matlab-(含教程)基于SPIHT-DWT算法的图像压缩加密解压缩解密过程实现matlab仿真

function out = encoding(m, max_bits, block_size, level) figure; imshow(m); bitctr = 0; out = 2*ones(1,max_bits); n_max = floor(log2(abs(max(max(m)')))); Bits_Header = 0; Bits_LSP = 0; Bits_LIP = 0; Bits_LIS = 0; out(1,[1 2 3]) = [size(m,1) n_max level]; bitctr = bitctr + 24; index = 4; Bits_Header = Bits_Header + 24; %----------- Initialize LIP, LSP, LIS ---------------- temp = []; bandsize = 2.^(log2(size(m, 1)) - level + 1); temp1 = 1 : bandsize; for i = 1 : bandsize temp = [temp; temp1]; end LIP(:, 1) = temp(:); temp = temp'; LIP(:, 2) = temp(:); LIS(:, 1) = LIP(:, 1); LIS(:, 2) = LIP(:, 2); LIS(:, 3) = zeros(length(LIP(:, 1)), 1); pstart = 1; pend = bandsize / 2; for i = 1 : bandsize / 2 LIS(pstart : pend, :) = []; pdel = pend - pstart + 1; pstart = pstart + bandsize - pdel; pend = pend + bandsize - pdel; end LSP = []; n = n_max; %coding while(bitctr < max_bits) % Sorting Pass LIPtemp = LIP; temp = 0; for i = 1:size(LIPtemp,1) temp = temp+1; if (bitctr + 1) >= max_bits if (bitctr < max_bits) out(length(out))=[]; end return end if abs(m(LIPtemp(i,1),LIPtemp(i,2))) >= 2^n % 1: positive; 0: negative out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIP = Bits_LIP + 1; sgn = m(LIPtemp(i,1),LIPtemp(i,2))>=0; out(index) = sgn; bitctr = bitctr + 1; index = index +1; Bits_LIP = Bits_LIP + 1; LSP = [LSP; LIPtemp(i,:)]; LIP(temp,:) = []; temp = temp - 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIP = Bits_LIP + 1; end end LIStemp = LIS; temp = 0; i = 1; while ( i <= size(LIStemp,1)) temp = temp + 1; if LIStemp(i,3) == 0 if bitctr >= max_bits return end max_d = func_MyDescendant(LIStemp(i,1),LIStemp(i,2),LIStemp(i,3),m); if max_d >= 2^n out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; x = LIStemp(i,1); y = LIStemp(i,2); if (bitctr + 1) >= max_bits if (bitctr < max_bits) out(length(out))=[]; end return end if abs(m(2*x-1,2*y-1)) >= 2^n LSP = [LSP; 2*x-1 2*y-1]; out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; sgn = m(2*x-1,2*y-1)>=0; out(index) = sgn; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; LIP = [LIP; 2*x-1 2*y-1]; end if (bitctr + 1) >= max_bits if (bitctr < max_bits) out(length(out))=[]; end return end if abs(m(2*x-1,2*y)) >= 2^n LSP = [LSP; 2*x-1 2*y]; out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; sgn = m(2*x-1,2*y)>=0; out(index) = sgn; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; LIP = [LIP; 2*x-1 2*y]; end if (bitctr + 1) >= max_bits if (bitctr < max_bits) out(length(out))=[]; end return end if abs(m(2*x,2*y-1)) >= 2^n LSP = [LSP; 2*x 2*y-1]; out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; sgn = m(2*x,2*y-1)>=0; out(index) = sgn; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; LIP = [LIP; 2*x 2*y-1]; end if (bitctr + 1) >= max_bits if (bitctr < max_bits) out(length(out))=[]; end return end if abs(m(2*x,2*y)) >= 2^n LSP = [LSP; 2*x 2*y]; out(index) = 1; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; sgn = m(2*x,2*y)>=0; out(index) = sgn; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; LIP = [LIP; 2*x 2*y]; end if ((2*(2*x)-1) < size(m) & (2*(2*y)-1) < size(m)) LIS = [LIS; LIStemp(i,1) LIStemp(i,2) 1]; LIStemp = [LIStemp; LIStemp(i,1) LIStemp(i,2) 1]; end LIS(temp,:) = []; temp = temp-1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; end else if bitctr >= max_bits return end max_d = func_MyDescendant(LIStemp(i,1),LIStemp(i,2),LIStemp(i,3),m); if max_d >= 2^n out(index) = 1; bitctr = bitctr + 1; index = index +1; x = LIStemp(i,1); y = LIStemp(i,2); LIS = [LIS; 2*x-1 2*y-1 0; 2*x-1 2*y 0; 2*x 2*y-1 0; 2*x 2*y 0]; LIStemp = [LIStemp; 2*x-1 2*y-1 0; 2*x-1 2*y 0; 2*x 2*y-1 0; 2*x 2*y 0]; LIS(temp,:) = []; temp = temp - 1; else out(index) = 0; bitctr = bitctr + 1; index = index +1; Bits_LIS = Bits_LIS + 1; end end i = i+1; end % Refinement Pass temp = 1; value = floor(abs(2^(n_max-n+1)*m(LSP(temp,1),LSP(temp,2)))); while (value >= 2^(n_max+2) & (temp <= size(LSP,1))) if bitctr >= max_bits return end s = bitget(value,n_max+2); out(index) = s; bitctr = bitctr + 1; index = index +1; Bits_LSP = Bits_LSP + 1; temp = temp + 1; if temp <= size(LSP,1) value = floor(abs(2^(n_max-n+1)*m(LSP(temp,1),LSP(temp,2)))); end end n = n - 1; end