with 20% white.
• Even Simpler Dodge & Burn: All of the above are just experiments to show various options, but perhaps the best way to dodge and burn is to create a new blank layer set to Overlay mode, but don’t change the levels. (It’s just a dummy adjustment layer.) Paint with 20% white to dodge and 20% black to burn. Your file size will be small and the technique is totally non-destructive and reversible. You can erase your adjustments using the Eraser tool or a brush set to 50% gray color.
• Exposure Control w/Gradient: In a new layer, draw a black-to-white gradient from top to bottom. Set to Overlay mode and adjust the opacity. While this works, you can’t move or change the gradient. So instead…
• Gradient in a Layer Style: Don’t create a new layer. In the image layer, open the Layer Styles dialog (fx icon at the bottom of the Layers palette or just double-click in the blank space to the right of the layer’s title). Select the Gradient Overlay and (!) check the box. Select a black-to-white gradient (click the Reverse checkbox if necessary), set the gradient style to Linear. Play with Scale and Angle. Then switch the blend mode (of the gradient, not the layer) to Overlay and adjust opacity. Note that you can drag the gradient in your image area to reposition it! Now you have a non-destructive, changeable gradient tool.
• Vignette in a Layer Style: Like above, but use a black-to-transparent gradient instead of black-to-white and the Radial gradient style. Experiment with the Overlay vs. Soft Light blend modes and the opacity. Unlike Lightroom you can’t change the squareness/roundness of the vignette, but that’s outweighed in some cases by that fact that you can reposition it.
• Increase Luminosity Contrast: Duplicate the layer, set to Overlay blend mode and adjust the opacity. Works, but it pushes the lights and darks to extremes.
• Better Way to Increase Luminosity Contrast: Duplicate the layer, from the menus select Image->Adjustments->Desaturate. Change the blend mode to Luminosity and adjust the opacity. You can also use a curves adjustment (to this layer only) to increase the contrast of the desaturated image and even use a mask to selectively add contrast in only certain areas of your image.
• Even Better Way to Increase Luminosity Contrast: Use the Channel Power Tools plugin (see above) to preview all ten channels (RGB/Lab/CMYK). Select the channel that shows the most contrast in the desired portion of your image. Create a new layer and use CPT to apply the selected channel to that layer. (Or use Image->Apply Image… from the menu.) Select Image->Auto Contrast if necessary to quickly get a contrasty version, particularly if you selected either the Lab “a” or “b” low-contrast channel. Set the blend mode to Luminosity and adjust the opacity. Again, you can apply a Curves or Brightness/Contrast adjustment and a mask as above.
• High-Pass Sharpening: Duplicate the layer. Select Filter->Other->High Pass… from the menu. Adjust the radius to define edges. Use a curves layer or Image->Auto Contrast or a Brightness/Contrast adjustment layer to increase the contrast, then set the blend mode to Overlay, then adjust the opacity.

I hope you find some of these techniques useful and that they help you understand the power of blend modes in Photoshop. Feel free to leave your feedback here.