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2010.03.05 18:50 "Re: Tiffs", by Larry Gritz
I'll answer your question in a separate email (and CC the OIIO dev list).
No reason to have it on the TIFF list.
-- lg
On Mar 5, 2010, at 8:30 AM, Deborah wrote:
> Hi Larry,
>
> I don't remember if I thanked you for your comments on my problem.
>
> As you adviced me I'm trying to use OpenImageIO.
>
> This is the code I have so far:
>
> #include <imageio.h>
> using namespace OpenImageIO;
> #include <fftw3.h>
>
> int main (int argc, char *argv[])
> {
> ImageInput *Recibida = ImageInput::create (argv[1]);
> ImageInput *Original = ImageInput::create (argv[2]);
>
> ImageSpec specRecibida;
> ImageSpec specOriginal;
>
> Recibida->open (argv[1], specRecibida);
> Original->open (argv[2], specOriginal);
>
> int width = specOriginal.width;
> int height = specOriginal.height;
>
> fftw_complex *imgRecibida = ( fftw_complex*
> )fftw_malloc(sizeof(fftw_complex) * width * height);
> fftw_complex *imgOriginal = ( fftw_complex*
> )fftw_malloc(sizeof(fftw_complex) * width * height);
> fftw_complex *imgResultado = ( fftw_complex*
> )fftw_malloc(sizeof(fftw_complex) * width * height);
>
> fftw_plan fft_imgRecibida = fftw_plan_dft_1d( width * height,
> imgRecibida, imgRecibida, FFTW_FORWARD, FFTW_ESTIMATE );
> fftw_plan fft_imgOriginal = fftw_plan_dft_1d( width * height,
> imgOriginal, imgOriginal, FFTW_FORWARD, FFTW_ESTIMATE );
> fftw_plan ifft_Resultado = fftw_plan_dft_1d( width * height,
> imgResultado, imgResultado, FFTW_BACKWARD, FFTW_ESTIMATE );
>
> unsigned char *pixelsRecibida, *pixelsOriginal;
> Recibida->read_image (TypeDesc::DOUBLE, pixelsRecibida,
> 2*sizeof(double));
> Original->read_image (TypeDesc::DOUBLE, pixelsOriginal,
> 2*sizeof(double));
>
> for(int k = 0 ; k < width * height ; k++ ) {
> imgRecibida[k][0] = pixelsRecibida[k];
> imgRecibida[k][1] = 0.0;
>
> imgOriginal[k][0] = pixelsOriginal[k];
> imgOriginal[k][1] = 0.0;
> }
>
>
> fftw_execute( fft_imgRecibida );
> fftw_execute( fft_imgOriginal );
>
> return 0;
> }
>
> I'm trying to do two autocorrelations, as you can see, of two images. One
> is an image received via Fax and the other one is the original image (the
> one that was sent).
>
> When I read the image with read_image, I want this image to be read into
> imgRecibida (and the other image in imgOriginal). They are pointers to
> typedef double fftw_complex[2];
>
> I don't understand what is the x stride, or why in your example you said
> 2*sizeof(double), I tried reading the OpenImageIO documentation but still
> can't get the meaning... I suppose this is because I'm not really familiar
> with image processing and also because my native language isn't English,
> so maybe I'm missing some important point. Shouldn't it be
> specRecibida.nchannels * something, AutoStride ? or something like that?
>
> Do you have any other comment that could help me?
>
> Thanks again and I'm sorry if I'm bothering you.
>
> Deborah
>
> ---------- Mensaje reenviado ----------
> From: "Larry Gritz" <lg@larrygritz.com>
> To: <tiff@lists.maptools.org>
> Date: Mon, 8 Feb 2010 18:43:23 +0100
> Subject: [Tiff] OpenImageIO; was Re: fftw and TIFF files
> I'll take this opportunity to point people to another open source project
> I'm administering: http://www.openimageio.org
>
> OpenImageIO (OIIO for short) is a format-agnostic API for reading and
> writing image files. TIFF is among many image file formats supported
> (using libtiff underneath, of course). But even if you are only
> interested in TIFF, you may find that using OIIO's API's to read TIFF
> files is simpler and more straightforward than struggling with the raw
> libtiff calls. There are also a lot of other useful features of the
> library, including an image tile cache that lets you literally access
> hundreds of GB of image data without worrying about which parts are in
> memory or which files are opened, and a filtered texture system.
