how to convert matrix to graysclae image?
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jiji hr
el 23 de Mayo de 2016
Comentada: jiji hr
el 25 de Mayo de 2016
Hi, I have a matrix that i have extacted using spin images descriptor, it is of size 15x15 :
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/164883/image.png)
I want to display it in gray scale but it doesn't work. I tried to use imshow() like this :
imshow(uint8(spinImages(1,1).spinIm),'DisplayRange',[0 255])
imshow(255-uint8(spinImages(1,1).spinIm),'DisplayRange',[0 255])
and also i used imagesc :
imagesc(255-uint8(spinImages(1,1).spinIm), [0 255])
imagesc(1-uint8(spinImages(1,1).spinIm), [0 255])
imagesc(uint8(spinImages(1,1).spinIm), [0 255])
but worthless. pleaz could you help me.
6 comentarios
Adam
el 25 de Mayo de 2016
Editada: Adam
el 25 de Mayo de 2016
imagesc( spinImages(1,1).spinIm );
colormap( flipud(gray) );
will give you a white background and high values as black if that is what you want visually.
Obviously you can also inverse the data itself - it depends if you want the data inverted for other purposes than visualisation too.
Respuesta aceptada
Guillaume
el 23 de Mayo de 2016
Editada: Guillaume
el 23 de Mayo de 2016
" but it doesn't work". In what way?
What you've showed will display the image, possibly not the way you want, but it will display it.
I'll note that the intensity range in your screenshot is up to 3906. Because of the call to uint8, any intensity above 255 will be set to 255. I'm not sure that's what you want.
There's certainly no reason to convert to uint8 if you're going to restrict the display range to [0 255] anyway.
Possibly, you meant:
imshow(spinImages(1,1).spinIm, [])
3 comentarios
Guillaume
el 25 de Mayo de 2016
If you want to inverse the image:
imshow( max(spinImages(1, 1).spinIm(:)) - spinImages(1,1).spinIm, [])
would be better than the completely unnecessary conversion to uint8.
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