how to convert dicom image to png

Hi all,

i want to convert my dicom image to png image.

below my coding, but error. Anyone can help me?

[I, map]=dicomread('lung.dcm');
imwrite(I,map,'lung.png','png');

ERRORR!!!!

Error using imwrite>parse_inputs (line 628)
The colormap should have three columns.

Error in imwrite (line 440)
[data, map, filename, format, paramPairs] = parse_inputs(varargin{:});

CAN HELP ME?

Answer 1

[Image Analyst]

I imagine you looked at what map was. Did that not give you any clue as to why it was not 3 columns? What was it? Maybe it's empty, in which case you'd not pass it in to imwrite.

[mohd akmal masud]

yes, no clue. i also feel empty.

do you have any idea image analyst?

[Image Analyst]

It probably is empty. Did you try not using it in imwrite() like I suggested? If not, why not? And attach your dcm image, zipped up if you have to.

[mohd akmal masud]

ok sure. here attached.

[Image Analyst]

Like I said, map is empty so it was not saved with any pseudocolor lookup table colormap. You can simply save it without the map like I said.

[grayImage, map] = dicomread(fullFileName);
outputFileName = strrep(fullFileName, '.dcm', '.png');
if isempty(map)
    imwrite(grayImage, outputFileName);
else
    rgbImage = ind2rgb(grayImage, map);
    imwrite(rgbImage, outputFileName);
end

Did you do that?

[mohd akmal masud]

yes, i did. but error.

[grayImage, map] = dicomread('lung.dcm');
outputFileName = strrep('lung.dcm', '.dcm', '.png');
if isempty(map)
    imwrite(grayImage, outputFileName);
else
    rgbImage = ind2rgb(grayImage, map);
    imwrite(rgbImage, outputFileName);
end

ERROR

Warning: Data loss and unexpected results may occur with signed pixel data. 
> In imwrite (line 469)
In tukartopng (line 4) 
Error using writepng>parseInputs (line 290)
Expected input to be one of these types:

double, single, logical, uint8, uint16

Instead its type was int16.

Error in writepng (line 20)
[results, unmatched] = parseInputs(data,map,filename,varargin{:});

Error in imwrite (line 566)
        feval(fmt_s.write, data, map, filename, paramPairs{:});

Error in tukartopng (line 4)
    imwrite(grayImage, outputFileName);

[mohd akmal masud]

also error for change to RGB

>> [grayImage, map] = dicomread('lung.dcm');
>> rgbImage = ind2rgb(grayImage, map);
Index in position 1 exceeds array bounds.

Error in matlab.images.internal.ind2rgb (line 24)
rgb(1:height, 1:width, 1) = reshape(cm(indexedImage, 1), [height width]);

Error in ind2rgb (line 17)
    r = matlab.images.internal.ind2rgb(a, cm);

[Image Analyst]

You can't do that. You have to do it like I showed you - inside an "if" block. You can't convert a gray scale or indexed image to RGB if there is no colormap.

And for the gray scale image I assume you got that working already by doing what it told you and casting your image to uint8 with the im2uint8() or uint8() function

grayImage = im2uint8(grayImage);
imwrite(grayImage, outputFileName);

[mohd akmal masud]

oh i see..mean there is no map, then cannot convert it to RGB.

yes, for im2unit8 done.

thank you sir for your explanation. thank you so much.