Marblecore Imaging Library Documentation

Documentation / Marblecore Imaging / Methods / AdjustContrast

AdjustContrast method

Syntax

Boolean AdjustContrast(nPercentage As Number, nChannel As Channel, nLeft As Number, nTop As Number, nWidth As Number, nHeight As Number)

Return value

Returns true if the function succeeded.

Parameters

Parameter	Type	Required	Description
nPercentage	Number	Yes	The amount of the adjustment ranging from -100%...100%. A value of 0 means no change, less than 0 will decrease the contrast and greater than 0 will increase the contrast of the image.
nChannel	Channel (Enumeration)	No	Optional parameter which specifies the color channel to adjust.
nLeft	Number	No	Optional parameter which can be used to specify a clipping rectangle. This parameter specifies the left coordinate of the rectangle.
nTop	Number	No	Optional parameter which can be used to specify a clipping rectangle. This parameter specifies the top coordinate of the rectangle.
nWidth	Number	No	Optional parameter which can be used to specify a clipping rectangle. This parameter specifies the width of the rectangle.
nHeight	Number	No	Optional parameter which can be used to specify a clipping rectangle. This parameter specifies the height of the rectangle.

Example

The example below shows the effect of this method and how to use it. You can slide the marker in the before/after picture to see the difference. If you take a look at the example code, assume there is a reference to the Marblecore Imaging object with the name 'MarblecoreImaging'. Transparent parts of the image are displayed using a checkerboard pattern.

1 // Load the specified image in memory
2 MarblecoreImaging.LoadFromFile("example-adjustcontrast-before.jpg");
3 
4 // Execute the operation
5 MarblecoreImaging.AdjustContrast(50);
6 
7 // Save the modified image to the specified file
8 MarblecoreImaging.SaveToFile("example-adjustcontrast-after.jpg");

Category

Color adjustments

See also

AdjustBrightness | AdjustColorBalance | AdjustColorLevel | AdjustGamma | AdjustHue | AdjustHueSaturation | AdjustLightness | AdjustRGB | AdjustSaturation