>
> But the aspect of OIIO that is relevant to Debora's question is that the
> basic API for reading images automatically does format conversion and will
> read data into buffers with strides. For example, your basic issue is
> that you want to read data from a TIFF file (perhaps with arbitrary bit
> depth) into a buffer of double[2], but you want the pixel values to end up
> in every other buffer slot. Piece of cake. You can do it with about 7
> lines of code:
>
> ImageInput *in = ImageInput::create (filename);
> ImageSpec spec;
> in->open (filename, spec); /* res is now in spec.{width,height} */
> fftw_complex *img1 = fftw_malloc(sizeof(fftw_complex) * spec.width
> * spec.height);
> memset (img1, 0, sizeof(fftw_complex) * spec.width * spec.height);
> // zero it out
> in->read_image (TypeDesc::DOUBLE /* desired data format */,
> pixels /* buffer */,
> 2*sizeof(double) /* optional: x stride */);
> in->close ();
> delete in;
>
> This will work for scanline or tiled images, any bit depth with proper
> conversion to double, etc. (Though as I've written it, the code assumes a
> single data channel. To be robust, it should check spec.nchannels before
> proceeding with the read_image.) Also, if you had the need to read other
> file formats, this code would not need to be modified, as long as it's a
> file format that OIIO understands or can find a plugin for.
>
> I hope you are using C++. If it's straight C, never mind.
>
> -- lg
>
>
> On Feb 8, 2010, at 8:48 AM, tiff-request@lists.maptools.org wrote:
>
> > ----------------------------------------------------------------------
> >
> > Date: Mon, 8 Feb 2010 11:47:27 +0100
> > From: "Gil, Debora, VF-ES (dgilalv) STU" <debora.gil@vodafone.com>
> > Subject: [Tiff] fftw and TIFF files
> > To: <tiff@lists.maptools.org>
> >
> > Hi,
> >
> > I'm trying to do the phase correlation of two TIFF images (a reference
> > image and an image received via fax) to determine if they are similar
> > and or have any offset.
> >
> > For this I'm using LibTIFF and FFTW. In order to do this I need to load
> > the Image data to the FFTW input arrays:
> >
> > fftw_complex *img1 = ( fftw_complex* )fftw_malloc( sizeof( fftw_complex
> > ) * width * height ); <- this is the input array (it's a double[2]
> > composed of the real and imaginary parts of a complex number)
> >
> > As I said, what I need to do is load the image data on that input array.
> > I would like to do something like this:
> >
> > for( i = 0; i < height ; i++ ) {
> > for( j = 0 ; j < width ; j++) {
> > img1[k][0] = <- here goes the image data
> > img1[k][1] = 0.0;
> > }
> > }
> >
> > This kind of thing is what I've seen in an OpenCV example for reading
> > TIFF images, but it doesn't seem to work so I decided to try with
> > LibTIFF.
> >
> > Thanks in advance,
> >
> > Debora
> >
>
> --
> Larry Gritz
> lg@larrygritz.com
>
>
> _______________________________________________
> Tiff mailing list: Tiff@lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/tiff
> http://www.remotesensing.org/libtiff/
>
>
>
> ---------- Mensaje reenviado ----------
> From: "Bob Friesenhahn" <bfriesen@simple.dallas.tx.us>
> To: "Gil, Debora, VF-ES (dgilalv) STU" <debora.gil@vodafone.com>
> Date: Mon, 8 Feb 2010 17:48:31 +0100
> Subject: Re: [Tiff] fftw and TIFF files
> On Mon, 8 Feb 2010, Gil, Debora, VF-ES (dgilalv) STU wrote:
>
> > Iʼm trying to do the phase correlation of two TIFF images (a reference
> > image and an image received
> > via fax) to determine if they are similar and or have any offset.
>
> Hi Debora,
>
> Thanks for introducing yourself and the problem you want to solve. We
> did receive your email. Your email was not formulated as a simple
> question that any of us can answer.
>
> Unless you are willing to perform a lot of libtiff-specific work to
> read images, then I suggest using an existing library on top of
> libtiff which simplifies the task for you, and allows using other
> image file formats as well.
>
> It may be that OpenCV is the ideal library for you and that you will
> achieve more success from discussing the issue with OpenCV developers.
>
> Bob
> --
> Bob Friesenhahn
> bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
>
>
>
>
>
> --
> Déborah
--
Larry Gritz
lg@larrygritz.com