[Indigo]<Imaging>ImagerTemp>Imager>AISFileFormat.mesa!1

AISFileFormat.mesa

Doug Wyatt, February 22, 1986 2:53:48 pm PST

DIRECTORY

Basics USING [bitsPerByte, bytesPerWord];

AISFileFormat: CEDAR DEFINITIONS

~ BEGIN

bitsPerAISWord: NAT ~ 16; -- an AIS "word" is 16 bits

wordsPerAISPage: NAT ~ 1024; -- an AIS "page" is 1024 "words"

bytesPerAISWord: NAT ~ bitsPerAISWord/Basics.bitsPerByte;

bytesPerAISPage: NAT ~ bytesPerAISWord*wordsPerAISPage;

nil: CARDINAL ~ 177777B; -- commonly used for a nil value

passwordValue: CARDINAL ~ LOOPHOLE[-31574];

AttributeHeader: TYPE ~ MACHINE DEPENDENT RECORD[

password(0:0..15): CARDINAL, -- password, must equal passwordValue

length(1:0..15): CARDINAL -- length in 16-bit words of attribute section, including this header

-- length must be a multiple of wordsPerAISPage

];

byteSizeAttributeHeader: NAT ~ SIZE[AttributeHeader]*Basics.bytesPerWord;

PartHeader: TYPE ~ MACHINE DEPENDENT RECORD[

type(0:0..5): PartType, -- type of attribute part

length(0:6..15): [0..1777B] -- length of part in 16-bit words, including this one

];

byteSizePartHeader: NAT ~ SIZE[PartHeader]*Basics.bytesPerWord;

PartType: TYPE ~ MACHINE DEPENDENT {

nil(0), -- no more parts

raster(1), -- RasterPart follows

placement(2), -- PlacementPart follows

photometry(3), -- PhotometryPart follows

comment(4), -- CommentPart follows

(77B)

};

RasterPart: TYPE ~ MACHINE DEPENDENT RECORD[

scanCount(0:0..15): CARDINAL, -- number of scan lines

scanLength(1:0..15): CARDINAL, -- pixels per scan line

scanDirection(2:0..15): ScanDirection, -- scanning directions

samplesPerPixel(3:0..15): CARDINAL, -- number of samples

codingType(4:0..15): CodingType -- method of coding

];

byteSizeRasterPart: NAT ~ SIZE[RasterPart]*Basics.bytesPerWord;

ScanDirection: TYPE ~ CARDINAL;

There may not be universal agreement on the interpretation of this value. The AIS documentation disagrees with (at least some versions of) AISFile.d. Fortunately, the two most commonly used values are unambiguous:

3 => pixels go toward the right of the page, scan lines toward the bottom

0, 8 => pixels go toward the top of the page, scan lines toward the right

CodingType: TYPE ~ MACHINE DEPENDENT {

nil(0), -- undefined

uca(1), -- UCACoding folllows

(177777B)

};

UCACoding: TYPE ~ MACHINE DEPENDENT RECORD[ -- UnCompressedArray

bitsPerSample(0:0..15): CARDINAL, -- number of bits for each sample

wordsPerScanLine(1:0..15): CARDINAL, -- number of 16-bit words per scan line

scanLinesPerBlock(2:0..15): CARDINAL, -- scan lines in each block, nil if no blocks

paddingPerBlock(3:0..15): CARDINAL -- words of padding at end of block, nil if no blocks

-- if there are blocks, wordsPerBlock = wordsPerScanLine*scanLinesPerBlock+paddingPerBlock

];

byteSizeUCACoding: NAT ~ SIZE[UCACoding]*Basics.bytesPerWord;

PlacementPart: TYPE ~ MACHINE DEPENDENT RECORD[

xLeft(0:0..15): INTEGER, -- position of lower left corner

yBottom(1:0..15): INTEGER,

xWidth(2:0..15): INTEGER, -- size of image area on page

yHeight(3:0..15): INTEGER

];

byteSizePlacementPart: NAT ~ SIZE[PlacementPart]*Basics.bytesPerWord;

PhotometryPart: TYPE ~ MACHINE DEPENDENT RECORD[

signal(0:0..15): SignalType ← bw, -- what type of signal is sampled

sense(1:0..15): CARDINAL ← 0, -- larger sample values are lighter if sense=0, else darker

scale(2:0..15): ScaleType ← nil, -- specifies the conversion between physical and sample values

scaleA(3:0..31), scaleB(5:0..31), scaleC(7:0..31): Value ← [0, 0],

spotType(9:0..15): SpotType ← nil, -- spot type

spotWidth(10:0..15): CARDINAL ← nil, -- in units of 100*(width in pixels)

spotLength(11:0..15): CARDINAL ← nil, -- in units of 100*(length in scanlines)

sampleMin(12:0..15): INTEGER ← -1, -- sample range, if known

sampleMax(13:0..15): INTEGER ← -1,

histogramLength(14:0..15): CARDINAL ← 0 -- number of words in histogram, nil if no histogram

];

byteSizePhotometryPart: NAT ~ SIZE[PhotometryPart]*Basics.bytesPerWord;

SignalType: TYPE ~ MACHINE DEPENDENT {

bw(0), -- black and white

red(1), -- red separation

blue(2), -- blue separation

green(3), -- green separation

cyan(4), -- cyan separation

magenta(5), -- magenta separation

yellow(6), -- yellow separation

x(7), -- x signal (CIE)

y(8), -- y signal

RGB(100), -- red, green, blue samples, 3 per pixel

CMY(101), -- cyan, magenta, yellow samples, 3 per pixel

CMYB(102), -- cyan, magenta, yellow, black samples, 4 per pixel

Yxy(103), -- Y, x, y (CIE) samples, 3 per pixel

comments(177776B), -- specified in comments

undefined(177777B) -- undefined

};

ScaleType: TYPE ~ MACHINE DEPENDENT {

nil(0), -- undefined

reflectance(1), -- reflectance or transmittance

density(2), -- optical density

comments(177776B), -- specified in comments

undefined(177777B) -- undefined

};

Value: TYPE ~ MACHINE DEPENDENT RECORD[

sample(0:0..15): INTEGER, -- 1000*(actual reflectance or density)

level(1:0..15): CARDINAL -- corresponding digital sample value

];

SpotType: TYPE ~ MACHINE DEPENDENT {

nil(0), -- undefined

rectangular(1), -- spotWidth by spotLength

circular(2), -- diameter=spotWidth, spotLength is undefined

comments(177776B), -- specified in comments

undefined(177777B) -- undefined

};

histogramScale: INTEGER ~ 32767;

CommentPart: TYPE ~ BCPLStringBody;

byteSizeCommentPart: NAT ~ SIZE[CommentPart]*Basics.bytesPerWord; -- maximum

BCPLStringBody: TYPE ~ PACKED ARRAY[0..256) OF CHAR;

If s is a POINTER TO BCPLStringBody, length is ORD[s[0]], text is s[1..length]

END.