How do I change a single layer to grayscale in Photoshop CS4?

Question

I know you can have the whole image turn grayscale: Image > Mode > Grayscale, but what if I only want to make specific layers grayscale? There's gotta be an easier way than pulling out the layers you want to turn grayscale to a new image, grayscaling, and then pasting them back in.

Answer 1

Depends...on why you want to go greyscale.

To create identical layer in greyscale...

Layer > Duplicate Layer > Hue/Saturation > DeSat

To create adjustable greyscale layer...

Layer > Duplicate Layer > New Adjustment Layer > Hue/Saturation > DeSat > (when done) Merge Layer

For tons more control...

Layer > New Adjustment Layer > Black & White. You can tweak every color channel in greyscale. Very cool.

For FABULOUS toning of B/W images with a little less work than B/W layer. (This is my secret, guard with your life)

**Layer > New Adjustment Layer > Hue/Saturation > Blend Mode Color:

Layer > New Adjustment Layer > Hue/Saturation > Sat -100 >

Go back to first Hue/Sat Layer (the one in color blend mode) double click on layer window to open then tweek the Hue. Viola, instant Zone system!

To answer your question, click on the layer you want to greyscale and use any of these methods, then select your adjustment layers and active layer and merge down through Layer > Merge Down or on a Mac Command + E.

Answer 2

There are many ways to convert a single layer to grayscale. Non-destructively there is the black and white adjustment layer as you say, as well as the hue and saturation adjustment layer (set saturation to 0), threshold adjustment layer or channel mixer adjustment layer.

My preferred method is the channel mixer as it takes account of colours in the final grey levels (as does the black and white adjustment later) allowing precise control over exactly how much of each channel you can take. I find it useful to first look at the red, green, and blue channels in isolation to get a good idea of which looks the best and should therefore dominate for a particular image.

Answer 3

The simplest approach I know of is to Desaturate the layer. Photoshop even provides a handy one-step command for it:

Image > Adjustments > Desaturate

Equivalent is a keyboard shortcut: CTRL-SHIFT-u.

Reference: Desaturate Colors

Answer 4

Well after some playing around I discovered Layer > New Adjustment Layer > Black and White. Just pop that on top of the layers you want to be grayscaled and viola!

Answer 5

I guess the simplest way is to duplicate the layer (right click on the layer in the layer tab and then select duplicate layer) and then turn this individual layer into grayscale as you mentioned before.

My question however is this: Why do you want to turn a single layer into grayscale if you will eventually have to either blend the layers together or completely flatten the image. Either way if one layer is grayscale and the one sitting on top is not you will not obtain any results.

If you want to be able to control luminace and saturation of individual colours and say have the entire image black and white but only the red colour visible you can do it easily in Lightroom 3 without having to work on layers.

Here is one of my images processed that way

Please tell me if that gets you any closer to the answer.