"Brighten" image for viewing without changing image

[mckaybailey]

Hi all,

I'm working with linear images, which can be rather dark. Is there a way to brighten these images so that I can see them better when I am selecting areas of the image for measuring the average RGB? I basically want to apply a gamma that I can see, but that isn't actually applied to the image.

Many thanks,
Bailey

[John Oreopoulos]

Hey Bailey,

You can preview the gamma function without actually applying it to an image. First, choose your RGB image of interest, and then select Process->Math->Gamma in the menu bar to bring up the Gamma dialog box. Click the preview option box and change the gamma value. The original image will show the result on the original image. Click cancel to not apply the filter to the image and go back to the original.

Cheers,

John Oreopoulos
Research Assistant
Spectral Applied Research
Richmond Hill, Ontario
Canada
www.spectral.ca



On 2012-07-15, at 7:01 PM, mckaybailey wrote:

> Hi all,
>
> I'm working with linear images, which can be rather dark. Is there a way to
> brighten these images so that I can see them better when I am selecting
> areas of the image for measuring the average RGB? I basically want to apply
> a gamma that I can see, but that isn't actually applied to the image.
>
> Many thanks,
> Bailey
>
> --
> View this message in context: http://imagej.1557.n6.nabble.com/Brighten-image-for-viewing-without-changing-image-tp4999423.html
> Sent from the ImageJ mailing list archive at Nabble.com.
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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[mckaybailey]

Hi John,

Unfortunately, I'm not able to select areas of my image and measure them with the color histogram while previewing a gamma. Any idea how I might set a preview gamma while still being able to select and measure the original image?

Bailey

[Jim Passmore-2]

On Sun, Jul 15, 2012 at 7:22 PM, mckaybailey <[hidden email]> wrote:

> Unfortunately, I'm not able to select areas of my image and measure them
> with the color histogram while previewing a gamma. Any idea how I might set
> a preview gamma while still being able to select and measure the original
> image?
>

Bailey,
You can do Image>Duplicate, then Process>Math>Gamma (check preview, adjust
slider, then OK) as John suggested.  Make your selection on the adjusted
image, then switch to the original and then Edit>Selection>Restore
Selection.  Adjusted image can then be closed.

A bit cumbersome if you've got a lot of images, but works.

hth


*Jim Passmore*
Research Associate
Sealed Air Corporation

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[Michael Schmid]

Hi Bailey,

Two variants of this suggestion:
- Use Analyze>Tools>Synchronize Windows, with one image with nice contrast and one where you do the measurement.
- Or, even nicer, use the 'Redirect to' feature of Analyze>Set Measurements.

Michael
________________________________________________________________
On Jul 16, 2012, at 04:03, Jim Passmore wrote:

> On Sun, Jul 15, 2012 at 7:22 PM, mckaybailey <[hidden email]> wrote:
>
>> Unfortunately, I'm not able to select areas of my image and measure them
>> with the color histogram while previewing a gamma. Any idea how I might set
>> a preview gamma while still being able to select and measure the original
>> image?
>>
>
> Bailey,
> You can do Image>Duplicate, then Process>Math>Gamma (check preview, adjust
> slider, then OK) as John suggested.  Make your selection on the adjusted
> image, then switch to the original and then Edit>Selection>Restore
> Selection.  Adjusted image can then be closed.
>
> A bit cumbersome if you've got a lot of images, but works.
>
> hth
>
>
> *Jim Passmore*
> Research Associate
> Sealed Air Corporation
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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[mckaybailey]

Hi All,

Thank you all very much for the helpful responses. All of these suggestions work. However, they seem to be a bit time-consuming, and I have thousands of images to measure. The solution I decided on doesn't actually involve ImageJ at all. I simply created a display profile for my computer monitor that has a gamma adjusted to make the linear pictures look gamma corrected. Of course, this display makes the rest of my computer screen look washed out, but I simply turn off the profile when I'm not measuring.

Thanks again.

Bailey

[Jan Eglinger-3]

Hi Bailey,

On 16.07.2012 5:27 PM, mckaybailey wrote:
> Thank you all very much for the helpful responses. All of these suggestions
> work. However, they seem to be a bit time-consuming, and I have thousands of
> images to measure. The solution I decided on doesn't actually involve ImageJ
> at all. I simply created a display profile for my computer monitor that has
> a gamma adjusted to make the linear pictures look gamma corrected. Of
> course, this display makes the rest of my computer screen look washed out,
> but I simply turn off the profile when I'm not measuring.

