Image on the left is the result of our tutorial and image on the right is simple grayscale conversion mode. We can see that the image on the left got the valve and leaf a little higher contrast from its background.
We can further enchance the black and white contrast by using layer blending. Select your 'my_black_and_white' document and press ctrl+j. It will copy the image and place into new layer. We are going to use this new layer to blend into its original image (read Layer Mode Tutorial for more information).
Use the following setting for the new layer blending.
Soft Light and Opacity 77% for the new layer. The reason we use soft light is because it make what is white whiter and dark remain dark.
Because we want to access the channel informaiton, we have to change the image mode from 'Multichannel' to 'Grayscale', select the image on the left(color) and go to menu 'Image'->'Mode'->'Grayscale'. Access channel layer palette and press ctrl+1, ctrl+2 and ctrl+3 to go through all the channel. You will see all three channels value in black and white mode. (If you see the channels display in color, turn it off by going to preferences dialog ctrl+k->Interface->check Show Channels in Color).
Depend on what image you working on, I found that Green channel work best for this example. Because the shape of valve and leaf can be little more distinguish from background.
We want to extract this green channel value into independant image document. On the channels layer palette, right click on the green layer and select 'Duplicate Channel...'.
Under Destination section, change the Document to New, and enter the name 'my_black_and_white'. Click OK to duplicate the channel into new document. The image should look like the one on the right.
First we need a simple grayscale mode image for us to compare our work. What we trying to achieve in this tutorial is to beat the standard grayscale mode conversion. Begin by duplicating the image and convert it into grayscale mode, go to menu 'Image'->'Duplicate...', leave the default setting in the Duplicate Image dialog and press OK.
Now convert the previously created 'black_and_white_01 copy' image to grayscale by go to menu 'Image'->'Mode'->'Grayscale', press OK when asked if you want to discard the color information.
Now we got something to compare our work. We trying to convert the image on the left to black and white image that look better than the simple flat contrast grayscale mode image on the right.
The first technique we going to introduce here is the simplest but effective way of converting image or photo into black and white color.
We are basically picking one of the three color channels and see if one of them looking better than a simple grayscale mode conversion, and then do some simple layer blending to enchance the contrast of the black and white image.
The image on the left taken from the National Park of Malaysia. We will be using the photo on the left to do our color to black and white conversion. Download the PSD project file here.