Canon CanoScan D660U Canon Plug-in Module CS-U3.9 User's Guide - Page 50

Adjusting the Threshold Value

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STEP 3 Adjusting the Threshold Value When the scan mode is set to black and white, the image brightness can be adjusted. The threshold value setting determines whether a halftone will be expressed as a black or a white data point. The possible threshold values range between 0 and 255. Below a given threshold value, all data is converted to black. Likewise, all data with a value above the threshold is converted to white. Accordingly, higher threshold values produce darker images while lower threshold values result in brighter images. Threshold Value = 128 (Standard) Threshold Value = 180 Threshold Value = 70 To Set the Threshold Value When the scan mode is set to black and white, click the [Tone Adjustment] button or pull down the Image menu and select [Tone Adjustment]. Drag the slidebar left or right to adjust the threshold setting. Click the up or down arrow to increase or decrease the entry in the text box, or enter the value (0~255) directly from the keyboard. After adjusting the threshold value, you can save the setting to a file under a file name and load the file again whenever you want to use the setting. To restore the threshold setting to its default value, click this button. Click the [OK] button. The preview image will change to reflect the new settings. 50

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50
S T E P
3
Adjusting the Threshold Value
When the scan mode is set to black and white, the image brightness can be
adjusted. The threshold value setting determines whether a halftone will be
expressed as a black or a white data point. The possible threshold values range
between 0 and 255. Below a given threshold value, all data is converted to black.
Likewise, all data with a value above the threshold is converted to white.
Accordingly, higher threshold values produce darker images while lower threshold
values result in brighter images.
To Set the Threshold Value
When the scan mode is set to black and white, click the [Tone
Adjustment] button or pull down the Image menu and select [Tone
Adjustment].
Threshold Value = 128 (Standard)
Threshold Value = 70
Threshold Value = 180
Click the [OK] button.
The preview image will change to reflect the new settings.
Drag the slidebar left or right to adjust the
threshold setting.
After adjusting the threshold value, you can
save the setting to a file under a file name and
load the file again whenever you want to use
the setting.
Click the up or down arrow to increase or
decrease the entry in the text box, or enter the
value (0~255) directly from the keyboard.
To restore the threshold setting to its default value, click this button.