Black and white conversion with local area contrast

11Dec07

Over the years I have gone through all the different ways of converting colour images to black and white. In the spirit of seasonal goodwill and sharing, I’ll tell you how I go about it in a pretty painless way.

It is generally considered the best way to convert the image to monochrome using the LAB conversion. Yes, you can use greyscale, gradient map and desaturation, but they all lack something and, by far, I prefer the LAB method.

If you are not using Photoshop (v7 onwards) then this article is an interest piece rather than a tutorial.

Here’s the original colour image I am working with

Select, from the menu, Image > Mode > Lab color

In the Channels Palette, click select the Lightness channel, or press Ctrl 1

Select the image, Ctrl A and copy Ctrl C

Now, convert the image back to RGB, so Image > Mode > RGB Color

In turn, select each of the Red, Green and Blue channels and for each, Paste Ctrl V in the selection.

You now have a monochrome image.

To add a little depth, I now duplicate the layer twice.

To the first new layer, I change the layer drop down from ‘Normal’ to ‘Color Burn’ and set the opacity to 12.

And the second new layer, I change the layer drop down from ‘Normal’ to ‘Soft Light’ and, again, set the opacity to 12.

Here’s the image and what the layer menu should be looking like (I’ve renamed the layers to be nice)

If you were recording a macro, stop it here so it leaves you with a background layer, a color burn and soft light layer.

Play with both those opacities, until you are happy with the tonal range in the image.

Now flatten it. A major improvement, yes?

It’s not over, though.

When you click on Auto Levels on any image, colour or monochrome, Photoshop attempts to find the darkest and lightest states of the image and then even out the tonal range between the two extremes. This is an adequate method, but quite often leaves areas of the image with low contrast and darkened because the level change was applied uniformly to the entire colour spectrum. What if we could combat this failing by improving the levels for each and every part of the image? I’m not going to explain the technicalities right now, but there is a handy action by a pbaser, Jay, to do just this. Find the photoshop action Local Contrast v1.1 here.

And with the Local area contrast action applied (I used Local Area Contrast 25px), we get a much more impressive conversion.

Enjoy

Would anyone like to know how I sharpen images?

 

Filed under: Photography, Tutorial   |  Leave a Comment