Problems using geotiffwrite with colormap

I have a .png file and his associated .wld file. I’m using “imread” and “worldfileread” to load both files into Matlab and write them back in “tif” format.

It’s working great, but the file is saved without a color map. So I tried to load the original color map and save it together, but for some reason, I get the error:

Error using geotiffwrite

Function GEOTIFFWRITE expected its third input argument CMAP to be a valid colormap. Valid colormaps must be nonempty, double, 2-D matrices with 3 columns.

As far as I can see, the cmap is a double, 2-D matrix with 3 columns.

Maybe somebody has a solution for that?

The files and script are attached.

Thanks!

[image,cmap] = imread('ABX_N0Q_202109290033.png');
R = worldfileread('ABX_N0Q_202109290033.wld',"geographic",size(image));
geotiffwrite('test.tif', image, R,cmap);

Answer 1

[Yuvraj Singh]

Hi Amit,

geotiffwrite('test.tif', image, R,cmap);

'geotiffwrite' expects its third argument to be cmap, in the code mentioned above cmap is the fourth argument.

Refer to the below documentation for the right syntax.

Write GeoTIFF file - MATLAB geotiffwrite (mathworks.com)

[Amit Kallush]

Thanks that was really helpful! I didnt realise that it should come as the third value. now its working

Thanks!