ISCTL       (device, quality)

   APL code               182
   GDDM RCP code          X'0C300002' (204472322)

device (specified by user) (fullword integer)
The image to which the call applies. Possible values are:

-1

Scanner

0

Current page.

quality (specified by user) (fullword integer)
The limit(s) of approximation allowed for transforms.

0

Default, the same as 3.

n

A number in the range 1 through 5, that has this meaning:

      n     pae        sfm         hsa     eor     air

      1     d/c        any         d/c     d/c     d/c
      2     d/c     0.4 - 2.50     d/c     d/c     d/c
      3     yes     0.8 - 1.25     d/c     d/c     d/c
      4     yes     0.9 - 1.11     yes     yes     yes
      5     yes     1.0 - 1.00     yes     yes     yes

Note: In the above table,

d/c

means "don't care"

pae

means "process all extractions"

sfm

means "scale factor multiplier"

hsa

means "honor scaling algorithm"

eor

means "emulate overlapped rectangles"

air

means "avoid image-size rounding."

For information on the effects of these values on the different transfer elements, see the Description section below.

Extractions

"Don't care" means that only the number of extractions (transforms) supported by the device need be processed. A warning message is issued on the IMXFER or IMAPT call if one or more extractions is ignored.

The 3193 can perform four extractions.

"Yes" means that all extractions must be processed, with extra processing in GDDM if there are more than the device can process.

Scaling factor

The scale factors can be modified by a multiplier within the range shown in the table above. For example, if a device has scale factors of (1/4, 1/3, 1/2, 2/3, 3/4, 1, 4/3, 3/2, 2, 3, 4) then the (default) multiplier range of 0.8 through 1.25 allows any scale factor in the range 0.2 through 5.0 to be approximated. An information message is issued on the IMXFER, IMAGTx, or IMAPTx calls if approximation occurs.

If the scale factor cannot be approximated, GDDM emulates the function.

Scaling algorithm

"Don't care" means that a device algorithm can be used, even if this is not the same as that requested by the transforms. An information message is issued on the IMXFER or IMAPT call if a different algorithm is used.

"Yes" means that the requested algorithm must be used, with emulation in GDDM if it is not supported by the device.

Overlapped target rectangles

When target rectangles overlap, some devices do not always give correct results in the overlapped parts. This is because the processing of rectangles (possibly in parallel) may be determined by the order the source rectangles occur in the sequential image data, rather than the order the rectangles are specified in the projection; that is, the incorrect result is caused by mixing the (correct) pixels in a different order. Even when overlap occurs, correct results are obtained for those pixels mixed with "symmetric" mix modes, that is, if the logical expression for the result is commutative and associative.

"Unexpected" target rectangle overlap can occur if scale factors or resolutions are modified by approximation (see above).

"Don't care" means that overlapped target rectangles may be processed by the device. An information message is issued on the IMXFER or IMAPT call if overlap can cause incorrect results.

"Yes" means that all extractions must be processed as if they were sequentially in the correct order, with emulation in GDDM if overlap could cause incorrect results.

Image-size rounding

The scanner can only scan an area of the paper that is a multiple of 8 pixels wide. Also, the left edge of the scanned area must be a multiple of 8 pixels from the left edge of the scanner detector.

When the "avoid image-size rounding" quality value is "don't care," GDDM may round the scanner image size, and the extract sizes (specified in a projection) to suit the scanner limitations. It is best to use the "don't care" value if direct transmission from the scanner is required.

When the "avoid image-size rounding" quality value is "yes," GDDM processes the scanned images to ensure that the effects of the rounding are not noticeable by the application or the user.

ADM3386 E

CALL NOT ALLOWED DURING GET/PUT SEQUENCE

ADM3455 E

DEVICE n IS INVALID

ADM3456 E

QUALITY n IS INVALID