sgi2ps(1)
sgi2ps - convert an SGI image file to PostScript
As shipped in IRIX 6.5. First release of IRIX 6.5.
NAME sgi2ps - convert an SGI image file to PostScript SYNOPSIS sgi2ps [-O filename] [-L filename] [-B] [-C colorspace] [-F] [-f] [-r angle] [-p imageRes] [-z factor] [-n nCopies] [-G g0[,g1,g2]] [-N nUpX[,nUpY]] [-I filename] [-c filename] [-h] [-D] [SGIImageFilename ...] DESCRIPTION sgi2ps converts raster files in SGI image format into PostScript code. The program provides a number of image transformation capabilities including zooming, rotation and gamma correction. In addition, sgi2ps provides the capability to display multiple images on a single physical page. Command Line Options Typically, sgi2ps expects at least one SGI image file to be specified as input on the command line after all option switches. If no image file is specified on the command line, sgi2ps will read from the standard input. By default, sgi2ps assumes that its output should be written to the standard output and messages should be written to standard error. -O filename Specifies the name of the file to which the PostScript output will be sent. If the -O option is not specified, output will be sent to the standard output. -L filename Specifies the name of the file to which error, warning and informational messages are to be written. If the file specified already exists, any messages generated by sgi2ps will be appended to the end of the file. If the -L option is not specified, message output will be sent to standard error. -B Specifies that binary PostScript should be output where applicable. The majority of the output from sgi2ps is bitmap image data. By default this data is output as ASCII hexadecimal values. Specifying -B will output this image data as binary values thereby cutting in half the number of bytes of PostScript data output. However, binary data output should only be used when the communications channel between sgi2ps and the PostScript interpreter can accept 8-bit data. This precludes the use of the -B switch when transmitting output over serial connections. -C colorspace Specifies the output data colorspace. The value of colorspace may be one of the following: w (black and white), the default, cmyk, or rgb. The PostScript produced by cmyk and rgb can only be interpreted by a Level 2 PostScript interpreter or a Level 1 interpreter with the CMYK color extensions (e.g. psrip(1)). The PostScript produced by w can be sent to any Level 1 interpreter. The colorspace conversion equations used by sgi2ps are: W to RGB: r = g = b = w W to CMYK: c = m = y = 0; k = 1 - w RGB to W: w = 0.299 r + 0.587 g + 0.114 b RGB to CMYK: ci = 1 - r; mi = 1 - g; yi = 1 - b k = min(ci, mi, yi) c = ci - k; m = mi - k: y = yi - k -F Specifies that the image should be oriented so that it best fits the page. That is, the image is oriented such that its longer dimension is parallel with the longer dimension of the paper. If -F is specified, any rotation specified by the -r switch is ignored. By default the image is oriented with zero degrees of rotation unless the -r switch specifies a different rotation. -f Specifies that the output image should be flipped (mirrored) about the vertical axis. This flag is useful when creating transparencies. Note that flipping of the image is performed after any rotation. Therefore, the image is always flipped about the vertical axis. -r angle Specifies that the image is to be rotated by angle degrees. angle may be any positive or negative integer value. Positive rotations are counter-clockwise measured from the horizontal axis. The default rotation angle is 0. Note that rotation is performed before any image flipping (-f). The -r switch is ignored if the best-fit switch -F is specified. -z factor and -p imageRes Each of these switches provides scaling of the original image. The two switches are mutually exclusive. The -z switch provides image zooming. factor is a positive floating point value typically between 0.0 and 1.0. A zoom factor of 1.0, the default, indicates that the image should be scaled to fit the entire page while preserving the original image's aspect ratio. A zoom factor of 0.5 would produce an image sized to 50% of that needed to fit the entire page. A zoom factor of 0.0 produces no zooming. Instead the image is output at its original size. If an image must be sized based on a given resolution, the -p switch should be specified in place of the -z switch. The imageRes argument specifies the resolution used to size the image in dots per inch. This resolution is independent of the output device resolution. For example, suppose an image is one inch by one inch when displayed on a 96 dpi monitor. In order to print that image on a 300 dpi printer so that it remains one inch by one inch the -p switch would be specified with an imageRes of 96. -n nCopies Specifies the number of copies to produce of each page. Specifying this switch simply sets the value of the #copies variable in the output PostScript code. The value of this variable is used by the PostScript operator showpage to determine the number of output copies to produce. By default the #copies variable is not specified and the number of copies then defaults to one. -G g0[,g1,g2] This switch provides gamma correction of the input image data. The gamma function is: corrected value = value ^ gamma The gamma value (g0, etc.) is