Error in my Image COMPRESSION code USING DCT2D in matlab
https://stackoverflow.com/questions/18299035
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24-06-2022 - |
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I'm trying to fix a program already exists, but there is always this error "Error in ==> DCT1 at 254 decm_eq BIN2DEC = ([I_runcode (a, b) code (1 + m * (c_indx-1). M * c_indx) DEC2BIN (0 bpp_diff)]). "I do not know what to do. Please help me
%% LOSSY COMPRESSION-DECOMPRESSION USNIG DISCRETE COSINE TRANSFORM TECHNIQUE.
function[]=dct1(filename,n,m)
% "filename" is the string of characters including Image name and its
% extension.
% "n" denotes the number of bits per pixel.
% "m" denotes the number of most significant bits (MSB) of DCT Coefficients.
% Matrix Intializations.
N=8; % Block size for which DCT is Computed.
M=8;
I=imread(filename); % Reading the input image file and storing intensity values in 2-D matrix I.
I_dim=size(I); % Finding the dimensions of the image file.
I_Trsfrm.block=zeros(N,M); % Initialising the DCT Coefficients Structure Matrix "I_Trsfrm" with the required dimensions.
Norm_Mat=[16 11 10 16 24 40 51 61 % Normalization matrix (8 X 8) used to Normalize the DCT Matrix.
12 12 14 19 26 58 60 55
14 13 16 24 40 57 69 56
14 17 22 29 51 87 80 62
18 22 37 56 68 109 103 77
24 35 55 64 81 104 113 92
49 64 78 87 103 121 120 101
72 92 95 98 112 100 103 99];
save('LenaInitial.txt','I');
%% PART-1: COMPRESSION TECHNIQUE.
% Computing the Quantized & Normalized Discrete Cosine Transform.
% Y(k,l)=(2/root(NM))*c(k)*c(l)*sigma(i=0:N-1)sigma(j=0:M-1)y(i,j)cos(pi(2i+1)k/(2N))cos(pi(2j+1)l/(2M))
% where c(u)=1/root(2) if u=0
% = 1 if u>0
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
for k=1:N
for l=1:M
prod=0;
for i=1:N
for j=1:M
prod=prod+double(I(N*(a-1)+i,M*(b-1)+j))*cos(pi*(k-1)*(2*i-1)/(2*N))*cos(pi*(l-1)*(2*j-1)/(2*M));
end
end
if k==1
prod=prod*sqrt(1/N);
else
prod=prod*sqrt(2/N);
end
if l==1
prod=prod*sqrt(1/M);
else
prod=prod*sqrt(2/M);
end
I_Trsfrm(a,b).block(k,l)=prod;
end
end
% Normalizing the DCT Matrix and Quantizing the resulting values.
I_Trsfrm(a,b).block=round(I_Trsfrm(a,b).block./Norm_Mat);
end
end
% zig-zag coding of the each 8 X 8 Block.
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
I_zigzag(a,b).block=zeros(1,0);
freq_sum=2:(N+M);
counter=1;
for i=1:length(freq_sum)
if i<=((length(freq_sum)+1)/2)
if rem(i,2)~=0
x_indices=counter:freq_sum(i)-counter;
else
x_indices=freq_sum(i)-counter:-1:counter;
end
index_len=length(x_indices);
y_indices=x_indices(index_len:-1:1); % Creating reverse of the array as "y_indices".
for p=1:index_len
if I_Trsfrm(a,b).block(x_indices(p),y_indices(p))<0
bin_eq=dec2bin(bitxor(2^n-1,abs(I_Trsfrm(a,b).block(x_indices(p),y_indices(p)))),n);
else
bin_eq=dec2bin(I_Trsfrm(a,b).block(x_indices(p),y_indices(p)),n);
end
I_zigzag(a,b).block=[I_zigzag(a,b).block,bin_eq(1:m)];
end
else
counter=counter+1;
if rem(i,2)~=0
x_indices=counter:freq_sum(i)-counter;
else
x_indices=freq_sum(i)-counter:-1:counter;
end
index_len=length(x_indices);
y_indices=x_indices(index_len:-1:1); % Creating reverse of the array as "y_indices".
