Darken Mode

Darken compares the active layer to the underlying image and allows only those areas that are darker than that image to show up (Figures 13.10 to 13.12). It's that simple when you're working on grayscale images, but if you try the same mode out on a color image, you might be surprised by the result.

Color images are usually made up of three components: red, green, and blue. Darken mode compares two layers by looking at red, green, and blue individually. So, let's say you have a layer with some red in it that's made out of 230 Red, 50 Green, and 30 Blue, and you have a layer above it that contains a blue color made from 50 Red, 55 Green, and 200 Blue. The blue in the top layer would usually completely cover up the color below (Figure 13.13), but when you set the top layer to Darken mode, Photoshop will compare the red, green, and blue components of each layer and use the darkest of each. In this case, it would see that the red information on the top layer is darker (50 versus 230; lower numbers mean less light). When comparing the green components, it would see that the bottom layer is darker, and it would see that the blue component is darkest on the bottom layer. So, once it picked the darkest of each, it would end up with 50 Red, 50 Green, and 30 Blue, which would result in a dark yellow color (Figure 13.14). I don't usually think about the red, green, and blue components of each layer when I'm using Darken mode, but I occasionally blame them when I don't get the result I am looking for.

I mainly use Darken mode when I'm retouching an image, which we'll talk about in the next chapter, but for now, let's see how we might use it with Photoshop's filters. Let's say you've chosen Filter > Pixelate > Pointillize, but you don't like all the white areas that show up (Figure 13.15). If that's the case, you can choose Edit > Fade Pointillize immediately after applying the filter, and then you can tell Photoshop how to apply that filter to the original. If you choose Darken, Photoshop will compare the filtered result with the original and only allow the filter to darken the original, which should in effect get rid of the white areas (unless the original contained white) (Figure 13.16). I often use this technique after applying the Sharpen filter, because the bright halos it produces are often distracting. By using Darken mode, I can limit that filter so that it will create only dark halos.