typically a value between 0.0 and 3.0. A gamma value less than 1.0 will tend to lighten the image while a value greater than 1.0 will tend to darken the image. A gamma of 1.0 will leave the image data unchanged. The gamma value may be specified for each input color channel individually or as a group. If g0 is the only gamma value specified, this value will be applied to all output channels. Note that a black and white image contains one input color channel, and an RGB image contains three input channels. The default gamma value is 1.0 for all channels. -N nUpX[,nUpY] sgi2ps allows multiple SGI image files to be specified on the command line. By default, each image is output on a separate physical page. The -N switch provides the capability to divide up one physical page into multiple virtual pages. This is often called n-up display. Using n-up, multiple image files can be displayed on the same physical page. If only the nUpX value is specified the physical page will be divided into nUpX by nUpX virtual pages. If both nUpX and nUpY are specified, the physical page will be divided into nUpX by nUpY virtual pages. Images are displayed in row (horizontal) major order. Note that nUpX is measured along the horizontal, x, axis. For an 8.5 by 11.0 inch page, the horizontal axis is the short dimension in portrait mode and the long dimension in landscape mode. Rotation is performed on each image individually and best-fit orientation is determined for each image individually. Zooming is relative to the virtual page size. Note that image replication is not performed. The number of images specified on the command line is the number of images displayed in the virtual pages. -I filename sgi2ps places a PostScript code prolog at the start of the output file. By default, this prolog code is read from the file /usr/lib/print/data/PSImageProlog. The -I switch allows a different prolog file to be specified. This switch is not intended for general use. -c filename The most common form of SGI Image file is the so called Normal image. This image contains the actual intensity values for each image channel at each pixel location. Another form of SGI Image file is the so called Screen image. This image consists of a single value at each pixel. The value is an index into a colormap that contains the actual pixel intensity values for each channel. This type of image is also referred to as a colormap image. In order to process a colormap image, the colormap that corresponds to the image must be specified. By default sgi2ps obtains its colormap from the file SGIDefColormap.map. This file contains the default SGI system colormap. The -c option can be used to specify a different colormap file. A colormap file can be created using the makemap(1G) and savemap(1G) programs. This switch is not intended for general use. -h Prints a program usage message to the standard error. This usage message also lists the currently supported output configurations. -D Specifies verbose output for debugging purposes. NOTES 1. The PostScript output produced by sgi2ps conforms to the Adobe PostScript Document Structuring Conventions Version 3.0 as specified in Appendix G of the "PostScript Language Reference Manual", 2nd edition. 2. The sgi2ps program supersedes the rgb2ps program. The rgb2ps program should not be used for new development and may be removed from future releases. 3. The PostScript output produced by sgi2ps primarily wraps the input bitmap image data with PostScript instructions. Therefore, the amount of output data can be quit large especially if multiple image files are specified or if the images are large. The size of the output file should be kept in mind when sending the PostScript output over a slow communications channel such as a serial line. 4. If sgi2ps is given an unrecognized or incomplete command line option switch, it will print a warning message to the standard error, ignore the option and continue processing. 5. If an image file is specified on the command line, sgi2ps will not read its stdin for images. 6. Processing an SGI Image format file requires random seeking within the file. Therefore, when sgi2ps is obtaining its input image from a pipe to standard input, a disk based copy of the input image must be created. This temporary image file will be created in the directory specified by the TMPDIR environment variable. If that variable is not set, the temporary file will be created in /var/tmp. There must be sufficient free space in the temporary file directory to store a complete copy of the image file or sgi2ps will fail. 7. sgi2ps can only process a single image file when reading from standard input. 8. Previous versions of sgi2ps performed gamma correction on the output data. Starting with Impressario 1.2, sgi2ps performs gamma correction on the input image data. 9. sgi2ps can process Normal and Screen format SGI Image files. Images in the obsolete Dither format must be converted to Normal format images using the fromdi(6D) program. FILES /usr/lib/print/sgi2ps Program file /usr/lib/print/data/PSImageProlog PostScript prolog file /usr/lib/print/data/SGIDefColormap.map Default colormap file TRADEMARKS PostScript is a registered trademark of Adobe Systems, Inc. SEE ALSO psrip(1), stiff2ps(1), PostScript Language Reference Manual - 2nd ed., Adobe Systems, Inc., makemap(1G), savemap(1G), fromdi(6D)