advanced photoshop

How to use the Divide and Subtract blending modes in Photoshop CS5

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Tips & Tutorials, by The Advanced Photoshop Team

Learn how to use the Subtract and Divide blending modes found in Photoshop CS5

Photoshop CS5 introduced lots of cool new features, but there have been a few quieter additions that haven’t called for drum rolls or fanfares, yet nevertheless present the Photoshop user with a host of new creative possibilities. Such small tweaks to Photoshop are easily overlooked so, over the next couple of pages, we’re going to look at two of these more subtle newcomers which can be found in the layer blending modes in CS5 – namely Divide and Subtract.

Under the hood of Photoshop, blending modes use some quite complicated algorithms and mathematics to blend two layers in a myriad of different ways, but rather than concentrate on algorithms and channel calculations, here we’re going to explore the practical, creative options that these new blending modes present us with.

The key to using blending modes in your day-to-day Photoshop projects is to experiment and be creative, and that’s exactly what we’re going to do here. We’ll show you how to use these new blending modes to create strikingly different and powerful graphic effects, with a workflow that will also present lots of visual alternatives along the way. By using a combination of the image-editing strategies detailed here, and experimenting even more as you go along, you’ll happen upon many unique effects. So, let’s Divide and Subtract!

01 White-out!

How to use the Divide and Subtract blending modes in Photoshop CS5
Open the start image and duplicate the original background layer (Cmd/Ctrl+J). Change the blending mode for the duplicate layer to Divide. You’ll notice at this stage that the entire image turns completely white. To reveal the sketch-like image, we need to blur this layer, so go to Filter>Blur>Gaussian Blur.

02 Blur and reveal

Step 2
The more you increase the Blur Radius (making sure you have Preview checked), the more of the image you’ll reveal. At very high radius values, you’ll create an effective high-key image, which in itself can be a nice single-pass effect using the Divide blending mode.

03 Fine detail

Step 3
In this instance, we want to create a fairly sparse, sketch-like effect, so choose a small Radius value of around 12 pixels and click OK. To remove the colour from the sketch effect, add a Hue/Saturation adjustment layer and reduce the Saturation to -100.

04 Invert for tone

Step 4
The sketch outline effect currently in place is nice in its own right if you’re looking for an arty pencil style, but for our purposes it would be better with a little tone added. To do this, click back on the background copy layer and duplicate it (Cmd/Ctrl+J). Now just click the lower background copy layer and set its blending mode to Subtract. Invert this image layer via Image> Adjustments>Invert.

05 Adjusting the tones

Step 5
To control the tonality of this tone fill layer, go to Image>Adjustments>Hue/Saturation. Essentially, at this stage, the Saturation slider adjusts the lightness of the midtones. The further you drag the Saturation slider to the right, the lighter the midtones will become, and vice versa. Obviously, we want to lighten the midtones here, so quite a high value needs to be applied.

06 The ideal mix

Step 6
The Lightness slider now governs the overall lightness of the image, and the contrast between shadows, midtones and highlights. By juggling these two sliders you can fine-tune the tonal qualities of the image, settling on a value that gives lots of nice, graphic separation between tones. Having made the adjustments, reduce the opacity a little to control the strength of the effect.

07 Gradient for colour

Step 7
There are virtually limitless possibilities for adding colour to the image. Go to Layer>New Fill Layer>Gradient. Click OK to the New Layer dialog and choose any gradient from the Gradient Picker. Set the blending mode for this to Divide. Now double-click the Gradient layer thumbnail in the Layers palette.

08 Playing with colour

How to use the Divide and Subtract blending modes in Photoshop CS5
Now’s the time to experiment. You’ll get a radically different colour toning effect simply by choosing any one of the various available gradients. Even more colour possibilities are presented by adjusting the colour stops located below the gradient. Again, the intensity of the colour overlay effect can be adjusted via the Opacity slider.

09 Solid colour

Step 9
If that’s not enough colour, you can always use a Color Fill layer to add more. Go to Layer>New Fill Layer>Solid Color. For the moment, choose any colour from the colour picker and click OK. Now set the blending mode to Subtract and reduce Opacity to around 50%.

10 Colour to taste

Step 10
Double-click the thumbnail for the Color Fill layer and experiment by picking different colours from the colour picker. You’ll find – because of the blending mode we’re using – that the colours don’t react as you might expect them to, so trial and error is the key here!

11 A little masking?

Step 11
The Color Fill layer comes complete with a layer mask, so you always have the option to paint with black on to this layer mask to hide some of the colour, such as over the background areas behind the model. You could even make selections with the Magic Wand tool on the original background layer and fill the selections with Black on the mask.
Before and After

  • Val Lopez

    Got fantastic results! Thanks for the tips!

  • Dave

    I recently used the Divide blend mode for the first time to achieve a look I really like in Photoshop, but I can’t output it. Saving it as a PSD file results in a completely different look. Even doing a Stamp Visible messes it up. Seems like there’s something funky about this one in CS5.