im2uint8 only generates 0 or 255

I am trying to present an image of class double using imshow.

suppose this is the image:

a = [78.4630409671845,90,0;
    78.4630409671845,36.8698976458440,62.5135737496187;
    0,0,0]

now when I try to convert it to uint8 in order to show it, this is what I get:

b = im2uint8(a) = [255,255,0;
                   255,255,255;
                   0,0,0]

but I expect something like this:

b = [78,90,0;
     78,37,63;
     0,0,0]

so the imshow command shows a weird black an white image:

imshow(a);
imshow(a,[]);
imshow(b);
imshow(b,[]);

How can I properly present a double image?

Answer 1

[Jan]

im2uint8 expects the input to be an RGB image, which is a 3D array with values from 0 to 1. So normalize your data at first by dividing by 255:

a = [78.4630409671845,90,0;
    78.4630409671845,36.8698976458440,62.5135737496187;
    0,0,0]
im2uint8(a / 255)

[Steven Lord]

Or even more simply, just call uint8 on it.

a = [78.4630409671845,90,0;
    78.4630409671845,36.8698976458440,62.5135737496187;
    0,0,0];
aJan = im2uint8(a / 255)

aJan = 3×3

78 90 0 78 37 63 0 0 0

aSteve = uint8(a)

aSteve = 3×3

78 90 0 78 37 63 0 0 0

[Hadi Ghahremannezhad]

@Steven Lord thanks. this worked great.