This section covers three commonly used Blending Modes - Multiply, Screen, and Overlay. These three Blending Modes are used frequently by photographers for image processing.
Nikolai has already discussed the Normal Blending Mode, as well as Dissolve, Difference and Exclusion. Therefore, the reader is expected to know, and understand, the basics of creating a duplicate layer with the command CTRL-J ( Apple-J on the MAC) to create a copy of the background layer in the Layers Palette. This is done when using the Multiply or Screen Blending Modes.
Here the image was duplicated with CTRL-J and the switched to LAB. In the Layers Palette, the Blend If command was selected from the drop down menu elicited by the Blending Options button in the upper right of the Layers Palette.
His post said "Ditch the burn tool!"
He said "There is a pretty cool way to get the same effect as the dodge/burn tools in an pseudo adjustment layer:
1. Alt + click (Mac: Option+click) on the new layer button in the layers palette.
2. In the New Layer dialog, change the mode of the new layer to Overlay
3. Make sure that Fill with Overlay-neutral color is checked
4. Click OK You've just added a new layer filled with 50% gray. In overlay mode 50% gray has no effect. So how do you use this new layer???
1. Set your foreground color to black (actually any shade of gray darker than 50% will work)
2. Grab the paintbrush (use a fairly large soft-edged
brush) 3. Set the paintbrush opacity (and/or flow) in the 20-50% range
4. Start painting on your new layer
Any areas on the layer that are darker than 50% gray will darken the underlying image (burning). Guess what happens if your foreground color is white (or a shade of gray lighter than 50%)??? You start to lighten the underlying image (dodging). If you dodge or burn an area and you don't like the result? Set your foreground color to 50% gray and paint over the area. The dodge/burn effect will be wiped away!
Because you're doing the dodge/burn with a layer, you can do all kinds of cool stuff:
Use selections to dodge/burn areas of an image (select the area then fill it with an appropriate shade of gray)
Use paths to dodge/burn areas
Use adjustment layers to control the amount of dodge/burn the layer gives
Run filters on your dodge/burn effect (I'm not quite sure why you would want to, but hey, as with anything in photoshop, at some point someone is going to find an application for it)"
Cletus has us add a new layer over the existing background layer, and fill it with neutral 50% gray. This can be gotten from the Color Picker or just selected as an option when Overlay Blend mode is selected. Then, using a brush with Black or White ink, the base image can be lightened or darkened. This allows you to return and change the edit later, without any destructive effects to the base image.
I just find it easier to just create a duplicate layer with CTRL-J and then use the Brush tool directly on the duplicate image in the Overlay Mode with black or white ink as called for and lighten or darken to taste.
In summary, I have discussed some of the uses of the Multiply, Screen and Overlay Blending Modes for Image editing.
You can discuss or ask questions about this tutorial on Digital Grin.