Canon printer PIXMA MG6821 User Manual

Brightness
Adjust the image brightness.
Move 
 (Slider) under  Brightness to the left to darken and right to brighten the image. You can also
enter a value (-127 to 127).
DarkenedOriginal imageBrightened
Note

Adjusting HistogramYou can adjust the image color tone by using a graph (histogram) showing brightness distribution, via 
(Histogram) in ScanGear (scanner driver)'s  Advanced Mode tab.
Note

(1) Bright area(2) Dark area(3) Whole imageMore data is distributed to thehighlight side.More data is distributed to the shadow side.Data is widely distributed between thehighlight and shadow.
Adjusting Histograms (Using the Slider)
Select a  Channel , then move 
 (Black-point Slider) or  (White-point Slider) to specify the level to be
set as the shadow or highlight.

Moving the Mid-point SliderMove the Mid-point Slider to specify the level to be set as the middle of the tonal range.
Images with more data distributed to the highlight side
Move the Mid-point Slider toward the highlight side.
Images with more data distributed to the shadow side
Move the Mid-point Slider toward the shadow side.
Adjusting Histograms (Using the Droppers)
When you select a  Channel and click the Black-point, Mid-point, or White-point Dropper, the mouse
pointer on the preview image changes...

Adjusting Tone CurveYou can adjust the brightness of an image by selecting the type of graph (tone curve) showing the balance
of tone input and output, via 
 (Tone Curve Settings) in ScanGear (scanner driver)'s  Advanced Mode
tab.
Note

Adjusting Tone Curve
In  Select Tone Curve , select a tone curve from  No correction, Overexposure , Underexposure , High
contrast , Reverse the negative/positive image , and Edit custom curve .
No correction (No adjustment)
Overexposure (Convex curve)
The midtone data of the input side is stretched toward the highlight of the output side, resulting in a bright-
toned image when viewed on a monitor.
Underexposure (Concave curve)
The midtone data of the input side is stretched toward the shadow of the...

Edit custom curve
You can drag specific points on the Tone Curve to freely adjust the brightness of the corresponding areas.
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Setting ThresholdYou can sharpen text in a document or reduce show-through in newspapers by adjusting the threshold level
via 
 (Threshold) in ScanGear (scanner driver)'s  Advanced Mode tab.
Note

ScanGear (Scanner Driver) Screens
Basic Mode Tab
Advanced Mode Tab
Input Settings
Output Settings
Image Settings
Color Adjustment Buttons
Preferences Dialog Box
Scanner Tab
Preview Tab
Scan Tab
Color Settings  Tab
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