IMRCVB

GDDM V3R2 Base Application Programming Reference

IMRCVB

GDDM V3R2 Base Application Programming Reference
SC33-0868-02

Function

To define bi-level conversion algorithm.


   IMRCVB      (proj-id, alg, count, alg-data)

   APL code               1664
   GDDM RCP code          X'3C030201' (1006830081)

Parameters

proj-id (specified by user) (fullword integer)
A projection with an incomplete transform, to which this transform element is to be added.

alg (specified by user) (fullword integer)
The algorithm to be used for conversion to bi-level. Possible values are:

0

The default algorithm; this is device-dependent. For image scanners this is the same as 1.

Note: When writing device-independent code, it is recommended that a count parameter of zero is used when specifying the default algorithm.

1

Threshold.
A threshold is defined for comparison with each source pixel. Pixels above the threshold specified by alg-data(1) become white and below it become black.

alg-data(1) specifies the required threshold in the range 0.0 through 1.0 where 0.0 is black and 1.0 is white. The default threshold is 0.5.

The image scanners provide three threshold levels, the level used depends on the value of alg-data(1) as follows:

0.0 through 0.25

Dark original

>0.25 through <0.75

Normal original

0.75 through 1.0

Light original.

10

Halftoning type A
This is best for intricate pictures.

The alg-data array is not used.

11

Halftoning type B
This is best for images in which the gray levels vary gradually.

The alg-data array is not used.

12

Compressed data stream
This is best for pure gray-scale documents such as photographs.

The alg-data array is not used.

count (specified by user) (fullword integer)
The number of parameters defined in the alg-data array.

alg-data (specified by user) (array of short floating-point numbers)
An array of numbers that are the data required by the specified algorithm. For information, see the alg parameter description.

Description

Defines the algorithm to be used during conversion to bi-level in a sub-image. "Thresholding" or "halftoning" are the two types of conversion allowed.

The result of this call is a bi-level sub-image, and so any subsequent gray-scale transform element calls have no effect.

The IMRCVB call has no effect if the sub-image is bi-level.

Only one IMRCVB call is allowed for a given transform; subsequent IMRCVB calls are an error.

Principal errors

ADM3401 E: INVALID PROJECTION IDENTIFIER
ADM3402 E: PROJECTION DOES NOT EXIST
ADM3404 E: TRANSFORM ALREADY CONTAINS A CALL TO THIS ROUTINE
ADM3413 E: INVALID ALGORITHM
ADM3414 E: INVALID COUNT
ADM3415 E: INVALID ALGORITHM DATA VALUE

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