2005.10.26 12:06 "Re: [Tiff] Re: checking test images", by ryuki_dono

>
>> I didn't know that libtiff was so limited. Or did I something wrong?
>> I think quad-jpeg and zackthecat can't
>> be decoded because of my missing JPEG support in my build. But whats
>> with all the 2 to 64 Bit pixeldepth?
>> What's with the contig files?
>

It was not meant as an insult. I used JPEG.lib and PNG.lib before and they where able to provide the full support of the image format with high level functions. I had to check the support informations more. I only wondered why there is no 24 and 32 bit support yet? Since TIFFReadRGBAImage provides 4x8Bit output there should be no problem with that.

But I don't feel comfortable hacking the support into the library functions.

Only for providing a simple solution:

static void MyRobWarningHandler(const char* module, const char* fmt, va_list ap)

{
    return;
}

static void MyRobErrorHandler(const char* module, const char* fmt,
va_list ap)
{
    throw "Error";
    // CString message;
   // throw message.Format(fmt,ap);
}

bool CDIB::Load_TIF(CString &pf) // Load from file (ORIGINAL) TIF
{

    TIFF* tif=NULL;
    uint32* raster=NULL;

    uint32 w, h; // width and height
    size_t npixels;

    uint16 orientation=ORIENTATION_TOPLEFT;

    try {

tif = TIFFOpen((LPCTSTR)pf, "r");
    if (tif)
    {

    TIFFSetErrorHandler(MyRobErrorHandler);    // break when errors occure
    TIFFSetWarningHandler(MyRobWarningHandler); // ignores warnings

TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, &w);
  TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &h);

    TIFFGetField(tif, TIFFTAG_ORIENTATION, &orientation);

    npixels = w * h;
    raster = (uint32*) _TIFFmalloc(npixels * sizeof (uint32));

    if (raster != NULL)
    {

        if (TIFFReadRGBAImage(tif, w, h, raster, 0)) // try to read RGBA
data
        {
            if (!Create(w, h, 24)) // malloc dib memory for 24 bit
data everytime
            {
                _TIFFfree(raster); // free all memory

TIFFClose(tif);

                return false; // error
            }
            BYTE *bits;
            BYTE *source=(BYTE*)raster;
            for (long y=0; y < h; y++)
            {
                if ((orientation==ORIENTATION_TOPLEFT) ||

(orientation==ORIENTATION_TOPRIGHT)) // upside down picture

                    bits=(BYTE*)GetPixelAddress(0,h-y-1);    // get 

memory adress of pixel

                else
                    bits=(BYTE*)GetPixelAddress(0,y);
                for (long x=0; x < w; x++)
                {

                    *bits++ = (BYTE)source[2];    //B copy ABGR -> BGR
                    *bits++ = (BYTE)source[1];    //G
                    *bits++ = (BYTE)source[0];    //R
                    source+=4;    // count 4 bytes further

                } // endfor x
            } // endfor y
        } // endif raster

        _TIFFfree(raster);
    }

TIFFClose(tif);

    }

    else // no tif
        return false;
    } catch (char *message) // error
   {
        if (raster) // you can try to read the image after all
        {
            _TIFFfree(raster); // free memory
        }
        if (tif) TIFFClose(tif); // close tiff
       return false;
   }
  return true; // no error while reading the image
}

As you can see I corrected the RGB copy part. Now that litle function should read all standart tiff images. If there is an error while reading, the function doesn't provide an image but the return value false. That small function would have saved me a lot of time, since I wasn't able to find any sample about using an own errormanagement. I hope it helps some beginners.

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