Color tab

This tab is used to control the color balance of the preview and scan. It lets you specify the image gamma (similar to contrast), the color balancing, and the black and white points.

Image gamma

You can set the gamma of the final image by setting this option. Most PC users should use 2.2, but if you want to make the image seem brighter or get more detail from dark areas, use a larger value for gamma (such as 2.6). If the image seems too bright or washed out, try using a smaller value for gamma (such as 1.8).

Before using image gamma to change the image brightness, try using the black and white points to accomplish this.

If you're scanning slides with underexposed portions, try setting this option to a value between 3 and 6 to bring the detail out of the dark parts. You might also try using the Faded image or Faded slide options for dark slides.

Color balance

Use this option to set the type of color balance you want to do to each image:

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 Correct for option is set to None) 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.

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 black point to 0.00 intensity and the white point 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.