## Luminance image to log domain

### Elysi Cochin (view profile)

on 5 Oct 2013
Latest activity Edited by Image Analyst

on 5 Oct 2013

### Image Analyst (view profile)

Please can someone help me convert luminance image to its logarithm domain

i did like this

``` L = log(lum + 1);
figure(3); imshow(L); title('Logarithmic Image');```

and i got an output, but i wanted it as

``` magnify the luminance 10^6 times.
It is calculated as follows: L = ln(lum ・ 10^6 + 1)
ln() represents the natural logarithm.
Finally, the gray image is found by scaling L into range [0, 1]:
L = L/ max(L), where max(L) represents the maximum value of L```

so i modified the code as

``` L = log(lum * 10^6 + 1);
L = L/ max(L);
figure(3); imshow(L); title('Logarithmic Image');```

but now i dont get any output.... i just get a line in my output figure..... no error... but, please can someone help me how to code it.....

## Products

No products are associated with this question.

### Image Analyst (view profile)

on 5 Oct 2013
Edited by Image Analyst

### Image Analyst (view profile)

on 5 Oct 2013

It's a floating point image, not uint8, so you need to use [] in imshow():

```imshow(L, []);
```

and get rid of the division by max(L) - it's not needed. Anyway I don't know why you didn't get an error since max(L) would be a row vector since it's the max over columns of your scaled lum array.

#### Join the 15-year community celebration.

Play games and win prizes!

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi