Canon scanner CanoScan N656U User Manual

							41 chapter 4
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Index
 Contrast/Brightness button
Opens the Contrast/Brightness sheet and allows you to adjust the
brightness and contrast of the entire image.
 Gamma button
Opens the Gamma sheet and allows you to shift mid-tones so lighter
colors are lightened and darker colors are darkened.
 Histogram button
Opens the Histogram sheet and allows you to adjust tone intensity to
enhance an image that is either too light or too dark.
 Special Tone Curves buttons
Opens the Special Tone Curves sheet and allows you to adjust the tones
for one or all of the three primary colors (RGB) by selecting a special tone
curve or editing a tone curve.
Note
The Contrast/Brightness, Gamma, Histogram, and
Special Tone curves can be set even if there is no image
in the Preview Area. The setting will remain in effect
for the next image previewing or scanning. 
						

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Common Buttons
The Tone sheet settings are commonly set with the Load, Save, Reset and
All Reset buttons described below.
 Load Button
When Color Mode is set for Color(Photos) or Color (Documents), a user-
saved file (*.adc) is opened and used for color adjustment.
When Color Mode is set for Grayscale, user-saved file (*.adg) is opened
and used for gray adjustment.
 Save Button
When Color Mode is set for Color(Photos) or Color (Documents), the
user-defined settings are saved to a file (*.adc) for color adjustment.
When Color Mode is set for Grayscale, the user-defined settings are
saved to a file (*.adg) for color adjustment.
The system determines the path and file name for the saved file. The
target folder for the temporary image file cannot be changed.
 Reset button
Resets displayed settings of the channel (M, R, G or B) of the function
(Contrast/Brightness, Gamma, Histogram or Special Tone Curve)  to their
default.
 All Reset button
Resets all the settings of the channels (M, R, G and B) of all functions
(Contrast/Brightness, Gamma, Histogram and Special Tone Curve)  to
their default. 
						

							43 chapter 4
What is on the
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Glossary
Contents
Index
Contrast/Brightness Sheet
  When the Contrast/Brightness button is clicked, the Contrast/
Brightness sheet is displayed.
The shape of the tone curve changes to reflect the current Contrast/
Brightness setting for the current Channel, and the image in the Preview
Area changes to reflect the adjustment.
Channel
If you want to select one of the primary colors (RGB) for adjusting the
contrast or brightness, click the Channel down-arrow and select the
color, or leave the settings at Master to adjust all the colors.
Contrast
Drag the Contrast slider to the left to decrease the contrast of the image
or to the right to increase the contrast of the image.
Brightness
Drag the Brightness slider to the left to darken the image or to the right
to lighten the image. 
						

							44 chapter 4
What is on the
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Gamma Sheet
  When the Gamma button is clicked, the Gamma sheet is displayed.
Gamma refers to a process where mid-tones are shifted so that the
lighter colors are lightened and darker colors are darkened. For example,
let us say you scanned a photograph of a subject in a boat in a tree-lined
lake and the shadows of the trees are dark enough and the white of the
boat is light enough, but the blue in the sky, the blue of the water, and
the blue of the subjects clothing all look the same.  By increasing the
Scanner Gamma value of the image, the sky might become lighter and
the water darker, giving a better contrast to the image. The Monitor
Gamma value is a reciprocal number of the Scanner Gamma value.
Channel
If you want to select one of the primary colors (RGB) for adjusting the
gamma value, click the Channel down-arrow and select the color or
leave the settings at Master to adjust all the colors. 
						

							45 chapter 4
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Gamma (Scanner Gamma)
Drag the Gamma slider to the left or right to set the scanner gamma
value or you can type the value directly into the boxes. Entering a value
into either boxes of the scanner gamma or the monitor gamma will
display a respective value in the other box. The allowed range of values
are 0.10 to 10.00, inclusive.  The shape of the tone curve changes to
reflect the current gamma setting for the current Channel, and the
image in the Preview Area changes to reflect the adjustment. When the
Scanner Gammma value is modified, the Monitor Gamma value changes
automatically. 
						

							46 chapter 4
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Histogram Sheet
 When the Histogram button is clicked, the Histogram sheet is
displayed.
Use the histogram to enhance an image when the image is either too
light or too dark, like an overexposed or underexposed photograph.
Increasing the darker tones with the histogram improves the contrast of
the image. 
Channel
If you want to select one of the primary colors (RGB) for adjusting the
histogram, click the Channel down-arrow and select the color, or leave
the setting at Master to adjust all colors. 
						

							47 chapter 4
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Eyedroppers (Black-point, Mid-point, White-point)
Click one of the three eyedroppers then click the portion of the image in
the Preview Area that you want to sample, or enter values in the text
boxes, or drag one of the three triangles at the bottom of the graph to
adjust the value.  The shape of the tone curve and histogram changes to
reflect the current Histogram setting for the current Channel, and the
image in the Preview Area changes to reflect the adjustment.
Note
A White-point value must be larger than a Black-point,
and a Mid-point value must be between the Black-
point and White-point.
Reset
Resets the default values:
• Black-point:0
• Mid-point: 128
• White-point: 255 
						

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Special Tone Curves Sheet
  When the Special Tone Curves button is clicked, the Special Tone
Curves sheet is displayed.
Channel
Click the down-arrow and select one of the primary colors (RGB) for
adjustment or leave the setting at Master to adjust all the colors.
Select Special Curve
Click the down-arrow and select a setting from the drop-down list.
These settings are designed to solve some of the most common
problems with scanned images:  overexposure, underexposure, or poor
contrast:
•No correction
•Fix an image that is underexposed
•Fix an image that is overexposed
•Fix an image that is low contrast
•Fix an image automatically
•Edit Custom Curve 
						

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Editing a Special Tone Curve Directly
In the Special Tone Curves graph you can edit the curve directly.
1.Click on the curve and drag each curve anchor point until the
desired effect is achieved.
2.To remove an anchor point altogether, drag the anchor point off
the graph area.  
						

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Note
Here are some hints for editing curves:
•Curve handles are drawn on a white background
as a red dot to signify that they are editable. When
the cursor is over the handle, it changes to a
crosshair.
•Curve end points can be selected and dragged to
any point in the curve but cannot be deleted.
•Up to 15 points can be added to a curve by
clicking anywhere in the curve box.
•If you drag a point outside of a curve box, it will be
deleted from the curve and a new curve will form
with the remaining points.
•The x and y axes on the curve chart represent the
input image color and output image color. When
you add a handle to the curve and drag that
handle toward the white areas, the preview image
tones are adjusted to reflect the change.
•More than one handle cannot be positioned on a
vertical line but more than one handle can be
positioned on a horizontal line so you can have
several handles on a horizontal line.