for p=1:index_len
if I_Trsfrm(a,b).block(x_indices(p),y_indices(p))<0
bin_eq=dec2bin(bitxor(2^n-1,abs(I_Trsfrm(a,b).block(x_indices(p),y_indices(p)))),n);
else
bin_eq=dec2bin(I_Trsfrm(a,b).block(x_indices(p),y_indices(p)),n);
end
I_zigzag(a,b).block=[I_zigzag(a,b).block,bin_eq(1:m)];
end
end
end
end
end
% Clearing unused variables from Memory space
clear I_Trsfrm prod;
clear x_indices y_indices counter;
% Run-Length Encoding the resulting code.
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
% Computing the Count values for the corresponding symbols and
% savin them in "I_run" structure.
count=0;
run=zeros(1,0);
sym=I_zigzag(a,b).block(1);
j=1;
block_len=length(I_zigzag(a,b).block);
for i=1:block_len
if I_zigzag(a,b).block(i)==sym
count=count+1;
else
run.count(j)=count;
run.sym(j)=sym;
j=j+1;
sym=I_zigzag(a,b).block(i);
count=1;
end
if i==block_len
run.count(j)=count;
run.sym(j)=sym;
end
end
% Computing the codelength needed for the count values.
dim=length(run.count); % calculates number of symbols being encoded.
maxvalue=max(run.count); % finds the maximum count value in the count array of run structure.
codelength=log2(maxvalue)+1;
codelength=floor(codelength);
% Encoding the count values along with their symbols.
I_runcode(a,b).code=zeros(1,0);
for i=1:dim
I_runcode(a,b).code=[I_runcode(a,b).code,dec2bin(run.count(i),codelength),run.sym(i)];
end
end
end
% Saving the Compressed Code to Disk.
save ('LenaCompressed.txt','I_runcode');
% Clearing unused variables from Memory Space.
clear I_zigzag run;
%% PART-2: DECOMPRESSION TECHNIQUE.
% Run-Length Decoding of the compressed image.
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
enc_str=I_runcode(a,b).code;
% Computing the length of the encoded string.
enc_len=length(enc_str);
% Since Max. Count is unknown at the receiver, Number of bits used for each
% count value is unknown and hence cannot be decoded directly. Number of bits
% used for each count can be found out by trial and error method for all
% the possible lengths => factors of encoded string length.
% Computing the non-trivial factors of the "enc_len" (length of encoded
% string) i.e., factors other than 1 & itself.
factors_mat=zeros(1,0);
if enc_len<=(n+1)
realfact=enc_len;
else
for i=2:enc_len-2 % "enc_len-1" is always not a divisor of "enc_len".
if(rem(enc_len,i)==0)
factors_mat=[factors_mat,i];
end
end
% Trial and Error Method to Find the Exact count value.
for i=1:length(factors_mat)
flagcntr=0;
temp_dim=enc_len/factors_mat(i);
for j=1:temp_dim
if strcmp(enc_str(1+(j-1)*factors_mat(i):j*factors_mat(i)),dec2bin(0,factors_mat(i)))==0
if j==1
flagcntr=flagcntr+1;
else
if enc_str((j-1)*factors_mat(i))~=enc_str(j*factors_mat(i))
flagcntr=flagcntr+1;
else
break;
end
end
else
break;
end
end
if flagcntr==temp_dim
realfact=factors_mat(i);
break;
end
end
end
% Clearing unused variables from Memory space
clear factors_mat flagcntr j
% Finding out the count values of corresponding symbols in the encoded
% string and then decoding it accordingly.
dec_str=zeros(1,0);
temp_dim=enc_len/realfact;
for i=1:temp_dim
count_str=enc_str(1+(i-1)*realfact:(i*realfact)-1);
countval=bin2dec(count_str);
for j=1:countval
dec_str=[dec_str,enc_str(i*realfact)];
end
end
I_runcode(a,b).code=dec_str;
end
end
% Clearing unused variables from Memory space
clear enc_str dec_str temp_dim realfact enc_len
clear countval count_str
% Reconstructing the 8 X 8 blocks in Zig-Zag fashion.
