tiff - display driver for Tagged Image File Format (TIFF) output

DESCRIPTION

Tiff is a PhotoRealistic RenderMan display driver which produces an output file in Tagged Image File Format (TIFF). It can be used to store R, RGB, and RGBA images in 8-, 16-, or floating point 32-bit-per-component resolutions. If a Z channel is specified, it is written to a separate Pixar format Z file. The TIFF file created employs LZW compression; 8, 16, or 32 bits per sample; one, three, or four samples per pixel; and a planar contiguous configuration.

The tiff driver creates a file whose name is specified in the RiDisplay call.

Like most other image file display drivers, the tiff driver must receive image data in raster scan order, one scanline at a time. The display server buffers image data as necessary to reorder it into raster scan order before sending it to the tiff driver.

DEFAULTS

resolution		512 × 384


pixel aspect ratio	no default


TIFF file name		ri.tiff

There are two variants of the tiff driver available, the internal driver and the external driver. The selection of which driver to use is controlled by the configuration file rendermn.ini described in the User's Manual and the rendermn.ini(5) page. Briefly, a configuration entry of the form:

	/display/tiff  internal

will cause the internal driver to be used. The internal driver will use more virtual memory and less disk space than the external driver, and should be faster.

The tiff driver also has special configuration options to control the resolution information written into the output file as well as the compression used for output. These may be set from the RiDisplay parameter list or through the configuration file.

The TIFF compression scheme can be controlled by adding the parameter "compression" to the RiDisplay parameter list. The parameter takes a string value which should be one of "lzw", "packbits", or "none". The default value for the compression scheme may be set by adding the following line

	/display/tiff/compression  compression-scheme

where compression-scheme is is one of the above strings. If no compression scheme is specified, LZW compression is used.

The TIFF resolution unit can be controlled by adding the parameter "resolutionunit" to the RiDisplay parameter list. The parameter takes a string value which should be one of "inches", "centimeters", or "none". The default value for the resolution unit may be set by adding the following line

	/display/tiff/resolutionunitunit

where unit is is one of the above strings. If no units are specified the default is "none".

If the TIFF resolution unit has been defined as above, the TIFF resolution values can be controlled by adding the parameter "resolution" to the RiDisplay parameter list. The parameter takes a value that is an array of two floats specifying the resolution in the x and y directions. The default value for the resolution values may be set by adding the following line

	/display/tiff/resolutionunit  xresolution,yresolution

where xresolution, yresolution are floating-point numbers separated by a single comma. There should be no spaces between the comma and xresolution. If no values are specified, values of 100.0 are used, except in the case where no units are specified, in which case values of 1.0 are used.

The default image size and pixel aspect ratio are set through the configuration file as follows:

	/display/tiff/xres  xresolution
	/display/tiff/yres  yresolution
	/display/tiff/par  pixelaspectratio

ERROR MESSAGES

The following messages can be produced by the tiff display driver. Each message will be preceded by the generic message number D00001.

DspyOpen_tiff: Alpha length != color length

The precision of the alpha component must be the same as the precision of each of the R, G, and B components.

DspyOpen_tiff: color size is not 8, 16, or 32 bits

The precision of the color components must be either 8, 16, or 32 bits. This message probably results from an inappropriate RiQuantize command.

DspyOpen_tiff: Can not allocate space for scanline

The tiff driver was unable to allocate a scanline buffer. This is probably due to running out of swap space. Reducing the x dimension of the image will reduce the size of the scanline buffer.

DspyOpen_tiff: Picture file is already open

Two calls to DspyOpen_tiff were made without an intervening call to DspyClose_tiff. This should never happen and should be treated as a system bug that should be reported to Pixar.

DspyOpen_tiff: Call to TIFFOpen failed

For some reason the call to the TIFF library routine TIFFOpen failed. This error message should be preceded with a message from the TIFF library shedding more light on the failure. The most common failure is an inability to create the desired TIFF output file.

DspySetW_tiff: Not opened properly

A call to DspySetW_tiff was made without a previous call to DspyOpen_tiff. This should never happen and should be treated as a system bug that should be reported to Pixar.

DspySetW_tiff: Bad scanline window

The driver was asked to display a window with bogus limits. This should never happen and should be treated as a system bug that should be reported to Pixar.

DspySetW_tiff: Call to TIFFWriteScanline failed

For some reason the call to the TIFF library routine TIFFWriteScanline failed. This error message should be preceded with a message from the TIFF library shedding more light on the failure.

SEE ALSO

rendermn.ini(5) tiffdiff(1) PhotoRealistic RenderMan User's Manual

BUGS

The tiff driver doesn't handle Z data correctly and it doesn't check that it is being asked to do so.

The tiff driver currently doesn't handle R data (single channel data).