Adobe 29180155 - Photoshop Elements 4.0 User Manual page 132

Adjusts the contrast and color by identifying shadows, midtones, and highlights in the image,
Auto Color Correction
rather than in individual color channels. It neutralizes the midtones and clips the white and black pixels using a
default set of values.
Automatically detects and repairs red eyes in an image.
Auto Red Eye Fix
Note: You can use an auto command on an entire image, or you can correct a portion of an image by first making a
selection with one of the selection tools.
About histograms
You can use the histogram to analyze the image's tonal distribution to see if you need to correct it. A histogram shows
the distribution of an image's pixel values in a bar chart. The left side of the chart shows the values of the image
shadow (starting at level 0), and the right side shows the highlight (level 255). The vertical axis of the chart represents
the total number of pixels with a given level.
You can view an image's histogram in the Histogram palette. Histograms are also available in the Levels dialog box
and the Camera Raw dialog box. You can update the histogram as you work so that you can see how your adjustments
are affecting the tonal range. When the cached data warning icon appears, click it to refresh the histograms data.
A
Histogram palette
A. Channel menu B. Palette menu C. Uncached Refresh button D. Cache Data Warning icon E. Statistics
If many pixels are bunched up at either the shadow or highlight ends of the chart, it may indicate that image detail
in the shadows or highlights may be clipped—blocked up as pure black or pure white. There is little you can do to
recover this type of image. If you are working with a scanned image, you can try rescanning to produce a better tonal
range. If your digital camera can display an image histogram, check it to see whether your exposure is correct and
make exposure adjustments if necessary. See your camera's documentation for more information.
The histogram may show that an image is not using the full tonal range available if some pixels aren't available in the
shadows and highlights. You can fix an image with limited tonal range by stretching the tonal range using either the
Levels command or one of the Enhance > Auto commands.
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ADOBE PHOTOSHOP ELEMENTS 4.0
User Guide
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