STEP 2 - GREYSCALE

The Lab colour mode made it easy to select only the lightness values in the image, but all we've really done here is turned off the colour information. We need to make sure the colour is removed completely. We also need to convert the image into a more practical colour mode, one that printers and other electronic devices understand, since most won't know what to do with an image that's using Lab colour. We can solve both of these problems at once by converting the image to the Grayscale colour mode. To convert the image from Lab to Grayscale, simply go back up to the Image menu, select Mode once again, and then select Grayscale:

Photoshop will pop open a warning box asking if you're sure you want to discard the other channels. Click OK:

Again, nothing will seem to have happened to the image in the document window, but if we look at our Channels palette, we can see that our image is now made up of a single Gray channel, just as we saw in the Grayscale tutorial, and all of the color information has been completely removed:

STEP 4 - SAVING:

If you want to have the original colour copy of the photo, if you save the image at the point it is at, and overwrite the original saved on your computer, the colour information will be lost forever. If you want to save your black and white version without losing the original color version, be sure to select Save As from under the File menu at the top of the screen and save the black and white version under a different name.

SHARPENING

Sharpening is something that almost any image can benefit from. Like saturation, it can easily be ignored or overdone if you’re not careful. When done right, it’s a subtle change that results in a big improvement.

It seems that there are many ways to sharpen a photo, and the most common is Photoshop’s Unsharp Mask. It’s a fine tool for most cases, but it can produce terrible results when used incorrectly or without caution.

STEP 1 - GETTING STARTED

The RGB color mode is the most common to work with, so I’ll assume that most of us use this as our default. We can still work in RGB even though we’re doing adjustments in LAB color mode, it’s just a little extra work. So open up your image as you normally would and basically process the entire image until you’re happy with it.

Sharpening should occur as the very last step in your workflow for two main reasons: 1) It’s a very localized adjustment of brightness and any further processing will exaggerate it beyond your original intent, and 2) It’s a destructive process, so we’ll be using a copy layer for the sharpening — and if you stack adjustments on top of those layers, it makes life very difficult if you choose to go back and rework the sharpening. Make a copy of the visible image by doing a “Stamp Visible” command, press Shift+Ctrl+Alt+E (Windows) or Shift+Command+Option+E (Mac OS). This gives us a single layer that contains all of the underlying adjustments we’ve applied. Now take this layer and duplicate it to a new document. Once in that new document, change the colour mode to “LAB”.

STEP 2 - SHARPENING PART:

The lightness channel contains all of the light and dark tones in the image while avoiding any noise caused by the color channels. Sharpening works by darkening the darks and lightening the lights at their boundaries. Any color noise will cause noisy sharpening. In this example, I’ll show the Unsharp Mask to sharpen the image. You could use whatever method you prefer in place of that.

Switch to the channels palette and select “Lightness”. The “A” and “B” channels should be deselected and your image should look like a black and white photo. Now, apply your sharpening directly to that channel. For the Unsharp Mask, you can find it under; Filter > Sharpen > Unsharp Mask. Every image requires different settings, so don’t just assume that those numbers when you first select are the best for your image. Once you get the sharpness where you like it, apply the filter and reselect the “LAB” channel in your palette.