src/tiff/man/TIFFReadRGBAStrip.3tiff

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  25 .if n .po 0
  26 .TH TIFFReadRGBAStrip 3TIFF "December 10, 1998" "libtiff"
  27 .SH NAME
  28 TIFFReadRGBAStrip \- read and decode an image strip into a fixed-format raster
  29 .SH SYNOPSIS
  30 .B "#include <tiffio.h>"
  31 .sp
  32 .B "#define TIFFGetR(abgr) ((abgr) & 0xff)"
  33 .br
  34 .B "#define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)"
  35 .br
  36 .B "#define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)"
  37 .br
  38 .B "#define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)"
  39 .sp
  40 .BI "int TIFFReadRGBAStrip(TIFF *" tif ", uint32 " row ", uint32 *" raster ")"
  41 .SH DESCRIPTION
  42 .IR TIFFReadRGBAStrip
  43 reads a single strip of a strip-based image into memory, storing the result in
  44 the user supplied RGBA
  45 .IR raster .
  46 The raster is assumed to be an array of width times rowsperstrip 32-bit
  47 entries, where width is the width of the image (TIFFTAG_IMAGEWIDTH) and
  48 rowsperstrip is the maximum lines in a strip (TIFFTAG_ROWSPERSTRIP).
  49
  50 .PP
  51 The
  52 .IR row
  53 value should be the row of the first row in the strip (strip * rowsperstrip,
  54 zero based).
  55
  56 .PP
  57 Note that the raster is assume to be organized such that the pixel at location
  58 (\fIx\fP,\fIy\fP) is \fIraster\fP[\fIy\fP*\fIwidth\fP+\fIx\fP]; with the
  59 raster origin in the
  60 .I lower-left hand corner
  61 of the strip. That is bottom to top organization.  When reading a partial last
  62 strip in the file the last line of the image will begin at the beginning of
  63 the buffer.
  64
  65 .PP
  66 Raster pixels are 8-bit packed red, green, blue, alpha samples. The macros
  67 .IR TIFFGetR ,
  68 .IR TIFFGetG ,
  69 .IR TIFFGetB ,
  70 and
  71 .I TIFFGetA
  72 should be used to access individual samples. Images without Associated Alpha
  73 matting information have a constant Alpha of 1.0 (255).
  74 .PP
  75 See the
  76 .IR TIFFRGBAImage (3TIFF)
  77 page for more details on how various image types are converted to RGBA values.
  78 .SH NOTES
  79 Samples must be either 1, 2, 4, 8, or 16 bits. Colorimetric samples/pixel must
  80 be either 1, 3, or 4 (i.e.
  81 .I SamplesPerPixel
  82 minus
  83 .IR ExtraSamples ).
  84 .PP
  85 Palette image colormaps that appear to be incorrectly written as 8-bit values
  86 are automatically scaled to 16-bits.
  87 .PP
  88 .I TIFFReadRGBAStrip
  89 is just a wrapper around the more general
  90 .IR TIFFRGBAImage (3TIFF)
  91 facilities.  It's main advantage over the similar
  92 .IR TIFFReadRGBAImage()
  93 function is that for large images a single buffer capable of holding the whole
  94 image doesn't need to be allocated, only enough for one strip.  The
  95 .IR TIFFReadRGBATile()
  96 function does a similar operation for tiled images.
  97 .SH "RETURN VALUES"
  98 1 is returned if the image was successfully read and converted.
  99 Otherwise, 0 is returned if an error was encountered.
 100 .SH DIAGNOSTICS
 101 All error messages are directed to the
 102 .IR TIFFError (3TIFF)
 103 routine.
 104 .PP
 105 .BR "Sorry, can not handle %d-bit pictures" .
 106 The image had
 107 .I BitsPerSample
 108 other than 1, 2, 4, 8, or 16.
 109 .PP
 110 .BR "Sorry, can not handle %d-channel images" .
 111 The image had
 112 .I SamplesPerPixel
 113 other than 1, 3, or 4.
 114 .PP
 115 \fBMissing needed "PhotometricInterpretation" tag\fP.
 116 The image did not have a tag that describes how to display the data.
 117 .PP
 118 \fBNo "PhotometricInterpretation" tag, assuming RGB\fP.
 119 The image was missing a tag that describes how to display it, but because it
 120 has 3 or 4 samples/pixel, it is assumed to be
 121 .SM RGB.
 122 .PP
 123 \fBNo "PhotometricInterpretation" tag, assuming min-is-black\fP. The image was
 124 missing a tag that describes how to display it, but because it has 1
 125 sample/pixel, it is assumed to be a grayscale or bilevel image.
 126 .PP
 127 .BR "No space for photometric conversion table" .
 128 There was insufficient memory for a table used to convert image samples to
 129 8-bit
 130 .SM RGB.
 131 .PP
 132 \fBMissing required "Colormap" tag\fP.
 133 A Palette image did not have a required
 134 .I Colormap
 135 tag.
 136 .PP
 137 .BR "No space for tile buffer" .
 138 There was insufficient memory to allocate an i/o buffer.
 139 .PP
 140 .BR "No space for strip buffer" .
 141 There was insufficient memory to allocate an i/o buffer.
 142 .PP
 143 .BR "Can not handle format" .
 144 The image has a format (combination of
 145 .IR BitsPerSample ,
 146 .IR SamplesPerPixel ,
 147 and
 148 .IR PhotometricInterpretation )
 149 that
 150 .I TIFFReadRGBAImage
 151 can not handle.
 152 .PP
 153 .BR "No space for B&W mapping table" .
 154 There was insufficient memory to allocate a table used to map grayscale data
 155 to
 156 .SM RGB.
 157 .PP
 158 .BR "No space for Palette mapping table" .
 159 There was insufficient memory to allocate a table used to map data to 8-bit
 160 .SM RGB.
 161 .SH "SEE ALSO"
 162 .BR TIFFOpen (3TIFF),
 163 .BR TIFFRGBAImage (3TIFF),
 164 .BR TIFFReadRGBAImage (3TIFF),
 165 .BR TIFFReadRGBATile (3TIFF),
 166 .BR libtiff (3TIFF)
 167 .PP
 168 Libtiff library home page:
 169 .BR http://www.remotesensing.org/libtiff/
 170