/*!
Change the look up table (LUT) of an image. Considering pixel gray
level values \f$ l \f$ in the range \f$[A, B]\f$, this method allows
to rescale these values in \f$[A^*, B^*]\f$ by linear interpolation:
\f$
\left\{ \begin{array}{ll}
l \in ]-\infty, A] \mbox{, } & l = A^* \\
l \in [B, \infty[ \mbox{, } & l = B^* \\
l \in ]A, B[ \mbox{, } & l = A^* + (l-A) * \frac{B^*-A^*}{B-A}
\end{array}
\right.
\f$
\param I : Image to process.
\param A : Low gray level value of the range to consider.
\param A_star : New gray level value \f$ A^*\f$ to attribute to pixel
who's value was A
\param B : Height gray level value of the range to consider.
\param B_star : New gray level value \f$ B^*\f$ to attribute to pixel
who's value was B
\return The modified image.
\exception vpImageException::incorrectInitializationError If \f$B \leq A\f$.
As shown in the example below, this method can be used to binarize
an image. For an unsigned char image (in the range 0-255),
thresholding this image at level 127 can be done by:
\code
#include <visp3/core/vpImageTools.h>
#include <visp3/core/vpImage.h>
#include <visp3/io/vpImageIo.h>
int main()
{
vpImage<unsigned char> I;
#ifdef _WIN32
std::string filename("C:/temp/ViSP-images/Klimt/Klimt.ppm");
#else
std::string filename("/local/soft/ViSP/ViSP-images/Klimt/Klimt.ppm");
#endif
// Read an image from the disk
vpImageIo::read(I, filename);
// Binarize image I:
// - gray level values less than or equal to 127 are set to 0,
// - gray level values greater than 128 are set to 255
vpImageTools::changeLUT(I, 127, 0, 128, 255);
vpImageIo::write(I, "Klimt.pgm"); // Write the image in a PGM P5 image file format
}
\endcode
*/
void vpImageTools::changeLUT(vpImage<unsigned char>& I,
unsigned char A,
unsigned char A_star,
unsigned char B,
unsigned char B_star)
{
// Test if input values are valid
if (B <= A) {
vpERROR_TRACE("Bad gray levels") ;
throw (vpImageException(vpImageException::incorrectInitializationError ,
"Bad gray levels"));
}
unsigned char v;
double factor = (double)(B_star - A_star)/(double)(B - A);
for (unsigned int i=0 ; i < I.getHeight(); i++)
for (unsigned int j=0 ; j < I.getWidth(); j++) {
v = I[i][j];
if (v <= A)
I[i][j] = A_star;
else if (v >= B)
I[i][j] = B_star;
else
I[i][j] = (unsigned char)(A_star + factor*(v-A));
}
}
/*!
Sets all the parameters needed to read the video or the image sequence.
Grab the first frame and stores it in the image \f$ I \f$.
\param I : The image where the frame is stored.
*/
void vpVideoReader::open(vpImage< vpRGBa > &I)
{
if (!initFileName)
{
vpERROR_TRACE("The generic filename has to be set");
throw (vpImageException(vpImageException::noFileNameError,"filename empty"));
}
if (formatType == FORMAT_PGM ||
formatType == FORMAT_PPM ||
formatType == FORMAT_JPEG ||
formatType == FORMAT_PNG)
{
imSequence = new vpDiskGrabber;
imSequence->setGenericName(fileName);
imSequence->setImageNumber((int)firstFrame);
}
#ifdef VISP_HAVE_FFMPEG
else if (formatType == FORMAT_AVI ||
formatType == FORMAT_MPEG ||
formatType == FORMAT_MOV ||
formatType == FORMAT_OGV)
{
ffmpeg = new vpFFMPEG;
if(!ffmpeg->openStream(fileName, vpFFMPEG::COLORED))
throw (vpException(vpException::ioError ,"Could not open the video"));
ffmpeg->initStream();
}
#else
else if (formatType == FORMAT_AVI ||
formatType == FORMAT_MPEG ||
formatType == FORMAT_MOV ||
formatType == FORMAT_OGV)
{
vpERROR_TRACE("To read video files the FFmpeg library has to be installed");
throw (vpException(vpException::fatalError ,"the FFmpeg library is required"));
}
#endif
else if (formatType == FORMAT_UNKNOWN)
{
vpERROR_TRACE("The format of the file does not correpsond to a readable format.");
throw (vpException(vpException::fatalError ,"The format of the file does not correpsond to a readable format."));
}
frameCount = firstFrame;
if(!getFrame(I,firstFrame))
{
vpERROR_TRACE("Could not read the first frame");
throw (vpException(vpException::ioError ,"Could not read the first frame"));
}
height = I.getHeight();
width = I.getWidth();
isOpen = true;
findLastFrameIndex();
}
/*!
