How can I convert base64 encoded data URL to a PNG image?

I have image data in the form of base64 encoded data URLs, like this:

'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABdwAAAK8CAYAAAD1...'

I need to convert these to either some common image format, such as PNG, or JPEG, or directly to a matrix describing the image.

Matlab provides "webread" to read data from web services, but this does not support the "data:" protocol.

Is there a way to use Matlab to read data URLs?

Answer 1

[T.Nikhil kumar]

Hello David,

I understand that you are looking for a way to convert your image in form of base64 data to a PNG/JPEG.

I would suggest you to use ‘matlab.net.base64decode’ function for this purpose. After decoding, you will get the binary representation of the image. You can write this binary data to a file with the appropriate extension (e.g., .png, .jpeg) using ‘fwrite’. Follow the steps as mentioned below:

- You first need to extract the base64 encoded part of the data URL, which is the portion after the comma.

dataURL = 'data:image/png;base64,iVBORw0KGgoAAAANSUh…..==';
commaIndex = strfind(dataURL, ',');
base64String = dataURL(commaIndex+1:end);

- Decode the base64 string using the ‘matlab.net.base64decode’ function.

decodedBytes = matlab.net.base64decode(base64String);

- Write the data to an image File

fileName = 'outputImage.png'; % or .jpeg, depending on the data
fid = fopen(fileName, 'wb');
fwrite(fid, decodedBytes);
fclose(fid);

Now you have your image ‘outputImage.png’ saved in the current folder.

Refer to the following documentation for more understanding of functions used above:

matlab.net.base64decode - https://www.mathworks.com/help/matlab/ref/matlab.net.base64decode.html

fopen, fwrite and fclose - https://www.mathworks.com/help/matlab/low-level-file-i-o.html

Hope this helps!

[David]

Thank you, this works perfectly!