Introduction
PostScript printer
:::: TYPES OF POSTSCRIPT
:::: CONVERTING POSTSCRIPT FILES
:::: CHANGING THE LAYOUT OF POSTSCRIPT FILES
:::: SPLITTING POSTSCRIPT FILES
:::: OTHER CHANGES TO POSTSCRIPT FILES
:::: CHANGING APPEARANCE
:::: CONVERTING IMAGES TO POSTSCRIPT
PaintJet printer
LaserJet printer
Windows .BMP files
GIF Files for World Wide Web and Other Applications
DigImage Raw Files
DigImage Compressed Files
Saving images for later conversion by DigiFile
Index
Images may be rendered as a grey scale on an HP LaserJet III or later printer or compatible printer. The rendering process uses an error diffusion algorithm to produce the required grey levels from the intensities. This algorithm is similar to that used by the PaintJet XL, XL300 and DeskJet 1200C when the /R E error diffusion option is chosen. For the LaserJet the command takes the form
C:..> DIGIFILE image_file /FL [output_file] [/NF] [/O output_lut]
[/X width] [/Y height] [/M margin]
[/W iw0 iw1 jw0 jw1] [/G gamma] [/T title]
[/D [buffer]] [/PT tray]
The /FL
switch is used to indicate that the image file is being converted
for printing on a HP LaserJet series laser printer or DeskJet
series ink jet printer. If the optional output_file
is not given, then the output will be written to the printer connected
to the port specified in the DigImage configuration file. If output_file
is specified, then the output will be written to the file indicated.
This file may subsequently be printed using COPY
/B output_file LPT1 (or whichever other
port is required). Note that the switches may be present in any
order. The other (optional) switches have the following effects:
| Switch | Effect |
| /NF | If present, this switch suppresses the form feed which will normally be issued at the end of the plot. This will then enable a second or third image to be dumped onto the same page. |
| /O output_lut | If not present, then the intensities will be used directly to determine the grey level in the LaserJet image. If included, the intensities will be used to determine the red, green and blue components of the false colour associated with each pixel. These components will then be combined to give a grey level determined from 0.30red + 0.59green + 0.11blue. This gives an equivalent intensity for a colour image, enabling nominally full coloured images to be rendered appropriately in the grey-scale LaserJet image. |
| /X width | If present, this switch specifies the width of the plot in mm. If this switch is not present but /Y is, then the width will be chosen automatically to maintain the aspect ratio. If neither /X or /Y are present, then the default will depend on how the image was saved. If the image was saved by [;DP Dump the screen to PaintJet printer file], then the width will be whatever was specified at that time. If the image were saved using the [;K: Save and restore buffer] menu, then the default width is 180 mm. |
| /Y height | If present, this switch specifies the height of the plot in mm. If this switch is not present but /X is, then the height will be chosen automatically to maintain the aspect ratio. If neither /X or /Y are present, then the default width is selected in the manner outlined for /X above and the height selected to maintain the aspect ratio. |
| /M margin | If present, this switch sets the left-hand margin, in mm, for the plot. If not present, then the default will depend on how the image was saved. If the image was saved by [;DP Dump the screen to PaintJet printer file], then the left margin will be whatever was specified at that time. If the image were saved using the [;K: Save and restore buffer] menu, then the margin is set to 200mm-width. |
| /W iw0 iw1 jw0 jw1 | This switch may be used to reduce the size of the window to be dumped to the printer. If not present, then the entire window contained in the file will be used. If the image file itself were saved as a window, then the top left corner of the image is loaded to coordinates 0,0 (not the original position of the window) and so the new sub-window coordinates should be relative to this. |
| /G gamma | Specifies gamma correction to characterise nonlinearity between apparent colour/intensity and true colour/intensity. Default value (if /G not specified) is 1.5, or that specified by [;DP Dump the screen to PaintJet printer file] if the image were saved using this option.. |
| /T title | Specify title for plot. The text included after the /T switch up until the end of the line or the next / character is printed out above the screen dump. If the image were saved using [;DP Dump the screen to PaintJet printer file], then the title specified at this point will be used as the default. The default for [;K: Save and restore buffer] is no title. |
| /D [buffer] | If the /D switch is included by itself, then the image, once loaded, will be displayed on the computer monitor. If buffer is also included, then the image will be displayed on the frame grabber monitor using the specified buffer number. Note that this last option is the only one for which DigiFile requires the frame grabber card to be installed. |
| /PT tray | If included, then this switch will select a specific source for the paper. Valid values of tray are:0 Manual feed
1 Default tray |
If you have the option of printing on a LaserJet or a PostScript compatible printer, then which is better will depend both on the resolution of the printer and the type of images being printed. For the same printer resolution, an image rendered using the LaserJet option will be produced faster and often appear better than one rendered using PostScript. The reason for this lies in the different methods of producing an apparent grey level. With PostScript, each pixel is represented as accurately as possible for that pixel. In contrast, with the LaserJet, DigImage tries to represent the grey level in the region around the pixel accurately. While the same form of error diffusion (also known as frequency modulation) algorithm could be implemented in PostScript, the much larger file size and slower printing make this less useful. Note that some implementations of PostScript will use such an algorithm by default even though it represents a departure from standard PostScript.
Many modern PostScript printers offer the ability to switch automatically
between PostScript and PCL5. On such printers you can send either
type of image without any further effort.
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