src/tiff/man/TIFFReadRGBAStrip.3tiff

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