TIFFReadRGBAImage(3t)

NAME

       TIFFReadRGBAImage, TIFFReadRGBAImageOriented - read and decode an image
       into a fixed-format raster

SYNOPSIS

       #include <tiffio.h>

       #define TIFFGetR(abgr) ((abgr) & 0xff)
       #define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)
       #define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)
       #define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)

       int TIFFReadRGBAImage(TIFF *tif, u_long width,  u_long  height,  u_long
       *raster, int stopOnError)
       int  TIFFReadRGBAImageOriented(TIFF  *tif, u_long width, u_long height,
       u_long *raster, int orientation, int stopOnError)

DESCRIPTION

       TIFFReadRGBAImage reads a strip- or tile-based image into memory, stor-
       ing  the  result in the user supplied raster.  The raster is assumed to
       be an array of width times height 32-bit entries, where width  must  be
       less  than  or  equal to the width of the image (height may be any non-
       zero size).  If the raster dimensions are smaller than the  image,  the
       image  data  is  cropped to the raster bounds.  If the raster height is
       greater than that of the image, then the image data are placed  in  the
       lower  part of the raster.  (Note that the raster is assume to be orga-
       nized such that the pixel at location (x,y) is raster[y*width+x];  with
       the raster origin in the lower-left hand corner.)

       TIFFReadRGBAImageOriented  works  like TIFFReadRGBAImage with except of
       that user can specify the raster origin position with  the  orientation
       parameter. Four orientations supported:

       ORIENTATION_TOPLEFT
              origin in top-left corner,

       ORIENTATION_TOPRIGHT
              origin in top-right corner,

       ORIENTATION_BOTLEFT
              origin in bottom-left corner and

       ORIENTATION_BOTRIGHT
              origin in bottom-right corner.

       If  you  choose ORIENTATION_BOTLEFT result will be the same as returned
       by the TIFFReadRGBAImage.

       Raster pixels are 8-bit packed red, green, blue,  alpha  samples.   The
       macros  TIFFGetR,  TIFFGetG,  TIFFGetB,  and TIFFGetA should be used to
       access individual samples.  Images  without  Associated  Alpha  matting
       information have a constant Alpha of 1.0 (255).

       TIFFReadRGBAImage  converts  non-8-bit images by scaling sample values.
       Palette, grayscale, bilevel, CMYK, and YCbCr images  are  converted  to
       RGB  transparently.  Raster pixels are returned uncorrected by any col-
       orimetry information present in the directory.

       The paramater stopOnError specifies how to act if an error  is  encoun-
       tered  while  reading  the  image.  If stopOnError is non-zero, then an
       error will terminate the operation;  otherwise  TIFFReadRGBAImage  will
       continue  processing data until all the possible data in the image have
       been requested.

NOTES

       In C++ the stopOnError parameter defaults to 0.

       Samples must be either 1, 2, 4,  8,  or  16  bits.   Colorimetric  sam-
       ples/pixel  must  be  either  1,  3,  or 4 (i.e.  SamplesPerPixel minus
       ExtraSamples).

       Palettte image colormaps that appear to be incorrectly written as 8-bit
       values are automatically scaled to 16-bits.

       TIFFReadRGBAImage is just a wrapper around the more general TIFFRGBAIm-
       age(3TIFF) facilities.

RETURN VALUES

       1 is returned if the image was successfully read and converted.  Other-
       wise,  0  is  returned  if  an error was encountered and stopOnError is
       zero.

DIAGNOSTICS

       All error messages are directed to the TIFFError(3TIFF) routine.

       Sorry, can not handle %d-bit pictures.   The  image  had  BitsPerSample
       other than 1, 2, 4, 8, or 16.

       Sorry, can not handle %d-channel images.  The image had SamplesPerPixel
       other than 1, 3, or 4.

       Missing needed "PhotometricInterpretation" tag.  The image did not have
       a tag that describes how to display the data.

       No  "PhotometricInterpretation" tag, assuming RGB.  The image was miss-
       ing a tag that describes how to display it, but because it has 3  or  4
       samples/pixel, it is assumed to be RGB.

       No  "PhotometricInterpretation"  tag, assuming min-is-black.  The image
       was missing a tag that describes how to display it, but because it  has
       1 sample/pixel, it is assumed to be a grayscale or bilevel image.

       No space for photometric conversion table.  There was insufficient mem-
       ory for a table used to convert image samples to 8-bit RGB.

       Missing required "Colormap" tag.   A  Palette  image  did  not  have  a
       required Colormap tag.

       No space for tile buffer.  There was insufficient memory to allocate an
       i/o buffer.

       No space for strip buffer.  There was insufficient memory  to  allocate
       an i/o buffer.

       Can not handle format.  The image has a format (combination of BitsPer-
       Sample, SamplesPerPixel, and PhotometricInterpretation) that  TIFFRead-
       RGBAImage can not handle.

       No space for B&W mapping table.  There was insufficient memory to allo-
       cate a table used to map grayscale data to RGB.

       No space for Palette mapping table.  There was insufficient  memory  to
       allocate a table used to map data to 8-bit RGB.

SEE ALSO

       TIFFOpen(3TIFF),  TIFFRGBAImage(3TIFF), TIFFReadRGBAStrip(3TIFF), TIFF-
       ReadRGBATile(3TIFF), libtiff(3TIFF)

       Libtiff library home page: http://www.remotesensing.org/libtiff/

libtiff                        October 29, 2004       TIFFReadRGBAImage(3TIFF)