Think like a sculptor and shape your tones for ideal B&W conversions.

Often, when confronted with the need for a B&W version of a color image, the process of conversion is treated as an afterthought. There may be some thought as to what the best method will be or one may simply select the default tool in Photoshop and play around with a few slider settings. I propose a different approach, that is related to my 10-Channel Workflow, and that takes advantage of the inherent channel structure of a color image to selectively control the tonal rendering of specific areas of the image.

Let us examine this approach in this studio image (download image here):

Blond Angel

Lovely lighting caresses our beautiful model

This image seems quite nice in color and should pose no problems converting into B&W. One can use the standard mode change to grayscale and arrive at a perfectly acceptable B&W version…

Standard B&W

The standard grayscale conversion is very similar to the default setting for the B&W adjustment layer.

If we are willing to do a little more work we can create a more idealized version. The key is to leverage the different grayscale renderings of the separate RGB channels to create a more “sculpted” look. Let us start by examining the individual channels. Go to the channels panel and click on the Red, Green, and Blue channel thumbnails…

Red Channel Image

Click on the Red channel thumbnail to "see" the red channel

Green Channel Image

The green channel

Blue Channel image

The Blue channel

We can see that the Red channel is the lightest overall and the Blue channel is darkest with the Green in-between. I love the pale, luminescent quality of the Red channel but it needs a little more contrast and “shape” to be successful. It is relatively easy to combine these channels into a single version using a Channel Mixer adjustment but we can add more control by putting individual channels into layers and blend using layer masks.

Start with the Red channel by creating a Channel Mixer adjustment layer…

Adjustment Panel

Click on the Channel Mixer icon in the Adjustments panel.

Select “Black & White with Red Filter (RGB)” from the presets drop down menu at the upper right of the Channel Mixer panel.

Channel Mixer Adjustment

Select "Black and White with Red Filter" from the presets menu

This will give you a grayscale rendering representing 100% of the Red channel. Next we need to add the Green channel into the next layer.

Red Channel Effect

After you have the "Red" Channel Mixer in place return to the Adjustments Panel.

Click on the arrow icon at the lower left of the Channel Mixer Adjustments panel to return to the Adjustments home. The select the Channel Mixer icon again, and once the Channel Mixer Adjustment is in place select the “Black & White with Green Filter (RGB) preset!

Green Filter Preset Menu

After you have the Channel Mixer in Place, select the Green Filter preset.

You will notice that NOTHING HAPPENS! That is because the image is now the same in all channels after the “Red” Channel Mixer adjustment, so displaying the green channel at 100% is no different that the red channel at 100% — this fact has escaped the attention of other “experts” who have promoted this method of B&W control. In order to really make this work, you have to employ a little trick using advanced blending options.

Go to the Layers panel and select “Blending Options…” from the Layers options fly-away…

Blending Options

Select "Blending Options" from the Layer panel options fly-away.

You will be presented with the Layer Style dialog – we’re interested in the center “Advanced Blending” portion of the dialog. Select “Deep” from the “Knockout” fly-away menu.

Blending Options Dialog

Select "Deep" from the "Knockout" drop down menu

This option tells the Channel Mixer adjustment layer to reach down to the background layer to get at the Green channel from the original color image. In effect, we now have the Green channel on top of the Red channel, and you’ll notice that the image has changed and now looks like the Green channel. The next task is to control the Green channel layer with a layer mask!

First, hide the layer by inverting the Green Channel Mixer  layer mask to black. Click on the Green Channel Mixer adjustment layer mask thumbnail to select it…

Selecting Layer Mask

Select the layer mask by clicking on the layer mask thumbnail.

Then select Image-> Adjustments-> Invert to turn the mask black. This hides the darker “Green” layer in preparation for the next step.

Invert Image

Select: Image-> Adjustments-> Invert to turn the mask black.

Now I’ll get a soft brush and paint into the image over shadow areas to reveal the darker tones of the Green channel. The idea is to think like a painter and selectively darken certain areas to “sculpt” the image. The effect is more subtle and more convincing than simply painting in a darkening adjustment because the green channel already has a full range of light and dark tones so the transitions from painted to un-painted areas are less detectable after painting. You can think of this as painting in more contrast in the darker areas.

Brushing in the Darker channel

Use a brush with white to paint in the darker tones from the "Green" channel layer.

In the screenshot above, I am painting in a shadow at the cheek. Below I’ve finished the head…

Finhed head

Other shadows darkened, leaving a nice highlight for the nose.

The head now has a slightly more three dimensional look – now I’d like to darken the lips. The green channel is too dark and flat looking in the lips but the blue channel looks much better so I’ll put a blue Channel Mixer adjustment layer on top just for the lips.

Blue Channel Mixer Layer

Place a "Blue" Channel Mixer adjustment at the top of the layer stack.

Now simply paint over the lips with white (make sure you’ve inverted the layer mask first) to reveal the Blue channel version of the lips.

Blue Channel Lips

The Blue channel lips look completely different than just a darker version of the red lips.

Now lets move on to the rest of the figure — here I’ve darkened the whole chest by painting into the Green Channel Mixer layer mask with white.

Darken Chest

First darken the chest by painting into the Green layer mask.

After changing the paint color to black I put back highlights on the breasts…

Highlighted Breasts

Painting back into the image with black hides the darkening effect and puts highlights on the breasts.

The idea is to follow this procedure to build up the shadows with the green channel and keep highlights from the red channel. The result is a subtle sculpting effect that is very natural looking but still idealized. Compare the default B&W, on the left, with this “sculpted” version, on the right.

Side by Side

Default grayscale conversion on the left vs Sculpted version on the right.

The final result blends the best parts of each channel from the color image to create a B&W rendering that goes beyond a simple global adjustment.  Things get very interesting when you apply this enhanced tonal rendering back into the original color image:

Side by Side Color

As before, original color is on the left and the enhanced tone (from this B&W exercise) is on the right.

In this case, I achieved this result by duplicating the original color Background layer to the top and changing the layer apply mode to “Color” ((select from the fly-away menu under Layers tab).

Color Apply

Apply the color from a dupe of the original layer at the top – change the mode to "Color"

The B&W tonal rendering has had a glamorizing effect in this  image but the same principal can be applied for other uses. I have some related posts on Luminosity blending here:

Lightening Dark Skin with Luminosity Blending 

Luminosity Blending-1

Luminosity Blending-2

I will be covering this and other advanced glamour techniques in my upcoming workshop for Light Photographic Workshops in Los Osos March 14th thru 18th, 2012 – Classic Hollywood Portraiture —Learn the classic studio portraiture of the Hollywood masters from a contemporary Hollywood master. I will guide students in studio lighting and and portrait photography techniques, including post processing work and retouching. Learn to create the look of a bye-gone era as seen in the hit movie “The Artist” in B&W and color.

Topics include:

• Classic Hollywood lighting – the George Hurrel “look”
• Contemporary studio lighting techniques
• Posing for headshots and figures
• B&W conversion techniques
• Color Toning – various techniques for adding color tones to B&W images
• Complete beauty retouching techniques
• The new skin smoothing technique that preserves actual skin texture while removing defects. on inkjet printers in the classroom.




Thank you for sticking with this rather long post – my first new tutorial for 2012. Stay tuned for more cool digital imaging blog posts in the near future.