I_rec_Trnsfm.block=zeros(N,M);
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
bpp=length(I_runcode(a,b).code)/(N*M); % "bpp" is the bits-per-pixel in reconstruction of image.
bpp_diff=n-bpp;
freq_sum=2:(N+M);
counter=1;
c_indx=1;
for i=1:length(freq_sum)
if i<=((length(freq_sum)+1)/2)
if rem(i,2)~=0
x_indices=counter:freq_sum(i)-counter;
else
x_indices=freq_sum(i)-counter:-1:counter;
end
index_len=length(x_indices);
y_indices=x_indices(index_len:-1:1); % Creating reverse of the array as "y_indices".
for p=1:index_len
decm_eq=bin2dec([I_runcode(a,b).code(1+m*(c_indx-1):m*c_indx),dec2bin(0,bpp_diff)]);
if decm_eq>(2^(n-1))-1
decm_eq=decm_eq-(2^n-1);
end
I_rec_Trnsfm(a,b).block(x_indices(p),y_indices(p))=decm_eq;
c_indx=c_indx+1;
end
else
counter=counter+1;
if rem(i,2)~=0
x_indices=counter:freq_sum(i)-counter;
else
x_indices=freq_sum(i)-counter:-1:counter;
end
index_len=length(x_indices);
y_indices=x_indices(index_len:-1:1); % Creating reverse of the array as "y_indices".
for p=1:index_len
decm_eq=bin2dec([I_runcode(a,b).code(1+m*(c_indx-1):m*c_indx),dec2bin(0,bpp_diff)]);
if decm_eq>(2^(n-1))-1
decm_eq=decm_eq-(2^n-1);
end
I_rec_Trnsfm(a,b).block(x_indices(p),y_indices(p))=decm_eq;
c_indx=c_indx+1;
end
end
end
end
end
% Clearing unused variables from Memory space
clear I_runcode x_indices y_indices
clear c_indx freq_sum
% Denormalizing the Reconstructed Tranform matrix using the same
% Normalization matrix.
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
I_rec_Trnsfm(a,b).block=(I_rec_Trnsfm(a,b).block).*Norm_Mat;
end
end
% Inverse-Discrete Cosine Transform on the reconstructed Matrix.
% y(i,j)=(2/root(NM))*sigma(i=0:N-1)sigma(j=0:M-1) Y(k,l)c(k)*c(l)*cos(pi(2i+1)k/(2N))cos(pi(2j+1)l/(2M))
% where c(u)=1/root(2) if u=0
% = 1 if u>0
for a=1:I_dim(1)/N
for b=1:I_dim(2)/M
for i=1:N
for j=1:M
prod=0;
for k=1:N
for l=1:M
if k==1
temp=double(sqrt(1/2)*I_rec_Trnsfm(a,b).block(k,l))*cos(pi*(k-1)*(2*i-1)/(2*N))*cos(pi*(l-1)*(2*j-1)/(2*M));
else
temp=double(I_rec_Trnsfm(a,b).block(k,l))*cos(pi*(k-1)*(2*i-1)/(2*N))*cos(pi*(l-1)*(2*j-1)/(2*M));
end
if l==1
temp=temp*sqrt(1/2);
end
prod=prod+temp;
end
end
prod=prod*(2/sqrt(M*N));
I_rec((a-1)*N+i,(b-1)*M+j)=prod;
end
end
end
end
% Clearing unused variables from Memory Space.
clear I_rec_Trnsfm
% Displaying the Reconstructed Image.
diff=im2double(I)*255-I_rec;
diff=diff/max(max(diff));
diff=im2uint8(diff);
I_rec=I_rec/max(max(I_rec));
I_rec=im2uint8(I_rec);
% figure,imshow(I_rec,[0,2^n-1]);
% figure,imshow(diff,[0 2^n-1])
figure, imhist(I_rec);
figure, imhist(diff);
No correct solution
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