MATLAB Central Newsreader - Black and white switch

Black and white switch

Phil Au — Fri, 29 Feb 2008 00:09:06 -0500

Hi all,

Does anyone know that a way to turn a logical image or
uint8 image, from black background to white background from
white line to black line in a simple step??

Thx a lot

Re: Black and white switch

Matthew Whitaker — Fri, 29 Feb 2008 00:44:09 -0500

"Phil Au" <philipawt@gmail.com> wrote in message <fq7if2
$nmt$1@fred.mathworks.com>...
> Hi all,
>
> Does anyone know that a way to turn a logical image or
> uint8 image, from black background to white background
from
> white line to black line in a simple step??
>
> Thx a lot

imshow(L)

imshow(~L)%where L is a logical image

imshow(u8)
imshow(intmax(class(u8))-u8) %where u8 is a uint8 image

Hope this helps
Matt

Re: Black and white switch

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) — Tue, 04 Mar 2008 21:18:52 -0500

In article <fq7kgp$j2a$1@fred.mathworks.com>,
Matthew Whitaker <mattlwhitaker@REMOVEgmail.com> wrote:
>"Phil Au" <philipawt@gmail.com> wrote in message <fq7if2
>$nmt$1@fred.mathworks.com>...

>> Does anyone know that a way to turn a logical image or
>> uint8 image, from black background to white background
>from
>> white line to black line in a simple step??

>imshow(u8)
>imshow(intmax(class(u8))-u8) %where u8 is a uint8 image

Unfortunately that last line does not generalize to int8
as might be hinted by the use of intmax(class(u8)) instead than
the hardcoding of the constant 255.

This generalizes a little better, provided T is one of the int classes.

reshape(typecast(bitxor(typecast(T(:),'uint8'),uint8(255)),class(T)),size(T))
--
"There are some ideas so wrong that only a very intelligent person
could believe in them." -- George Orwell

Re: Black and white switch

Vihang Patil — Wed, 05 Mar 2008 05:22:01 -0500