B&W Conversion Theory

rutt · January 18, 2006

This thread as a place for discussion of my tutorial on the subject. See: http://dgrin.smugmug.com/gallery/1134301

Andy · January 18, 2006

Everone is waiting with breathless anticipation![imgr]http://dgrin.smugmug.com/photos/14326025-L.gif[/imgr]

flyingdutchie · January 18, 2006

Some additional questions:

rutt wrote:

This thread as a place for discussion of my tutorial on the subject. See: http://dgrin.smugmug.com/gallery/1134301

Using the channel mixer, the sum of the percentages in the three channels usually adds up to 100%.

However, there is also another slider there that adds lightness overall. How does this one interact (number-wise/mathematically and visually) with the overall lightness?

When is it good to have the sum of the three percentages add to to more than 100% or less than a 100%?

Has anyone any 'recipes' when using the channel mixer (with or without using it through an adjustment layer) to get certain B&W effects? (high contrast, glow, 'gritty-ness', etc.)

I would love to hear some creative ways of making B&Ws!

-- Anton.

rutt · January 18, 2006

I like to stack the channels in separate layers. This gives a lot more flexibility than the channel mixer because different blending options, such as darken and multiply are available. Layer masks and curves are also available with this method.

As my tutorial emphasized, the first step is to decide how each color maps into B&W. Should that hat be lighter or darker than the face? What about red hair?

Once these issues are resolved, then there is plenty of time to worry about overall contrast, grain, sharpness, &etc.

Gary Glass · January 18, 2006

rutt wrote:

I like to stack the channels in separate layers. This gives a lot more flexibility than the channel mixer because different blending options, such as darken and multiply are available. Layer masks and curves are also available with this method.

I don't understand how you do that, Rutt. Could you explain in a bit more detail? Or possibly extend your tutorial?

zigzag · January 18, 2006

Anyone ever do this? I'm going by memory, so I hope I don't screw it up, but even I was able to comprehend this one:

Take photo.

Make a duplicate layer and desaturate, but set blending mode to color.

Make another duplicate layer sandwiched between the original and the first layer. Now play with the hue slider in the hue/saturation control for that layer.

The below was made with this method:

rutt · January 18, 2006

Gary Glass wrote:

I don't understand how you do that, Rutt. Could you explain in a bit more detail? Or possibly extend your tutorial?

Make three layers. Name them Red, Green, Blue. Select the layer named red (with all it's channels selected.) Image->Apply Image and choose the red channel of the background layer, normal blending mode, 100% opacity. Now repeat for each of the other layers, applying each channel of hte background image to the appropriate layer. When you are done, you can play with the blending options of the layers, opacity, and stacking order.

rutt · January 18, 2006

zigzag wrote:

Make a duplicate layer and desaturate, but set blending mode to color.

Make another duplicate layer sandwiched between the original and the first layer. Now play with the hue slider in the hue/saturation control for that layer.

This is pretty nice. Try it with the stripes to see how it allows you to change the mapping of hue to shade.

david_h · January 18, 2006

rutt wrote:

This is pretty nice. Try it with the stripes to see how it allows you to change the mapping of hue to shade.

I like it too. I thought I knew all the B&W tricks, but I've never tried this one.

Jeroen · January 20, 2006

I usually work with adjustment layers.

Here is a typical layer order, the numbers show my workflow:

5 Brightness & contrast or levels (on top)
2 Hue and Saturation (to completely desaturate the entire pic)
4 Selective color (with mask)
3 Selective color (with mask)
1 Original colour piece (background)

This gives me 2 advantages.
First, by using adjustment layers, I can use masks to make a layer work on just specific parts of the piece. I use a Wacom tablet to paint the masks.
Second, it leaves all colour info intact. This gives me the abillity to influence parts I couldn't have done when I would have changed the whole thing to BW at the start. For instance correcting all Cyan to get a more dramatic sky...

Scarhart · January 20, 2006

flyingdutchie wrote:

Using the channel mixer, the sum of the percentages in the three channels usually adds up to 100%.

However, there is also another slider there that adds lightness overall. How does this one interact (number-wise/mathematically and visually) with the overall lightness?

When is it good to have the sum of the three percentages add to to more than 100% or less than a 100%?

Has anyone any 'recipes' when using the channel mixer (with or without using it through an adjustment layer) to get certain B&W effects? (high contrast, glow, 'gritty-ness', etc.)

I would love to hear some creative ways of making B&Ws!

-- Anton.

Anton,

Keeping the sum of the sliders to 100% retains the same luminosity of the original color image. You can go under 100% to lower the luminosity, over to increase it.

The magic numbers used by Photoshop pros I've studied are Red +60% Green +40% and Blue at 0%. The noise is in the Blue channel, so taking it to 0% smoothes out the image as much as possible.

Cheers,
Scott

B&W Conversion Theory

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