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yvdh

Chart White Balance and exposure adjustment

9 posts in this topic

Hallo,

this plugin can be used to adjust the white balance of a picture based on the white and black patch a standard color chart in the scene. It will use their known sRGB values to bring the image closer to sRGB specs, but it is NOT a full color calibration as described on my website at C4Real. Useful in medical photography, forensics, etc. ...

version 1.0

-----------

Supported charts: MacBeth Color Checker Chart A4 and small, QP Card 201.

Instructions:

- Install plugin

- Set primary color to that of the white patch, and secondary to the black patch (can be omitted)

- Adjustments -> Color -> ChartWhiteBalance

- Select other chart if required,turn off use of black if required.

- Close

Any constructive comments are warmly welcomed

Yves

Version 1.1 (12 sept 2010)

--------------------------

Changes

- Not using codelab anymore, full project in VS gives me more flexibility, especially when debugging. Btw CodeLab is still a great tool to get started!

- Added another type of chart we are using (medicol).

- Added some checks which would lead to division by zero errors

- Added a little info on the tool dialog (users were confused without help).

- Appears in the Effects / Photo menu now.

Version 1.2 (13 sept 2010)

--------------------------

Changes

- Added a virtual absolute white and black chart: choosing this means image black is mapped to (0,0,0) and white to (255,255,255). This is useful

for general white balancing

- Added automatic detection of image white and black using a 5 x 5 window

Version 1.2.1 (21 sept. 2010): Bugfix

-------------------------------------

Changes

- Removed a bug whereby the LUT had erronuous values for R*G*B* index = 1. This was visible as usually brightly coloured single pixels in the image.

Paint.NET.ChartWhiteBalance.zip

ChartWhiteBalance1.2.zip

ChartWhiteBalance1.1.zip

ChartWhiteBalance1.2.1.zip

Edited by yvdh
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So the bottom row is the calibration by your plugin, and the middle row is calibration by some other program?

Looks interesting. I have no immediate need for this, but will still definitely play around with it. Do you have to buy that color chart or can one simply print it out?

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Both rows are results of calibration with software I have written during and after my Phd. Unfortunately, the more advanced and better version is not entirely mine to give away.

The chart can be bought online and in specialized stores. The QP chart is about 16 Euros for 2, the MacBeth Color Checker chart is much more expensive at 40-50 Euros for the small and maybe 60-70 Euros for the A4 sized one. This is a much better chart though ...

Yves

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What are the differences between this and Ed Harvey's color filter?

Excuse my silliness.

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Hallo,

as far is I can tell Ed's filter is a manual adjustment of the color components scaling (correct me if wrong). My filter is a 3 step lookup-table allowing different scaling for each region (I am working on a 7 step LUT). Also I am using charts with KNOWN colorimetric properties, so althoug the marking of the chart is manual, the actual white balance is NOT. It is fixed to obtain a rendition of the scene as if under a D65 light source and using the sRGB color space.

Yves

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Hallo,

just updating the version of my plugin slightly:

Changes

- Not using codelab anymore, full project in VS gives me more flexibility, especially when debugging. Btw CodeLab is still a great tool to get started!

- Added another type of chart we are using.

- Added some checks which would lead to division by zero errors

- Added a little info on the tool dialog (users were confused without help).

- Appears in the Effects / Photo menu now.

Instructions:

- Install plugin

- Set primary color to that of the white patch, and secondary to the black patch (can be omitted)

- Effects -> Photo -> ChartWhiteBalance

- Select other chart if required,turn off use of black if required.

- Close

I am working on a version which will allow interactive marking of the black and white patch. This will allow usage of ALL the gray patches located inbetween. This should result in a much better LUT for the image correction (I have this working already in ImageJ, which is an open source imaging program for microscopy).

Any questions and constructive comments are warmly welcomed.

Yves

ChartWhiteBalance.zip

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Please update the link in the first post so users can find the latest release more easily boltbait.wink.png

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Please update the link in the first post so users can find the latest release more easily boltbait.wink.png

Good point, done!

Also added an even newer version.

Yves

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