Image Processing; converting images

Hi guys. I have images in .im7 format. I've loaded them into Matlab using PivMat and ReadIMX, then formatted them into .mat files ( images ? ). Now, I'm trying to covert them to either .jpg , .tif , .png , .bmp using imwrite but I cannot do so because 'type was struct'. Can I efficiently go from 'structure' format to any of the formats that imwrite recognizes ?

[KSSV]

You have to extract the required pixel information from the structure and use imwrite.

[Damian Wierzbicki]

Thank you. If you don't mind me asking: what information would that be ? x ( 1x2048 double ) and y ( 1x2048 double ) and also w ( 2048x2048 double) also the unitx and unity are 'mm' - how'd I deal with that ? These are probably really stupid question, but I just want to make sure if I'm doing it wright.

Answer 1

[KSSV]

You need to pick the matrix 2048*2048 and use imwrite

https://in.mathworks.com/help/matlab/ref/imwrite.html

[Damian Wierzbicki]

Thank you again. When I'm trying to do so it spits 'Too many output arguments' out. Do you know why ?

[KSSV]

Give the code what you have tried...You should only send the required matrix into imwrite

A = rand(2048);
imwrite(A,'myimage.png')

[KSSV]

I guess you used something like

out = imwrite() ;

No imwrite doesn't give you any ouput, it writes your matrix into the filename and format which you have specified in the given folder.

[Damian Wierzbicki]

yes, I was doing that. Thank you so much. But now, even when I do it as I should have been doing, it displays a white rectangle

[KSSV]

What data does matrix have? Attach it.

[Damian Wierzbicki]

The file is too big to attach it. The entries of the matrix are integers ranging from 100 to above 1000 if that helps ?

[Thorsten]

Imwrite assumes double input data to be in the range [0, 1]. Everything above 1 will be mapped to 1, resulting in an all-white image. So you have to map your data to the range [0, 1].

[Damian Wierzbicki]

Thank you Thorsten, used mapminmax to map my data to desired range, not sure if that's what you meant ? It now displays the image ok, but with horizontal black thin lines ? There are also, hardly visible, white thin vertical lines along the image ? Any idea what might be causing it ?

Answer 2

[Image Analyst]

Try this:

storedStructure = load(filename)  % Don't use semicolon
% Now extract the image field into its own variable.
rgbImage = storedStructure.myImage;  % Or whatever the field for the image is called.
imwrite(rgbImage, 'my RGB image.PNG');

[Damian Wierzbicki]

Thank you. I get the same using this method, a white rectangle.