plotting pixel values on a 256x256 image when only some pixel co-ordinates are known, and the unknowns can be 0 or NaN

I have the indices (x,y co-ordinates) and pixel values i want to visualise on a 256x256 image (i don't have all the pixel co-ordinates, so the "missing pixels" I just want displayed as 0 or Na

my data is uploaded and is 3 columns X co-ordinate, Y coordinate and pixel value in the 3rd column

sorry stupid question but how do I do this?

thanks

Answer 1

[Image Analyst]

This works:

s = load('XYpixelvalue.mat')
x = int32(s.dataXYZ(:, 1));
y = int32(s.dataXYZ(:, 2));
grayLevels = uint8(s.dataXYZ(:, 1));
grayImage = zeros(max(y), max(x), 'uint8');
for k = 1 : length(x);
  grayImage(y(k), x(k)) = grayLevels(k);
end
imshow(grayImage);
axis('on', 'image');

[cgenes]

hi this is great - but can we do it without using the uint8 functions and keep the original 1-6 pixel value - maybe using imagesc() or something, with colorbar too -so there are essentally 6 colors (and white for zeros)?

thanks very much for quick reply

[Image Analyst]

The original pixel values are in the range 1-255, NOT 1-6. Check your mat file again. You can leave them as double if you want, but you'll have to use [] in imshow() to see them and you'll have to set up a colormap if you want that to be an indexed image.

[cgenes]

Hi thanks for your help