Hi all,

I am using Qwt Raster Matrix Data to develop spectrogram plot. Data that is used for presenting contours is data from file. Usually, it is the matrix of around 50 - 100 rows and 5 - 20 columns. After attaching it to the Qwt Raster Matrix Data, I use it produce spectrogram using Spectrogram Class. Then I attach spectrogram to Qwt Plot.

Everything works fine, values of spectrogram are ok. But beacause data used is not very dense, my contour is filled with bunch of rectangulars of different colours. When I use Octave for displaying same data, I get very smooth, "non - pixelised" contours.

From what I read in documentation of Qwt Raster Matrix Data, it uses by default next neighbour interpolation algorithm. My question is: Am I missing a point here and next neighbour interpolation in QwtRasterMatrixData isn't used for smoothing the contour plot and some seperate algorithm should be used for it?

Thank you in advance for your answers.