Canon scanner CanoScan N650U User Manual

41 chapter 4
What is on the
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 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...

42 chapter 4
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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...

43 chapter 4
What is on the
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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...

44 chapter 4
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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...

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...

46 chapter 4
What is on the
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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...

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...

48 chapter 4
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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...

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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.  

50 chapter 4
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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...