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Color tab
This tab is used to control the color balance of the preview
and scan. It lets you specify the image brightness,
the color balancing, the black and white points and the color space.
- Image brightness
- You can increase the overall brightness of
the image by increasing this option. The darker areas are increased
in intensity more than the brighter areas, and the color hues are
kept constant when the intensity is increased.
- Color balance
- Use this option to set the type of color
balance you want for each image. If you image is dominated by
a single color or bright colors (i.e. flowers or foliage), use
the auto levels option, otherwise use the White balance option.
- None
- - The black and white points aren't used at all, and
the image is only corrected for the CCD's color response
(if the Media type option is set to Image) or by the
film's color response.
- Neutral
- - Both the black and white points are used to
stretch the image's intensity range. However, the relative
proportions of red, green, and blue are kept constant.
- Tungsten
- - Both the black and white points are adjusted
to compensate for an image lit by tungsten light (i.e. a normal
incandescent light bulb). This removes the reddish cast from
indoor pictures taken without a flash.
- Fluorescent
- - Both the black and white points are adjusted
to compensate for an image lit by fluorescent light. This removes the
greenish cast from indoor pictures lit by fluorescent lights or
lit by flash.
- Night
- - Both the black and white points are adjusted
to compensate for an image taken at night. The white balance
is determined from the darkest 10% of the image, which
often produces the best results when images have bright
fluorescent or incandescent lights that are greenish
or yellowish.
- White balance
- - VueScan analyzes the image and adjusts it
to make the color balance look like the scene is lit by daylight.
- Auto levels
- - This is a simple mapping of the darkest
color to 0.00 intensity and the brightest color to 0.95 intensity.
- Black point (%)
- The black point is used by the color balance
algorithm and is computed by using the histogram of each color
in the image. Use this option to leave the black point at
the minimum intensity (0%), or to choose the black point such that
some percentage of the pixels in the image are below the black
point.
- Black point red/green/blue
- This option lets you set the
black point manually. Note that these values are in linear space,
not gamma corrected space, so the only practical way to use
these values is to do a scan with the "Auto black point" option
turned on, then turn it off to lock in these values.
- White point (%)
- The white point is used by the color balance
algorithm and is computed by using the histogram of each color
in the image. Use this option to leave the white point at
the maximum intensity (0%), or to choose the white point such that
some percentage of the pixels in the image are above the white
point.
- White point red/green/blue
- This option lets you set the
white point manually. Note that these values are in linear space,
not gamma corrected space, so the only practical way to use
these values is to do a scan with the "Auto white point" option
turned on, then turn it off to lock in these values.
- Color space
- Use this option to set the color space for
the final image. A color space is a combination of color
primaries and white point. If you're using Photoshop, you'll
probably want to use the Adobe RGB color space, otherwise
the sRGB setting is probably best.
If you're using Photoshop, you'll probably also want to enable
writing the ICC profile to the TIFF and/or JPEG file by using
the TIFF profile and/or JPEG profile option in the Files tab.
- Gamma
- This option changes the image contrast. Use
1.8 if you change the color space to Apple RGB, ColorMatch RGB
or ProPhoto RGB. All other color spaces use a gamma of 2.2
by default. Note that changing this option changes the image
but doesn't change the embedded ICC profile.