Instead of all that hassle, you could as well use a gamma-adjusted
lookup table (LUT). I've created one for gamma 0.5 (using a simple
spreadsheet), that I've attached. You can import it using
LUT_Importer.java from
http://rsbweb.nih.gov/ij/plugins/lut-importer.html

It should also be possible to dynamically change the LUT for different
gamma values via scripting, using something like:

lut = new LUT(byte[] r, byte[] g, byte[] b)
imp.getProcessor().setLut(lut);

for the java documentation see:
http://fiji.sc/javadoc/ij/process/LUT.html
http://fiji.sc/javadoc/ij/process/ImageProcessor.html#setLut(ij.process.LUT)

Hope that helps,
Jan


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[LIM Soon Yew John (IMB)]

Hi Bailey,

I had wrote a macro that will adjust the selected LUT based on the gamma value. And I had attached my macro in this e-mail. You can copy this macro into the "plugins" folder of ImageJ and restart ImageJ. After restart, you will find this macro in the "Plugins" menu.

When you run this macro, a dialog box will pop up to ask you to select a LUT and set the gamma value. After you click "Ok", this macro will automatically adjust the selected LUT based on the gamma value.

Hope this help,
John

________________________________________
From: ImageJ Interest Group [[hidden email]] On Behalf Of Jan Eglinger [[hidden email]]
Sent: Tuesday, July 17, 2012 4:45 PM
To: [hidden email]
Subject: Re: "Brighten" image for viewing without changing image

Hi Bailey,

On 16.07.2012 5:27 PM, mckaybailey wrote:
> Thank you all very much for the helpful responses. All of these suggestions
> work. However, they seem to be a bit time-consuming, and I have thousands of
> images to measure. The solution I decided on doesn't actually involve ImageJ
> at all. I simply created a display profile for my computer monitor that has
> a gamma adjusted to make the linear pictures look gamma corrected. Of
> course, this display makes the rest of my computer screen look washed out,
> but I simply turn off the profile when I'm not measuring.

Instead of all that hassle, you could as well use a gamma-adjusted
lookup table (LUT). I've created one for gamma 0.5 (using a simple
spreadsheet), that I've attached. You can import it using
LUT_Importer.java from
http://rsbweb.nih.gov/ij/plugins/lut-importer.html

It should also be possible to dynamically change the LUT for different
gamma values via scripting, using something like:

lut = new LUT(byte[] r, byte[] g, byte[] b)
imp.getProcessor().setLut(lut);

for the java documentation see:
http://fiji.sc/javadoc/ij/process/LUT.html
http://fiji.sc/javadoc/ij/process/ImageProcessor.html#setLut(ij.process.LUT)

Hope that helps,
Jan


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[LIM Soon Yew John (IMB)]

Hi Bailey,

The ImageJ mailing server add two extra lines below to the end of my macro in the preious e-mail and this caused an error.
"
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ImageJ mailing list: http://imagej.nih.gov/ij/list.html
"
Please remove these two lines and resave the macro.

Best Regards,
John
________________________________________
From: ImageJ Interest Group [[hidden email]] On Behalf Of LIM Soon Yew John (IMB) [[hidden email]]
Sent: Tuesday, July 17, 2012 5:06 PM
To: [hidden email]
Subject: Re: "Brighten" image for viewing without changing image

Hi Bailey,

I had wrote a macro that will adjust the selected LUT based on the gamma value. And I had attached my macro in this e-mail. You can copy this macro into the "plugins" folder of ImageJ and restart ImageJ. After restart, you will find this macro in the "Plugins" menu.

When you run this macro, a dialog box will pop up to ask you to select a LUT and set the gamma value. After you click "Ok", this macro will automatically adjust the selected LUT based on the gamma value.

Hope this help,
John

________________________________________
From: ImageJ Interest Group [[hidden email]] On Behalf Of Jan Eglinger [[hidden email]]
Sent: Tuesday, July 17, 2012 4:45 PM
To: [hidden email]
Subject: Re: "Brighten" image for viewing without changing image

Hi Bailey,

On 16.07.2012 5:27 PM, mckaybailey wrote:
> Thank you all very much for the helpful responses. All of these suggestions
> work. However, they seem to be a bit time-consuming, and I have thousands of
> images to measure. The solution I decided on doesn't actually involve ImageJ
> at all. I simply created a display profile for my computer monitor that has
> a gamma adjusted to make the linear pictures look gamma corrected. Of
> course, this display makes the rest of my computer screen look washed out,
> but I simply turn off the profile when I'm not measuring.

Instead of all that hassle, you could as well use a gamma-adjusted
lookup table (LUT). I've created one for gamma 0.5 (using a simple
spreadsheet), that I've attached. You can import it using
LUT_Importer.java from
http://rsbweb.nih.gov/ij/plugins/lut-importer.html

It should also be possible to dynamically change the LUT for different
gamma values via scripting, using something like:

lut = new LUT(byte[] r, byte[] g, byte[] b)
imp.getProcessor().setLut(lut);

for the java documentation see:
http://fiji.sc/javadoc/ij/process/LUT.html
http://fiji.sc/javadoc/ij/process/ImageProcessor.html#setLut(ij.process.LUT)

Hope that helps,
Jan


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