1. Color offset
Normally when you want to include a color illustration in something that is going to be published (journal article, blue-and-white, etc) you supply to the publisher a color print or slide. The publisher then sends the color figure to a color separator who makes a set of 4 color separations (halftoned films) and a color proof. These color separations are made by scanning the original, then digitally producing the halftoned film on a film plotter. With this package we can make a tape that mimics the result of the scanning process, making it possible to produce the color separations directly without an intermediate original. Note that you need to make the separations at precisely the final size they will be used in the article.
The Crosfield format tapes produced by this package are sent to Kedie-Orent in Sunnyvale for processing. The cost for separations is a function of size (prices subject to change):
4"x 5" $63.75
5"x 7" $82.50
8"x 10" $101.25
10"x 12" $116.25
These prices are for 4-5 working day turnaround (they are usually faster). Money will guarantee faster results.
Same day service: %250, 1 Day service: %200, 2-3 Day service: %150.
Currently, the procedure is to get a signed purchase requisition sent to Renee Ognibene for the amount you're going to spend. Then call Fran or Virginia at Kedie-Orent (408-734-9005) and ask to have the work picked up. Tell them you are from Xerox. Mention my name. Leave your tape with the receptionist in the upstairs lobby. The finished work will return to the lobby automatically. Alternatively, you can pick-up and deliver it yourself (is sometimes faster). Kedie-Orent is at 744 San Aleso Ave, Sunnyvale, which is right off 101 at Matilda.
If you want to gang a number of small pictures together to save money, you must add your own alignment marks and separation labels. See MarksAndLabels.gargoyle an example.
There are lot's of little "gotchas" in this process that I don't have ironed out yet. So, please feel free to consult with me on any jobs. If you have a problem, I'll have to fix it anyway and it's always faster to do it right the first time.
InterpressToTape
Go read the interface.
For each Interpress master you need to make an IPSpec:
IPSpec: TYPE = REF IPSpecRep;
IPSpecRep:
TYPE =
RECORD[
name: ROPE, --name of the Interpress file
page: NAT,
pixelsPerInch: NAT, --suggested values: 300 for tapes, 72 for proofing
fDim: REAL, sDim: REAL, -- fastDimension (raster) and slowDimension, in inches
surfaceUnitsPerPixel: NAT ← 5, -- controls averaging for ImagerSmooth; 1 for no smoothing (1 sometimes breaks—will fix ImagerSmooth bug soon)
nBands: NAT ← 1, --will image the file nBands times, clipping for each band
colorCorrection: ColorCorrection ← NIL --default this unless you are a wizard
];
This IPSpec can be used to write a tape or an AIS file for proofing. Note that you need to use a lower resolution for proofing as a 300spi file of any significant size will be too big to view with Preview. fDim and sDim set a window on the Interpress master assuming the lower left corner is at (0,0). If you get these wrong, you will clip off part of your picture. You will get better packing on the tape if fDim is the larger dimension.
Writing Tapes
There should be a registered command or tool. However, there is currently an interpreter interface.
Proof your files using InterpressToTape.Preview. This will make a set of RGB AIS files at an (optionally) reduced resolution. If you really want to see the bits in the separation, use WriteAIS. The AIS files for the separations are interpreted as white = full color and black = no color. So, a cyan patch on a white background will look white on a black background (white paper = no ink).
To start, make an IPSpec and a TapeSpec.
← &cmyk ← ProduceTapesImpl.MakeIPSpec[name: "///7.0/coloroffset/cmyk.ip", fOrg: 0, sOrg:0, fDim: 0, sDim:0, surfaceUnitsPerPixel: 3, colorCorrection: NIL, ppi: 300, colorType: rgbInterleaved] --ignores colorType for crosfield format
← &tapeSpec ← InterpressToTape.DefaultTapeSpec[name: "Test", tapeNumber: 102]
Make sure the files will fit on the tape:
← InterpressToTapeImpl.SizeFromIPSpecs[files: LIST[&cmyk]]
Go mount a tape with a write-ring in it on the tape server, then write the tape. Make sure you have a lot of VM left, (adjust the bands parameter if you have problems) and then go do something else for a while. Time is measured in fractions of hours/file (critical path is how long it takes to image the file at 300spi, smoothed). When the dorado looks idle, it is sending rasters to the tape drive. When the CPU meter is pinned, it is imaging.
← InterpressToTape.WriteTape[files: LIST[&cmyk], format: crosfield, tapeSpec: &tapeSpec];
When the command returns, the tape is finished.
2. Optronics
About the Optronics itself
The Optronics supports 6 different aperture sizes measured in microns. The table indicates the pixels/mm (
ppm) and pixels/inch (
ppi) produced by each aperture size (
a size). The optronics has a maximum line length of 250mm (9.85 inches). The table also includes the raster size for the maximum size (
raster) and the number of tape inches required to store that record on a 6250 bpi tape (
tape). This last figure includes the interrecord gap (0.8") and is computed by: 3*(
raster/6250 + 0.8). To get the total tape length for an image, multiply the amount of tape needed per scan line by the number of scan lines in the images. Tapes are 2400' long.
a size 12.5 25 50 100 200 400
ppm 80 40 20 10 5 2.5
ppi 2030 1015 508 254 127 63
raster 20K 10K 5K 2.5K 1.25K 625
tape 12" 7.2" 4.8" 3.6" 3.0" 2.7"
Which aperture to use? The 12.5 aperture exceeds the color film resolution and is difficult to run so it should only be used for high resolution gray-scale images. For 35 mm slides, the Dunn camera is 1024 pixels over 1.375 inches for an effective resolution of 745 ppi so only the two smallest apertures are an improvement. Note, however, that the color control on the Dunn is significantly less precise. Color monitors are typically 43 ppi in low resolution, full color mode (640 pixels/ 15 inches) and 68 ppi in high resolution mode. Different monitor sizes give different resolutions, of course.
Commands for writing Optronics tapes
There are 5 commands registered for writing Optronics tapes. N.B. Optronics tapes are written on the Sun tape drive (currently mounted in Chroma). Mount a tape, with a write ring in it, on the tape drive before issuing commands from your Cedar machine. If you can't dope out the drive, get help. The commands are:
OptronicsfromGrayAIS <filename> <pixels per inch> -- pixels per inch optional, defaults to 254
OptronicsfromGreyAIS <filename> <pixels per inch> -- optional spelling of gray, for pedants
OptronicsfromColorAIS <filename> <pixels per inch> -- gets three files for red, green, blue
OptronicsfromCmdFile <indirect file> -- reads cmds from a file for multiple images per tape
OptronicsCleanUp -- Closes files and releases tape drive after commands are aborted
If you get something wrong, recovery is less than graceful. The command "OptronicsCleanUp" is always recommended after an abnormal termination.
The following is an example indirect command file for putting 5 AIS images (3 for the color file) on a single tape:
OptronicsfromGreyAIS []<>Users>crow.pa>3d>Fig1.ais 254
OptronicsfromGrayAIS []<>Users>crow.pa>3d>Fig2.ais 254
OptronicsfromColorAIS []<>Users>crow.pa>3d>TexturedBall 254
Optronics tapes are written as follows:
- tape header: "Written by <user name> at <time stamp>"
- filemark
- for each image thereafter:
- header : "<file name>"
- filemark
- image: one record per scan line
- filemark
- 3 additional filemarks note the end of the tape