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TIFF and LibTiff Mail List Archive

Thread

2003.09.30 14:38 "[Tiff] how can i show the different TIFF tile image on the computer screen?", by Zuyuan Wang
2003.09.30 15:27 "[Tiff] how can i show the different TIFF tile image on the computer screen?", by Kai-Uwe Behrmann
2003.09.30 17:21 "[Tiff] how can i show the different TIFF tile image on the computer screen?", by Andrey Kiselev
2003.10.31 00:45 "ask for suggestions....", by
2003.10.31 00:51 "Re: ask for suggestions....", by
2003.10.31 10:41 "[Tiff] Re: ask for suggestions....", by Zuyuan Wang
2003.10.31 11:35 "[Tiff] Re: ask for suggestions....", by Andrey Kiselev
2003.11.03 15:23 "[Tiff] Re: ask for suggestions....", by Zuyuan Wang
2003.11.03 16:14 "[Tiff] Re: ask for suggestions....", by Andrey Kiselev
2003.11.04 09:52 "[Tiff] Re: ask for suggestions....", by Zuyuan Wang
2003.12.26 11:37 "Re: [Tiff] Reading and writing out TIFFTAG_CLIPPATH", by Andrey Kiselev
2003.12.26 23:29 "Re: [Tiff] Reading and writing out TIFFTAG_CLIPPATH", by Jae Ho Lee
2003.12.28 21:43 "Re: [Tiff] Reading and writing out TIFFTAG_CLIPPATH", by Andrey Kiselev
2003.10.31 16:40 "[Tiff] Re: ask for suggestions....", by
2003.10.31 16:45 "[Tiff] Re: ask for suggestions....", by
2003.11.03 15:36 "[Tiff] Re: ask for suggestions....", by Zuyuan Wang
2003.11.03 16:01 "[Tiff] Re: ask for suggestions....", by Frank Warmerdam
2003.11.03 16:58 "[Tiff] Re: ask for suggestions....", by Andrey Kiselev

2003.11.03 16:01 "[Tiff] Re: ask for suggestions....", by Frank Warmerdam

Dear Frank,

> Would you please attatch the TIFFReadRGBATile() manual pages as a
> document? There are a lot of wrong words of the mail you sent to me. I
> think that something wong....

Zuyuan,

Sorry... it was still formatted for terminal window output. I have
reformatted and attached a more readable version.

> Would you like tell me what's the difference between TIFFReadTile and
> TIFFReadRGBATile? I tried them both, but neither works. If I used the
> TIFFReadTile for reading the tile image, then is is right that the
> buffer size should be (tilewidth* tileLength *3)*uint32? I have noticed
> that TIFFGetR, TIFFGetG, and TIFFGetB is used in the condition of
> TIFFReadRGBATile, then can I use TIFFGetR, TIFFGetG, and TIFFGetB to
> read the data out read by TIFFReadTile?

TIFFReadTile() reads the raw data, while TIFFReadRGBATile() interpretes
various information about color modes, sample size and tries to produce
a normalized RGBA output image suitable for viewing.

They both work. You just haven't gotten a handle on how to work with them.

You cannot use TIFFGetR() and similar macros with the output of TIFFReadTile().
You have to interprete data from it in terms of the other tag information.
If you just want a picture you can do something with you are likeliy better
off using TIFFReadRGBATile().

I would stress the need to review all available reference material. I am
not personally keen on talking you through the more esoteric issues of
imagery programming in C.

> Waiting for your kind suggestions....
> Best regards....
> Zuyuan

-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

TIFFReadRGBATile(3T) TIFFReadRGBATile(3T)

NAME
        TIFFReadRGBATile - read and decode an image tile 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 TIFFReadRGBATile(TIFF* tif, uint32 x, uint32 y, uint32 * raster )

DESCRIPTION
        TIFFReadRGBATile reads a single tile of a tile-based image into memory,
        storing the result in the user supplied RGBA raster. The raster is
        assumed to be an array of width times length 32-bit entries, where
        width is the width of a tile (TIFFTAG_TILEWIDTH) and length is the

        height of a tile (TIFFTAG_TILELENGTH).

The x and y values are the offsets from the top left corner to the top left corner of the tile to be read. They must be an exact multiple of the tile width and length.

Note that the raster is assume to be organized such that the pixel at location (x,y) is raster[y*width+x]; with the raster origin in the lower-left hand corner of the tile. That is bottom to top organization.

        Edge  tiles  which  partly  fall  off the image will be filled out with

        appropriate zeroed areas.

        Raster pixels are

        macros  TIFFGetR,  TIFFGetG,  TIFFGetB,  and TIFFGetA should be used to

        access individual

        See  the  TIFFRGBAImage(3T)  page for more details on how various image

        types are converted to RGBA values.

NOTES

        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).

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

TIFFReadRGBATile is just a wrapper around the more general TIFFRGBAIm- age(3T) facilities. It�s main advantage over the similar TIFFReadRG- BAImage() function is that for large images a single buffer capable of holding the whole image doesn�t need to be allocated, only enough for

        one  tile.   The  TIFFReadRGBAStrip() function does a similar operation

        for stripped images.

RETURN VALUES
        1 is returned if the image was successfully read and converted. Other-

        wise, 0 is returned if an error was encountered.

DIAGNOSTICS

All error messages are directed to the TIFFError(3T) 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

        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.

BUGS

Orientations other than bottom-left, or top-left are not handled cor- rectly.

SEE ALSO

        libtiff(3T),  TIFFOpen(3T),  TIFFRGBAImage(3T),  TIFFReadRGBAImage(3T),

TIFFReadRGBAStrip(3T)