Sets all the parameters needed to read the video or the image sequence.
Grab the first frame and stores it in the image \f$ I \f$.
\param I : The image where the frame is stored.
*/
void vpVideoReader::open(vpImage<unsigned char> &I)
{
if (!initFileName)
{
vpERROR_TRACE("The generic filename has to be set");
throw (vpImageException(vpImageException::noFileNameError,"filename empty"));
}
if (isImageExtensionSupported())
{
imSequence = new vpDiskGrabber;
imSequence->setGenericName(fileName);
if (firstFrameIndexIsSet)
imSequence->setImageNumber(firstFrame);
}
else if (isVideoExtensionSupported())
{
#ifdef VISP_HAVE_FFMPEG
ffmpeg = new vpFFMPEG;
if (!ffmpeg->openStream(fileName, vpFFMPEG::GRAY_SCALED))
throw (vpException(vpException::ioError ,"Could not open the video with ffmpeg"));
ffmpeg->initStream();
#elif VISP_HAVE_OPENCV_VERSION >= 0x020100
capture.open(fileName);
if(!capture.isOpened())
{
throw (vpException(vpException::ioError ,"Could not open the video with opencv"));
}
#else
//vpERROR_TRACE("To read video files ViSP should be build with ffmpeg or opencv 3rd party libraries.");
throw (vpException(vpException::fatalError ,"To read video files ViSP should be build with ffmpeg or opencv >= 2.1.0 3rd party libraries."));
#endif
}
else if (formatType == FORMAT_UNKNOWN)
{
//vpERROR_TRACE("The format of the file does not correspond to a readable format.");
throw (vpException(vpException::fatalError ,"The format of the file does not correspond to a readable format supported by ViSP."));
}
findFirstFrameIndex();
frameCount = firstFrame;
if(!getFrame(I,firstFrame))
{
//vpERROR_TRACE("Could not read the video first frame");
throw (vpException(vpException::ioError ,"Could not read the video first frame"));
}
height = I.getHeight();
width = I.getWidth();
isOpen = true;
findLastFrameIndex();
frameCount = firstFrame; // open() should not increase the frame counter
}
/*!
It enables to set the path and the name of the file(s) which as/have to be read.
If you want to read a video file, \f$ filename \f$ corresponds to the path to the file (example : /local/video.mpeg).
If you want to read a sequence of images, \f$ filename \f$ corresponds to the path followed by the image name template. For exemple, if you want to read different images named image0001.jpeg, image0002.jpg, ... and located in the folder /local/image, \f$ filename \f$ will be "/local/image/image%04d.jpg".
\param filename : Path to a video file or file name template of a image sequence.
*/
void vpVideoReader::setFileName(const char *filename)
{
if (filename == '\0')
{
vpERROR_TRACE("filename empty ") ;
throw (vpImageException(vpImageException::noFileNameError,"filename empty ")) ;
}
strcpy(this->fileName,filename);
formatType = getFormat(fileName);
initFileName = true;
}
/*!
It enables to set the path and the name of the file(s) which as/have to be read.
If you want to read a video file, \f$ filename \f$ corresponds to the path to the file (example : /local/video.mpeg).
If you want to read a sequence of images, \f$ filename \f$ corresponds to the path followed by the image name template. For exemple, if you want to read different images named image0001.jpeg, image0002.jpg, ... and located in the folder /local/image, \f$ filename \f$ will be "/local/image/image%04d.jpg".
\param filename : Path to a video file or file name template of a image sequence.
*/
void vpVideoReader::setFileName(const char *filename)
{
if (!filename || *filename == '\0')
{
vpERROR_TRACE("filename empty ") ;
throw (vpImageException(vpImageException::noFileNameError,"filename empty ")) ;
}
if (strlen( filename ) >= FILENAME_MAX) {
throw(vpException(vpException::memoryAllocationError,
"Not enough memory to intialize the file name"));
}
strcpy(this->fileName,filename);
formatType = getFormat(fileName);
if (formatType == FORMAT_UNKNOWN) {
throw(vpException(vpException::badValue, "Filename extension not supported"));
}
initFileName = true;
}