As we continue our journey through the many ways of converting color photos to black and white in Photoshop, we've so far looked at how to convert a color photo from the RGB color mode to the Grayscale color mode, how to desaturate the color in the image using a Hue/Saturation adjustment layer, and how to replace the original colors in the image with a black-to-white gradient using a Gradient Map.

In this tutorial, we'll look at our fourth way of converting color photos to black and white, this time using the Luminosity layer blend mode, which deals only with the brightness values in the image, ignoring the color information. At the end of the tutorial, we'll see how to improve on the results using a couple of additional blend modes, and how to target specific areas of the photo with a layer mask!

Here once again is the photo I'll be using throughout these tutorials so we have an easy way of comparing the results of our black and white conversions:

Let's get started!

Want an easier way to learn Photoshop? Download our tutorials as Print-Ready PDFs!

Step 1: Add A New Blank Layer Below The Background Layer

The first thing we need to do with our Luminosity technique is to create a new layer. If we look in our Layers palette, we can see that with our photo newly opened in Photoshop, our document contains just one layer named Background. This is the layer our photo is sitting on:

The problem is, we need the new layer to appear below the Background layer. It's a problem for two reasons. First, by default, Photoshop adds new layers above the currently selected layer, not below them, and second, Photoshop doesn't allow us to place anything below the Background layer (since, after all, it's supposed to serve as the background for the document).

Fortunately, there's a simple solution. To get around the problem of not being able to add anything below the Background layer, we just need to rename the layer to something other than "Background". The quickest way to do that is to hold down your Alt (Win) / Option (Mac) key and double-click directly on the word "Background" in the Layers palette. Photoshop will change the name of the layer to "Layer 0":

Then, to add a new layer below "Layer 0", hold down your Ctrl (Win) / Command (Mac) key and click on the New Layer icon at the bottom of the Layers palette:

Holding down the Ctrl / Command key while clicking on the New Layer icon tells Photoshop that we want the new layer to appear below the currently selected layer, and if we look once again in the Layers palette, we see that a new layer named "Layer 1" has appeared below our original layer:

Step 2: Fill The New Layer With White

We're going to be changing the layer blend mode of the image to Luminosity, and the way the Luminosity blend mode works is that it blends the brightness values of the layer with the color of the layer (or layers) below it. At the moment though, the layer we just added below the image is blank, which means the Luminosity blend mode won't work since it will have nothing to blend the brightness values of the image with. Let's fill the new layer with white.

With "Layer 1" selected in the Layers palette (selected layers are highlighted in blue), go up to the Edit menu at the top of the screen and choose the Fill command:

This brings up Photoshop's Fill dialog box, which gives us an easy way to fill the layer with a color. Set the Use option to White in the Contents section at the top of the dialog box:

Click OK when you're done to exit out of the dialog box. Photoshop fills the new layer with white. Nothing will seem to have happened in the document window since the photo on "Layer 0" is blocking the bottom layer from view, but if we look at the preview thumbnail for "Layer 1" in the Layers palette, we can see that it's filled with white, which tells us that the layer itself is filled with white:

Step 3: Change The Blend Mode Of The Photo Layer To Luminosity

With the bottom layer now filled with white, click on the top layer ("Layer 0") in the Layers palette to select it so we can change the blend mode of the layer that contains our image. At the top of the Layers palette, you'll find the list of blend modes we can choose from. By default, layers are set to the Normal blend mode. Change the blend mode to Luminosity:

By changing the blend mode to Luminosity, Photoshop blends only the brightness values (whites, blacks and all the shades of gray in between) with the white-filled layer below the image, effectively hiding the color and giving us a black and white version of the photo:

To bring the original color back at any time, all we need to do is change the blend mode for "Layer 0" back to Normal:

Instantly, the full color version of the photo returns:

Switch back to the Luminosity blend mode so we're once again seeing the black and white version of the image. Up next, we'll see how to improve our black and white conversion using two other blend modes, and how to limit the areas of the image that are affected with a layer mask!