How to Measure and Compare Pixel Values
How to Optimize the Tonal Range
How to Improve Contrast with Curves
How to Use the Dodge, Burn, and Sponge Tools
How to Sharpen Images
How to Use Blur to Sharpen
How to Convert Images to Grayscale
The tasks in this part look at how to work with image tonality. As far as digital images are concerned, tonality refers to the grayscale values from 0 to 255 that differentiate the image pixels. Tonality is black and white and shades of gray; tonality is a histogram, a halftone, salt and pepper, the I Love Lucy show, and a dark foreboding sky hanging low over the concrete streets of New York.
I'm using this somewhat poetic introduction to emphasize the fact that tonality is one of the most expressive elements of an image. It can establish a full-contrast range, create a feeling of darkness and danger, or obliterate outlines in the form of fog or mist. If you want to create a strong feeling in an image, consider exaggerating the tonality in some way.
In addition to its expressive qualities, tonality also helps to sharpen an image, even as it increases the contrast. Sharp details, rich and complex color, and the look of texture are all created by manipulating black, white, and shades of gray.
The tasks that follow help you to optimize any given file, making it the best it can be. You can take a dark or underexposed image and make it usable with curves and a few filters. Even better, you can take an image that already looks pretty good and make it a real winner.