Understanding color adjustments, Before making color and tonal adjustments, Correcting images – Adobe Photoshop CS4 User Manual
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USING PHOTOSHOP CS4
Color and tonal adjustments
Last updated 1/10/2010
Understanding color adjustments
Before making color and tonal adjustments
The powerful tools in Photoshop can enhance, repair, and correct the color and tonality (lightness, darkness, and
contrast) in an image. Here are some items to consider before making color and tonal adjustments.
•
Work with a monitor that’s calibrated and profiled. For critical image editing, calibration and profiling is essential.
Otherwise, the image you see on your monitor looks different on other monitors or when printed.
•
Plan to use adjustment layers to adjust the tonal range and color balance of your image. Adjustment layers let you
go back and make successive tonal adjustments without discarding or permanently modifying data from the image
layer. Keep in mind that using adjustment layers adds to the file size of the image and demands more RAM from
your computer. Accessing the color and tonal commands in the Adjustments panel automatically creates
adjustment layers.
•
If you don’t want to use adjustment layers, you can apply adjustments directly to an image layer. Remember that
some image information is discarded, when making a color or tonal adjustment directly to an image layer.
•
For critical work and maximum preservation of image data, it’s best if the image you work with is 16 bits per
channel (16-bit image) rather than 8 bits per channel (8-bit image). Data is discarded when you make tonal and
color adjustments. The loss of image information is more critical in an 8-bit image than a 16-bit image. Generally,
16-bit images have a larger file size than 8-bit images.
•
Duplicate or make a copy of the image file. Working on a copy of your image preserves the original in the event you
want to use the image in its original state.
•
Remove any flaws such as dust spots, blemishes, and scratches from the image before making color and tonal
adjustments.
•
Open the Info or Histogram panel in Expanded view. As you evaluate and correct the image, both panels display
invaluable feedback on your adjustments.
•
You can make a selection or use a mask to confine your color and tonal adjustments to part of an image. Another
way to apply color and tonal adjustments selectively is to set up your document with image components on
different layers. Color and tonal adjustments are applied to only one layer at a time. Only the image components
on the targeted layer are affected.
Correcting images
Here is the general workflow you follow when you correct the tonality and color of an image:
1
Use the histogram to check the quality and tonal range of the image.
2
Make sure that the Adjustments panel is open to access color and tonal adjustments. Click an icon to access the
adjustments described in the following steps. Applying corrections from the Adjustments panel creates an
adjustment layer, which gives you more flexibility and doesn’t discard image information. See “
About adjustment and fill layers
3
Adjust the color balance to remove unwanted color casts or to correct oversaturated or undersaturated colors. See
“
4
Adjust the tonal range, using either the Levels or Curves adjustments.