I found this while trawling. I hope others get a bit of help from it. Got this from loreleiweb.com The original text was written by Wardo This tutorial is going to give an overview of blending modes in photoshop. Blending modes give you ability to drastically change the way layers interact with each other. Most designers cycle through blending modes using trial and error to determine the correct one to use, but it helps to know a little about what each blending mode does: Normal As you can tell from the name, this is the standard state of the layer and there is no interaction between the current layer and the layer behind it. Dissolve This mode removes a random selection of pixels from the current layer which results in a jagged or fuzzy effect. Darken The darken mode compares the pixels of the current layer and the layer behind it and displays the darker pixels which usually results in a darker image. Multiply This is one of the most useful modes. It works by multiplying the colour of the lower layer with the colour on the top layer, resulting in a darker image. Colour burn This mode darkens the lower layer of the image giving you a dark effect. Linear burn This mode darkens the base layer to create an effect which blends in well with the top layer. This is one of the most complex of the blend modes. Lighten This does the opposite to the darken mode, displaying the lighter pixels. Screen This mode does the same calculations as the multiply but uses the inverse values to display the final image. This mode normally leaves you with a lighter image. Colour dodge This mode lightens the base layer compared to the top layer and leaves you with a lighter image. Linear dodge This is another complex blending mode. It makes the base layer lighter to make it fit in with the current layer more naturally. Overlay This is also a very popular and useful blending mode. It mixes the colours of the base layer and top layer but maintains the highlights of the layers. Soft light This mode determines whether the colours of the base layer are closer to black or white and either lightens or darkens the colours accordingly. Hard light This is very similar to the soft light mode but produces more dramatic results. Vivid light This mode either burns or dodges the colours in the image depending on which colours are present. Linear light Similar to vivid light but uses brightness to alter the colours in the image as opposed to the contrast used by vivid light. Pin light This mode creates varied results and works by replacing colours in an image depending on the lightness or darkness of the colours in the current layer. Difference The colours in the base layer and the current layer are compared and the difference mode subtracts one from the other based on which one is brighter. Exclusion This gives similar results to the difference mode but is usually more subtle. Hue, saturation, colour and luminosity These modes are all quite similar and work by mixing the hue, saturation and brightness from the base layer and the current layer. So there you have it, a basic run down of how blending modes work. I hope you found it interesting and useful.