quantexpofn.m

非常好的数字处理教程

function quantexpofn(action, datastruct)

if nargin < 1
	action='init';
end

name = mfilename;
figname = [name(1:end-2) '_fig'];
f=findobj('Tag',figname);
handles = get(f,'UserData');

switch action
	case 'help'
		display_help(figname);
	case 'init'
		setdefaults;
		movegui(f,'center');
		reset(handles.pdfplot);
		reset(handles.quantplot);
		makepdfplot(handles);
		makequantplot(handles);
		[x,y,D,H] = findquantize(handles);
		handles.quant.x = x;
		handles.quant.y = y;
		handles.quant.D = D;
		handles.quant.H = H;
		updatepdfplot(handles);
		updatequantplot(handles);
	case 'resize'
		movegui(f,'onscreen');
	case 'updateall'
		[x,y,D,H] = findquantize(handles);
		handles.quant.x = x;
		handles.quant.y = y;
		handles.quant.D = D;
		handles.quant.H = H;
		updatepdfplot(handles);
		updatequantplot(handles);
	case 'updatequant'
	case 'printlevels'
		disp(handles.quant.x)
		disp(handles.quant.y)
		disp(['Distortion = ' num2str(handles.quant.D)])
		disp(['SQNR = ' num2str(10*log10(str2num(get(handles.pdfvar,'String'))/handles.quant.D))])
	case 'apply'
		handles.audiodata = load_audiodata;
		if ~isfield(handles.audiodata, 'filenamepath')
			return;
		end
		if (size(handles.audiodata.data,2) > 1)
			handles.audiodata.data = normalize(to_mono(handles.audiodata.data));
		end
		handles.qaudiodata = handles.audiodata;
		[handles.qaudiodata.data, D] = quantizedata(handles.audiodata.data, ...
			handles.quant.x, handles.quant.y);
		set(handles.play_orig,'Visible','on');
		set(handles.play_quant,'Visible','on');
	case 'play_orig'
		if isfield(handles,'audiodata')
			play_audiodata(handles.audiodata);
		end
	case 'play_quant'
		if isfield(handles,'audiodata')
			play_audiodata(handles.qaudiodata);
		end
	case 'show'
		updatepdfplot(handles);
	case 'print'
		print_figure(f);
	case 'close'
		close_figure(f,figname(1:end-4));
		return;
end
set(f,'UserData',handles);

% --------------------------------------------------------------------

function makepdfplot(handles);
axes(handles.pdfplot);
set(handles.pdfplot,'XLim',[-2 2],'YLim',[-0.1 1],'YTick',[]);
xlabel('x');
ylabel('Density');

function makequantplot(handles);
axes(handles.quantplot);
set(handles.quantplot,'XLim',[-2 2],'YLim',[-2 2]);
xlabel('Input');
ylabel('Quantization');

% --------------------------------------------------------------------
function updatepdfplot(handles)
	sig2 = str2num(get(handles.pdfvar,'String'));
	pdftype = get(handles.pdfmenu,'String');
	[fx,x] = getpdf(lower(pdftype{get(handles.pdfmenu,'Value')}),sig2);
	axes(handles.pdfplot);
	cla;
	plot(x,fx,'LineWidth',2);
	hold on;
	line([-300*sqrt(sig2) 300*sqrt(sig2)],[0 0]);
	
	if get(handles.showL,'Value')
		plot(handles.quant.y,zeros(1,length(handles.quant.y)),'ko','MarkerSize',8);
	end
	
	if get(handles.showR,'Value')
		for i=1:length(handles.quant.y)+1
			line([handles.quant.x(i) handles.quant.x(i)],[-1 1], ...
				'Color','k','LineStyle','--');
		end
	end

	yq = handles.quant.y;
	axis([-max(3*sqrt(sig2), 1.2*yq(end)) max(3*sqrt(sig2), 1.2*yq(end)) ...
		-0.1 max(0.5,max(fx))]);
	set(handles.pdfplot,'YTick',[]);
	xlabel('x');
	ylabel('Density');
	distype = get(handles.distmenu,'String');
	switch lower(distype{get(handles.distmenu,'Value')})
		case 'squared error'
			title(['Distortion = ' num2str(handles.quant.D) '    SQNR = ' ...
				num2str(10*log10(sig2/handles.quant.D)) ' dB   Entropy = ' ...
				num2str(handles.quant.H)]);
		otherwise
			N = str2num(get(handles.nlevels,'String'));
			pdftype = get(handles.pdfmenu,'String');
			if rem(N,2) == 0
				x = handles.quant.x(N/2+1:end);
				y = handles.quant.y(N/2+1:end);
			else
				x = handles.quant.x((N+1)/2+1:end);
				y = handles.quant.y((N+1)/2:end);
			end
			No = getNoisePower(x,y,sig2, ...
				lower(pdftype{get(handles.pdfmenu,'Value')}));
			
			title(['Distortion = ' num2str(handles.quant.D) '    SQNR = ' ...
				num2str(10*log10(sig2/No)) ' dB   Entropy = ' ...
				num2str(handles.quant.H)]);
	end


function updatequantplot(handles);
	N = str2num(get(handles.nlevels,'String'));
	sig2 = str2num(get(handles.pdfvar,'String'));

	xq = handles.quant.x;
	yq = [handles.quant.y handles.quant.y(end)];
	xq(find(abs(xq)==Inf)) = 1000*sign(xq(find(abs(xq)==Inf)));
	axes(handles.quantplot);
	cla;
	stairs(xq,yq);
	hold on;
	line([1.1*yq(1) 1.1*yq(N)],[0 0],'Color','k','LineStyle','--');
	line([0 0],[1.1*yq(1) 1.1*yq(N)],'Color','k','LineStyle','--');
	axis([1.1*yq(1) 1.1*yq(N) 1.1*yq(1) 1.1*yq(N)]);
	set(handles.quantplot,'XTick',xq,'YTick',yq(1:end-1));
	grid on;

	
function [fx,x] = getpdf(type,var)
	switch type
		case 'uniform'
			V = sqrt(3*var);
			x = [-6*V:0.01:6*V];
			fx = zeros(1,length(x));
			fx(find(abs(x)<=V)) = 1/(2*V);
		case 'gaussian'
			x = [-6*sqrt(var):0.01:6*sqrt(var)];
			fx = 1/(sqrt(2*pi*var))*exp(-x.^2/(2*var));
		case 'laplacian'
			l = sqrt(2/var);
			x = [-60/l:0.01:60/l];
			fx = (l/2)*exp(-l*abs(x));
	end


function [x,y,D,H] = findquantize(handles)

	N = str2num(get(handles.nlevels,'String'));
	var = str2num(get(handles.pdfvar,'String'));
	sig = sqrt(var);
	quantype = get(handles.quantmenu,'String');
	pdftype = get(handles.pdfmenu,'String');

	distype = get(handles.distmenu,'String');
	
	switch lower(pdftype{get(handles.pdfmenu,'Value')})
		case 'uniform'
			[x,y,D,H] = quniform(N,var, ...
				lower(quantype{get(handles.quantmenu,'Value')}), ...
				lower(distype{get(handles.distmenu,'Value')}));
		case 'gaussian'
			[x,y,D,H] = qgauss(N,var, ...
				lower(quantype{get(handles.quantmenu,'Value')}), ...
				lower(distype{get(handles.distmenu,'Value')}));
		case 'laplacian'
			[x,y,D,H] = qlaplace(N,var, ...
				lower(quantype{get(handles.quantmenu,'Value')}), ...
				lower(distype{get(handles.distmenu,'Value')}));

	end