Basic Photo Corrections
- May 15, 2006
- Strategy for retouching
- Resolution and image size
- Getting started
- Straightening and cropping an image
- Using automatic adjustments
- Adjusting the tonal range
- Removing a color cast
- Replacing colors in an image
- Adjusting lightness with the Dodge tool
- Adjusting saturation with the Sponge tool
- Applying the Unsharp Mask filter
- Compare the manual and automatic results
- Saving the image for four-color printing
- Review questions
- Review answers
Adobe Photoshop and Adobe ImageReady include a variety of tools and commands for improving the quality of a photographic image. This lesson steps you through the process of acquiring, resizing, and retouching a photo intended for a print layout. The same workflow applies to Web images.
In this lesson, you’ll learn how to do the following:
- Choose the correct resolution for a scanned photograph.
- Crop an image to final size.
- Adjust the tonal range of an image.
- Remove a color cast from an image Auto Color correction.
- Adjust the saturation and brightness of isolated areas of an image using the Sponge and Dodge tools.
- Apply the Unsharp Mask filter to finish the photo-retouching process.
- Save an Adobe Photoshop file in a format that can be used by a page-layout program.
This lesson will take about an hour to complete. The lesson is intended for Adobe Photoshop, but information on how to perform tasks in Adobe ImageReady is included where appropriate. Because ImageReady permanently converts 16-bit files into 8-bit files when you open them, it’s recommended that you do this lesson in Photoshop.
If needed, remove the previous lesson folder from your hard drive, and copy the Lesson03 folder onto it. As you work on this lesson, you’ll overwrite the start files. If you need to restore the start files, copy them from the Adobe Photoshop CS Classroom in a Book CD.
Strategy for retouching
You can retouch photographic images in ways once available only to highly trained specialists. You can correct problems in color quality and tonal range created during the original photography or during image scanning. You can also correct problems in composition and sharpen the overall focus of the image.
Photoshop provides a comprehensive set of color-correction tools for adjusting the color and tone of individual images. ImageReady has a more basic set of color-correction tools, including Levels, Auto Levels, Brightness/Contrast, Hue/Saturation, Desaturation, Invert, Variations, and the Unsharp Mask filter.
Organizing an efficient sequence of tasks
Most retouching follows these eight general steps:
- Duplicating the original image or scan. (Always work in a copy of the image file, so that you can recover the original later if necessary.)
- Checking the scan quality and making sure that the resolution is appropriate for the way you will use the image.
- Cropping the image to final size and orientation.
- Repairing flaws in scans of damaged photographs (such as rips, dust, or stains)
- Adjusting the overall contrast or tonal range of the image.
- Removing any color casts.
- Adjusting the color and tone in specific parts of the image to bring out highlights, midtones, shadows, and desaturated colors.
- Sharpening the overall focus of the image.
Usually, you should complete these processes in the order listed above. Otherwise, the results of one process may cause unintended changes to other aspects of the image, making it necessary for you to redo some of your work.
Later in this book, you’ll get experience using adjustment layers, which is another technique that gives you great flexibility to try out different correction settings without risking damage to the original image.
Adjusting your process for intended uses
The retouching techniques you apply to an image depend in part on how you will use the image. Whether an image is intended for black-and-white publication on newsprint or for full-color Internet distribution affects everything from the resolution of the initial scan to the type of tonal range and color correction that the image requires. Photoshop supports the CMYK color mode for preparing an image to be printed using process colors, as well as RGB and other color modes. ImageReady supports only RGB mode, used for on-screen display.
To illustrate one application of retouching techniques, this lesson takes you through the steps of correcting a photograph intended for four-color print publication.
For more information about CMYK and RGB color modes, see Lesson 20, “Producing and Printing Consistent Color.”
Image cropped and retouched
Image placed into page layout