32-bit images

[Beatriz Martínez Navarro]

I am trying to correct TCA with the plugin Turbo Reg.

Working with 8-bit grayscale images, when I aplly Turbo Reg the resulting
image is a 32-bit image, and the contrast is different from the original
image.

I would like to know if there is some method to create 8-bit images with
Turbo Reg (not 32-bit) and why the contrast changes when transforming an
image from 8-bit to 32-bit.

Thank you

Bea Martinez

[Wayne Rasband]

> I am trying to correct TCA with the plugin Turbo Reg.
>
> Working with 8-bit grayscale images, when I aplly Turbo Reg the
> resulting image is a 32-bit image, and the contrast is different from
> the original image.
>
> I would like to know if there is some method to create 8-bit images
> with Turbo Reg (not 32-bit) and why the contrast changes when
> transforming an image from 8-bit to 32-bit.

The contrast changes when you convert from 8 to 32 bits because 8-bit
images use a default display range of 0-255 and 32-bit images use a
default display range of minPixelValue-maxPixelValue.

As a demonstration:

1. Open the Fibroblast_Cell_Nucleus sample image.
2. Press h to get a histogram. Notice that the pixel value range is
6-120.
3. Press shift-c to open the B&C window. Notice that the display range
is 0-255.
4. Convert to 32-bits (Image>Type>32-bit). Notice that the contrast
changed.
5. Activate the B&C window. Notice that the display range is now 6-120.
6. Click "Set" and change the display range to 0-255. Notice that the
contrast is restored.

-wayne

[Beatriz Martínez Navarro]

Thank you Wayne,

It works.

Bea Martinez

>From: Wayne Rasband <[hidden email]>
>Reply-To: ImageJ Interest Group <[hidden email]>
>To: [hidden email]
>Subject: Re: 32-bit images
>Date: Thu, 6 Jul 2006 11:17:27 -0400
>
>>I am trying to correct TCA with the plugin Turbo Reg.
>>
>>Working with 8-bit grayscale images, when I aplly Turbo Reg the resulting
>>image is a 32-bit image, and the contrast is different from the original
>>image.
>>
>>I would like to know if there is some method to create 8-bit images with
>>Turbo Reg (not 32-bit) and why the contrast changes when transforming an
>>image from 8-bit to 32-bit.
>
>The contrast changes when you convert from 8 to 32 bits because 8-bit
>images use a default display range of 0-255 and 32-bit images use a default
>display range of minPixelValue-maxPixelValue.
>
>As a demonstration:
>
>1. Open the Fibroblast_Cell_Nucleus sample image.
>2. Press h to get a histogram. Notice that the pixel value range is 6-120.
>3. Press shift-c to open the B&C window. Notice that the display range is
>0-255.
>4. Convert to 32-bits (Image>Type>32-bit). Notice that the contrast
>changed.
>5. Activate the B&C window. Notice that the display range is now 6-120.
>6. Click "Set" and change the display range to 0-255. Notice that the
>contrast is restored.
>
>-wayne