Digital

NAME

XieDither − This routine creates a dithered copy of a source image. 

C Format

dst_photo_id = XieDither(src_id, levels)

C Argument Information

XiePhoto     dst_photo_id;
XiePhoto     src_id;
unsigned long  ∗levels;

RETURN VALUES

If the source image is an unbound photomap, the routine returns the identifier of the newly created image in the dst_photo_id argument. Otherwise, the routine returns the identifier of the photoflo to which the processing element is appended. You can free the photomap using the XieFreeResource routine. 

PARAMETERS

src_idThe src_id argument specifies the source image.  If the source image is an unbound photomap, the operation is performed immediately. Otherwise, the processing element is appended to the specified photoflo with execution pending a call to the XieExecuteFlo routine. The photoflo is specified explicitly if the source image is a photoflo, or implicitly if the source image is a photomap or phototap bound to the photoflo. 

levelsThe levels argument specifies the address of an array containing the maximum number of output levels for each component of the dithered image. For example, to dither a gray scale image down to a bitonal image, the array entry would be levels[0] = 2; and to dither a multispectral image to 8 bits per pixel the array entries can be levels[0]=3, levels[1]=3, and levels[3]=2.  If you specify a null value, the routine uses a default of 2 levels per component. Dithering to 1 level results in a value of 0 for all pixels in the component. 

DESCRIPTION

This routine creates a dithered copy of a source image. 

If the operation is performed immediately and you selected computation events using the XieSelectEvents routine, an XieK_ComputationEvent is added to the X11 event queue when the routine is completed. 

XIE Events and Error Messages

Protocol Messages: X_ieDither

XIE event returned: XieK_ComputationEvent if immediate execution and computation events are selected

XieLib errors: None

XieServer errors: BadIDChoice -- Invalid identifier

BadAlloc -- Insufficient server resources

BadMatch -- The source image is not constrained or the levels argument is greater than the levels in the source image

BadValue -- The levels argument is 0 or negative