Compression (ImageKit Control/ Scan Property)

This property sets the compression method used when an image is transferred via memory.

[TVIkScanCompression Type]

Unit
     ImageKit

type
     TVIkScanCompression = (vikScanNoCompress, vikScanPackbits, vikScanGroup3_1D, vikScanGroup3_1D_EOL, vikScanGroup3_2D, vikScanGroup4, vikScanJPEG, vikScanLZW, vikScanJBIG, vikScanPNG, vikScanRLE4, vikScanRLE8, vikScanBITFIELDS);

Property Value

vikScanGroup3_1D, vikScanGroup3_1D_EOL, vikScanGroup3_2D, vikScanGroup4 are in FAX[CCITT] format, and vikScanRLE4, vikScanRLE8, vikScanBITFIELDS are in BMP format.

Explanation

The Compression property sets the compression method used when an image is transferred via memory. When scanning with a custom user interface (UiMode = vikScanNONUI), be sure to set appropriate values in the PixelType and the BitDepth properties. For example, Tiff group 3 or 4 compression images must be 1 bit black and white; JPEG compression images must be either 8 bit grayscale or 24 bit color.

For details about the different methods for transferring images, please refer to the TransferMode property. The possible setting values supported by a scan device can be retrieved using the GetCapEnumToFloat method. Depending on the datasource, uncompressed may be the only file transfer compression method available.

Setting this value

This value can be set at runtime.

Retrieving this value

This value can be retrieved at runtime.

Differences between the ImageKit7/8/9

In VCL the constants contain a "v". In ActiveX, the constants are: ikScanNoCompress, ikScanPackbits, ikScanGroup3_1D, ikScanGroup3_1D_EOL, ikScanGroup3_2D, ikScanGroup4, ikScanJPEG, ikScanLZW, ikScanJBIG, ikScanPNG, ikScanRLE4, ikScanRLE8, ikScanBITFIELDS.