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In an earlier tutorial we used Lab mode to temporarily remove colour information from an image in order to sharpen it without bringing in unwanted effects in the colour information. This time we'll use a similar technique to reduce noise.
First we'll open a reasonably noisy image. Anything taken at ISO 400 or above will probably display more noise than you would want. Step 1:
Open image in Photoshop. This is part of an image of the Vittorio Emanuele II monument, Piazza Venezia, Rome. It was taken with a digital compact and is quite noisy. 
Step 2:
Click Image > Mode > Lab Color 
Step 3:
Select the Lightness Channel 
As you can see below, this leaves us without any colour information. 
Step 4:
Select Smart Blur Filter 
Step 5:
Apply Smart Blur to taste. The setting shown below are only for illustration and you may find that other settings work better for you. Experiment until you're happy with the results. Click OK when done. 
Once you've applied your blur, you'll see the results in the Lightness Channel. It should look smoother than the original. 
Step 6:
Now we need to bring the colour back in. Click on the Lab Channel. 
The colour image is now displayed. 
Below you can see the before and after.
Unless you're doing more work in Lab Mode, don't forget to switch back to RGB.
Click Image > Mode > RGB Color See http://www.malahidecameraclub.com/joomla/images/stories/lab_noise/noise.atn for an action to automate this task. Author: Colm Gallagher Discuss this article on the forums. (1 posts) |
