Converting gif to mif

Hello:

I have obtained a .m file which converts a .gif file to .mif (memory initialization file for FPGAs). I am more on the hardware side of things so I only need matlab for this conversion. The code is as follows:

%%read the image and show it

name = 'leia';
img = imread(strcat(name,'.gif'));
g = im2double(img);
g = g/max(max(g));
rgb = cat(3,g,g,g);
imshow(rgb);

%%insert into 640 x 480 region

out = ones(480,640);
out(10+(1:480),90+(1:480)) = img;
imshow(out);

%%pack pixels

x = out';
x = uint8(x(:));
n = length(x);
y = reshape(x,8,n/8)';
z = y(:,8);
for i=1:7
    z = bitor(z,bitshift(y(:,i),8-i));
end

%%count runs

m = 0;
n = 1;
v = z(1);
for i=2:length(z)
    if (z(i)~=v)
        m = m + 1;
        value(m) = v;
        runlen(m) = n;
        n = 1;
        v = z(i);
    else
        n = n + 1;
    end
end
m = m + 1;
value(m) = v;
runlen(m) = n;

%%information

fprintf('total runs %d\n',sum(runlen));
fprintf('number of runs %d\n',length(runlen));
nz = length(find(value==0));
nf = length(find(value==255));

fprintf('zeros %d all ones %d\n',nz,nf);

%%create mif file

dfv = 255;
fid = fopen(strcat(name,'.mif'),'w');
str = 'WIDTH=8;\nDEPTH=38400;\n\nADDRESS_RADIX=HEX;\nDATA_RADIX=HEX;\n\n';
fprintf(fid,str);

str = 'CONTENT BEGIN\n   [0000..%04X]  : %X;\n';
fprintf(fid,str,sum(runlen)-1,dfv);

n = 0;
for k=1:length(runlen)
    if (runlen(k)==1)
        str = sprintf('   %04X : %X;\n', n, value(k));
    else
        str = sprintf('   [%04X..%04X] : %X;\n', n, n+runlen(k)-1, value(k));
    end
    if (value(k) ~= dfv)
        fprintf(fid,str);
    end
    n = n + runlen(k);
end
fprintf(fid,'END;\n');
fclose(fid);

I get an error as follows:

Subscripted assignment dimension mismatch. Error in xxxxxx (line 15) out(10+(1:480),90+(1:480)) = img;

The image I am using is a 640x480 gif attached to this post. I tried other gifs of the same size with no luck.

Any help would be much appreciated. Thanks!

[Olawale Akinwale]

The problem comes from the fact that img has three dimensions (one for r, one for g and one for b) but your variable "out" has just two dimensions! Maybe you might want to convert the image first to Y,cr,cb and then resize / use the two-dimensional Y array,

Answer 1

[Image Analyst]

1:480 is a 480 element long vector. You need a two element long vector, [row1, row2]:

out(10+[1, size(img, 1)-1], 90 + [1, size(img, 2)-1]) = img;

in order to paste img into out. Or more readable and maintainable is this

row1 = 10;
row2 = row1 + size(img, 1) - 1;
col1 = 90;
col2 = col1 + size(img, 2) - 1;
out(row1 : row2, col1 : col2) = img;

[blueprint]

Thanks Image Analyst! The latter approach worked with col2 = col1 + .... (assuming a typo)

Now received this error however: Error using reshape Size arguments must be real integers .

Error in xxxxx y = reshape(x,8,n/8)';

I'm assuming this has to do with the "/8" parameter. Any suggestions on how to avoid this in Matlab based on your expertise (given the above code)?

Thanks for the help in advance.

[Image Analyst]

You're welcome. Please mark the answer as Accepted since it worked.

What is n? It's probably not a multiple of 8. And is 8 rows times (n/8) columns going to equal rows*columns of your original image? If not, then you're changing the number of elements, which you can't do. If your original image has a million pixels, then when it's reshaped it must also have a million pixels, not any other number.